ACSM-PA Strategies for Wt Loss

  ACSM POSITION STAND

SPECIAL COMMUNICATIONS

Appropriate Physical Activity Intervention Strategies for Weight Loss and Prevention of Weight Regain for Adults POSITION STAND This pronounceme pronouncement nt was written for the American American College College of  Sports Medicine by Joseph E. Donnelly, Ed.D. (Chair); Steven N. Blair, PED; John M. Jakicic, Ph.D.; Melinda M. Manore, Ph.D., R.D.; Janet W. Rankin, Ph.D.; and Bryan K. Smith, Ph.D.

This This docu docume ment nt is an upda update te of the the 2001 2001 Amer Americ ican an College of Sports Medicine (ACSM) Position Stand titled ‘‘Appropriate Intervention Strategies for Weight Loss and Preve Preventi ntion on of Weigh Weightt Rega Regain in for for Adult Adults’ s’’’ (68). (68). This This Position Stand provided a variety of recommendations such as the the iden identif tific icat atio ion n of adult adultss for for whom whom weigh weightt loss loss is recommended, the magnitude of weight loss recommended, dietary recommendations, the use of resistance exercise, the use of pharmacologic pharmacological al agents, behavioral behavioral strategies, strategies, and other topics. The purpose of the current update was to focus on new informati information on that that has been publish published ed after after 1999, 1999, which may indicate that increased levels of physical activity (PA) may be necessary for prevention of weight gain, for  weight loss, and prevention of weight regain compared to those tho se reco recomm mmen ende ded d in the the 200 2001 1 Posi Positio tion n Stan Stand. d. In  particular, this update is in response to published information tion rega regardi rding ng the the amoun amountt of PA need needed ed for for weig weight  ht  management management found in the National Weight Control Registry Registry (155) and by the Institute of Medicine (67). This update was undertaken for persons older than 18 yr  who were enrolled in PA trials designed for prevention of  weight gain (i.e., weight stability), for weight loss, or prevention of weight regain. Investigations that include older  adults (i.e., older than 65 yr) are not abundant. Some concerns exist for the need for weight loss in older adults and for  loss of fat-free mass and potential bone loss. This review considers the existing literature as it applies to the general  population. However, it is likely that individuals vary in their  respons responsee to PA for preven prevention tion of weight weight gain, gain, for for weight weight loss, loss, and for weight weight mainte maintenanc nance. e. Trials Trials with with indi individ vidual ualss with with comorbi comorbid d conditi conditions ons that that acutel acutely y affect affect weight weight and trials trials using using pharma pharmacot cother herapy apy were were not include included d (i.e., (i.e., acquire acquired d immunodeficie immunodeficiency ncy syndrome, syndrome, type 1 diabetes). diabetes). Trials using individuals individuals with medication medication and comorbid diseases, such as hyperte hypertensi nsion, on, cardiov cardiovasc ascula ularr diseas diseasee (CVD), (CVD), and type 2

 ABSTRACT Overweight Overweight and obesity affects more than 66% of the adult population and is associated with a variety of chronic diseases. Weight reduction reduces health risks associated with chronic diseases and is therefore encouraged by major health agencies. Guidelines of the National Heart, Lung, and Blood Instit Institute ute (NHLBI (NHLBI)) encour encourage age a 10% reduct reduction ion in weight weight,, althou although gh considerable literature indicates reduction in health risk with 3% to 5% reductio reduction n in weight weight.. Physic Physical al activit activity y (PA) (PA) is recommen recommended ded as a  compon component ent of weight weight manage managemen mentt for preven preventio tion n of weight weight gain, gain, for  weight loss, and for prevention prevention of weight regain after weight loss. In 2001, the American College of Sports Medicine (ACSM) published a Position Stand Stand that that recomm recommend ended ed a minimu minimum m of 150 minIwk j1 of moderatemoderateintensity PA for overweight and obese adults to improve health; however, 200–300 200–300 minIwk j1 was recommended recommended for long-term weight loss. More recent evidence has supported this recommendation and has indicated more PA may be necessary to prevent weight regain after weight loss. To this end, we have reexamined the evidence from 1999 to determine whether  there is a level at which PA is effective for prevention of weight gain, for  weight loss, and prevention of weight regain. Evidence supports moderateintensity PA between 150 and 250 minIwk j1 to be effective to prevent  weight gain. Moderate-intensity PA between 150 and 250 min Iwk j1 will  provide only modest weight loss. Greater amounts of PA (9250 minIwk j1) have been associated associated with clinically clinically significant significant weight weight loss. ModerateModerateintensity PA between 150 and 250 minIwk j1 will improve weight loss in studies that use moderate diet restriction but not severe diet restriction. Cross-sectio Cross-sectional nal and prospective prospective studies indicate that after weight loss, weight maintenance is improved with PA 9250 minIwk j1. However, no evidence from well-designed randomized controlled trials exists to judge the effectiveness of PA for prevention of weight regain after weight loss. Resistance Resistance training does not enhance enhance weight loss but may increase fat-free mass and increase loss of fat mass and is associated with reductions in health risk. Existing evidence indicates that endurance PA or resistance training training without without weight weight loss improves health risk. There is inadequate inadequate eviden evidence ce to determi determine ne whethe whetherr PA prevent preventss or attenu attenuate atess detrim detriment ental al changes in chronic disease risk during weight gain.

0195-9131/09/4102-0459/0 MEDICINE & SCIENCE IN SPORTS & EXERCISEÒ Copyright  Ó 2009 by the American College of Sports Medicine DOI: 10.1249/MSS.0b013e3181949333

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diabetes, were included because these individuals are very   prevale prevalent nt in the United United States States (US) (US) and ind individ ividuals uals with these these condi conditio tions ns are are freq freque uentl ntly y in need need of weigh weightt loss loss.. Throughout this paper light-intensity activity is defined as 1.1 to 2.9 METS, moderate-intensity activity is 3.0 to 5.9 METS, and vigorous activity is Q 6 METS (U.S. Department  of Health and Human Services Website [Internet]. Washington, DC: 2008 Physical Activity Guidelines for Americans; cans; [cited [cited 200 2008 8 Nov 17]. 17]. Availa Available ble from from http:/ http://  /  www.health. www.health.gov/PAG gov/PAGuidelin uidelines.) es.) The Evidence Evidence Categories Categories of the National Heart, Lung, and Blood Institute (NHLBI) were used to evaluate the strength of the literature and to support recommendations (Table 1).

RATIONALE FOR WEIGHT MANAGEMENT

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Overweight and obesity are defined by a body mass index (BMI) of 25 to 29.9 kgImj2 and and 30 kgImj2 or greater, greater, respectively. Together, overweight and obesity are exhibited   by approximately 66.3% of adults in the US (107). Both overweight and obesity are characterized by the accumulation of excessive levels of body fat and contribute to heart  disease, hypertension, diabetes, and some cancers as well as   psychosocial and economic difficulties (55,97,99,147). The cost of treatmen treatmentt of weight weight reductio reduction n is now estimate estimated d to exceed exceed $11 $117 7 billio billion n annual annually ly (135). (135). Reduc Reductio tion n in the  prevalence of obesity was among the major aims of Healthy People 2000 (147), although it is now apparent that this goal was was not achie achieved ved (148). (148). Reduc Reductio tion n in obesi obesity ty rema remains ins a  major aim of Healthy People 2010 (146) and of other major  health health campaig campaigns ns (i.e., (i.e., Steps to a Healthie HealthierUS rUS Initiati Initiative, ve, http://www.heal http://www.healthierus. thierus.gov/steps gov/steps/; /; Make Your Calories Calories Count, http://www.cfsa http://www.cfsan.fda.gov/ n.fda.gov/~dms/hwm ~dms/hwm-qa.html -qa.html;; We Can! http://www.nhlbi.nih. http://www.nhlbi.nih.gov/healt gov/health/public/hea h/public/heart/obesity rt/obesity/  /  wecan/). Management of overweight and obesity is considered an important public health initiative because numerous studie studiess have have sho shown wn the benefi beneficia ciall effec effects ts of dim dimini inishe shed d weight and body fat in overweight and obese individuals. These beneficial effects include an improvement in CVD risk  factor factorss such such as decrea decreased sed blood blood pressu pressure re (85,10 (85,102,1 2,137), 37), decreased decreased LDL-C (24,85,151), increased HDL-C (24,151), decrea decreased sed trigly triglycer ceride idess (TG) (TG) (24,43 (24,43,15 ,151), 1), and imp improv roved ed

glucose tolerance (30,45). Weight loss has also been associated with a decrease in inflammatory markers, such as Creactive protein (60,81,139), which have also been associated with with the the deve develop lopme ment nt of CVD CVD (118, (118,11 119) 9).. The The NHLB NHLBII Guidel Guideline iness (101) (101) recom recomme mend nd a min minim imum um weigh weightt loss loss of  10%. However, there are also numerous studies that show  beneficial improvements in CVD risk factors when weight  loss is less than 10% (16,38,56,80,114,150). In fact, beneficial improvements in chronic disease risk factors have been reported with as little as 2–3% of weight loss (30,45,85,141).

POTENTIAL NEED FOR GREATER  AMOUNTS OF PA  PA is reco recomm mmen ende ded d as an impor importa tant nt part part of weig weight  ht  manage managemen mentt by virtual virtually ly all public public health health agenci agencies es and scientific organizations including NHLBI (41), Centers for  Dise Diseas asee Cont Contro roll (CDC) (CDC) (57) (57),, ACSM ACSM (57), (57), and and vari various ous medical medical societies societies (American (American Heart Association, Association, American American Medical Association, American Academy of Family Physicians) (92). Although there are existing recommendations for the amount of PA useful for weight management, recent  studies have suggested greater amounts may be needed for  most individuals. For example, individuals in the National Weight Control Registry who have maintained weight loss have shown levels levels of energy energy expend expenditur ituree equiva equivalen lentt to j1 walking È28 milesIwk  (78). Schoeller et al. (126) used doubly doubly labele labeled d water water to study study women women who recently recently lost  lost  23 T 9 kg weight to estimate the energy expenditure needed to prevent weight regain. Retrospective analyses of the data  were performed to determine the level of PA that provided maximum differentiation between gainers and maintainers. On the basis of these analyses, it was determined that sedentary individuals would need to perform È80 minIdj1 of  modera moderatete-int intensi ensity ty PA or 35 minIdj1 of vigorous PA to   preven preventt weight weight regain regain.. These These studie studiess contri contribute buted d to the 2001 recommendation by ACSM of 200–300 minIwk j1 of  moderate-intensity PA for long-term weight loss, and other   published recommendations (i.e., Institute of Medicine [67]) suggest that greater amounts of PA may be necessary for   prevention of weight regain after weight loss. In response, we have examined the literature from 1999 to present to

TABLE 1. Level of evidence for evidence statements. Evidence Category

Evidence Statement

PA to prevent weight gain. PA of 150 to 250 minIwkj1 with an energy equivalent of 1200 to 2000 kcalIwkj1 will will preven preventt weight weight gain gain greate greaterr than than 3% in most most adults adults.. PA for weight loss. PA G 150 minIwkj1 promotes minimal weight loss, PA 9 150 minIwkj1 results in modest weight loss of È2–3 kg, PA 9 225–420 minIwkj1 results in 5- to 7.5-kg weight loss, and a dose–response exists. PA for weight maintenance after weight loss. Some studies support the value of È200- to 300-minIwkj1 PA during weight maintenance to reduce weight regain after weight loss, and it seems that ‘‘more is better.’’ However, there are no correctly designed, adequately powered, energy balance studies to provide evidence for the amount of PA to prevent weight regain after weight loss. Lifestyle PA is an ambiguous term and must be carefully defined to evaluate the literature. Given this limitation, it seems lifestyle PA may be useful to counter the small energy imbalance responsible for obesity in most adults. PA and diet restriction. PA will increase weight loss if diet restriction is modest but not if diet restriction is severe (i,e., GkcalIwkj1 needed to meet RMR). Resistance training (RT) for weight loss. Research evidence does not support RT as effective for weight loss with or without diet restriction. There is limited evidence that RT promotes gain or maintenance of lean mass and loss of body fat during energy restriction and there is some evidence RT improves chronic disease risk factors (i.e., HDL-C, LDL-C, insulin, blood pressure).

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determ determine ine whethe whetherr there there is suffic sufficien ientt eviden evidence ce to recomrecommend increased levels of PA for prevention of weight gain, weight loss, and prevention of weight regain.

WEIGHT MAINTENANCE AND CLINICALLY  SIGNIFICANT SIGNIFICANT WEIGHT LOSS The clinical significance of weight maintenance maintenance and weight  loss loss is often often questi questione oned d in studi studies es that that provid providee margi marginal nal results. To provide context to a discussion of PA for weight  maintenance, maintenance, weight loss, or prevention of weight regain after  weight loss, St Jeor et al. (133) and Sherwood et al. (129)   both operationally defined weight maintenance as a change of  e5 lb (2.3 kg). Stevens et al. (136) recently recommended a definition of weight maintenance as G3% change in body weight weight with 95% change change in bod body y weight weight consi consider dered ed as clinically significant. significant. There There are also also problem problemss with with setting setting operati operating ng definidefinitions. tions. Benef Benefits its associ associate ated d with with weigh weightt maint maintena enance nce or  weig weight ht chan change gess like likely ly exis existt on a cont continu inuum um and and do not  operate operate und under er a thresh threshold. old. The definit definitions ions above are the  product of observational studies and review of the literature. ture. Random Randomize ized d control controlled led trials trials that that were were designe designed d to  provide evidence to answer the question of clinical significance have not been conducted. Indeed, such trials may be unrea unrealis listi ticc and and may may not yiel yield d a clea clearr defi definit nition ion.. Thus, Thus,   judgment of clinical significance remains a topic for continued research and under the interpretation of the reader. Eviden Evidence ce Statem Statemen ent: t: PA Will Will Preven Preventt Weig Weight ht Primary preventi prevention on of  Gain. Gain. Eviden Evidence ce Catego Category ry A. Primary obesi obesity ty star starts ts with with maint mainten enan ance ce of curr curren entt weigh weight, t, not  weight reduction. The risk for weight gain may vary across time, and the need for PA to prevent weight gain, therefore, may also vary. However, studies that test this promise are lacking. lacking. A considerable considerable amount of cross-secti cross-sectional onal evidence indicat indi cates es an inv invers ersee relatio relationsh nship ip betwee between n body weight weight or  BMI and PA (5,94). In addition, a small dose–response relationship is shown for the decrease in body weight or BMI as PA levels increase. For example, Kavouras et al. (76) reported a significantly lower BMI (25.9 kgImj2) for individuals participating in PA equivalent to at least 30 minIdj1 for 5 dIwk j1 when when compar compared ed to less less active active indi individ viduals uals (26.7 kgImj2). However, Berk et al. (7) found that individuals who initially initially reported reported G60 minIwk j1 of PA and increased to 134 minIwk j1 of PA had a change in BMI of  0.4 kgImj2 across a 16-yr follow-up period, but this was not signif significa icantly ntly different different from from the 0.9 kgImj2 increase observed observed for ind individ ividual ualss who remaine remained d sedenta sedentary ry at bot both h j1 assessment periods (G60 minIwk  ). These data suggest that  j1 of PA will result in a nonsignificant change G150 minIwk  of weigh weightt gain gain comp compare ared d to ind indivi ividua duals ls who rema remain in sedentary. However, individuals who were classified as active at both assessment periods and were participating in 261 minIwk j1 of PA resulted in a significantly lower change in BMI compared to individuals who were initially active ( 960 minIwk j1) at baseline but became less active at follow-up

WEIGHT LOSS AND PREVENTION OF WEIGHT REGAIN

(G60 min minIwk j1). Thes Thesee two two stud studie iess supp suppor ortt the the need need to maintain a physically activity lifestyle and the need for  9150 minIwk j1 of PA to manage body weight in the long term. Additio Additional nal eviden evidence ce for the effect effective ivenes nesss of greate greater  r  amounts of PA is provided by McTiernan et al. (95). In their  study, prevention of weight gain was investigated in a 12month randomized, controlled trial that targeted 300 min of  moderately vigorous PA per wk. Women lost 1.4 T 1.8 kg compared to an increase of 0.7 T 0.9 kg in controls and men lost 1.8 T 1.9 kg compared to an increase of 0.1 T 0.1 kg in contr controls ols.. A non nonsig signif nifica icant nt dos dosee effec effectt was was sho shown wn for  j1 minutes of PA for women with 9250 minIwk  associated with greater weight loss compared to G250 minIwk j1. For  men, men, a signif significa icant nt dos dosee effec effectt was was found found for tho those se who j1 reported 9250 minIwk  compare compared d to those those who reported reported j1 G250 minIwk  . Thus, greater amounts of PA resulted in greater amounts of weight loss. Taken together, the above studies studies suggest that there there is sufficie sufficient nt evidence evidence that moderat eratel ely y vigo vigoro rous us PA of 150 150 to 250 250 min minIwk j1 with with an j1 energy energy equivale equivalent nt of  È1200 1200 to 2000 2000 kcal kcalIwk  (È12 to 20 milesIwk j1) is sufficient to prevent a weight gain greater  than 3% in most adults. Evidence Evidence Statement Statement:: PA Will Promote Promote Clinicall Clinically  y  Significa Significant nt Weight Weight Loss. Loss. Evidence Evidence Category Category B. A negative negative energy balance balance genera generated ted by PA will will result result in weight loss, and the larger the negative energy balance, the greater the weight loss. Extreme amounts of PA found with militar mil itary y traini training ng (104) (104) or mounta mountain in climbi climbing ng (116) (116) may result in substantial weight loss; however, it is difficult for  most individuals to achieve and sustain these high levels of  PA. Few studies studies with sedenta sedentary ry overwe overweight ight or obese obese individuals using PA as the only intervention result in Q3% decreases decreases of baseline baseline weight. weight. Therefore, Therefore, most individuals individuals who require require sub substa stanti ntial al weight weight loss loss may may need need additio additional nal interventions (i.e., energy restriction) to meet their weight  loss needs. Several Several studies studies that targeted targeted G150 150 min minIwk j1 of PA resulte resulted d in no signifi significan cantt change change in bod body y weight weight (10,14, (10,14, 27,98). Donnelly et al. (33), targeted 90 min of continuous modera moderatete-int intensi ensity ty PA (30 min min,, 3 dIwk j1) comp compar ared ed to 150 min of modera moderatete-int intensi ensity ty interm intermitt ittent ent PA (30 min min,, j1 5 dIwk  ) in women for 18 months. The continuous group lost significantly greater weight than the intermittent group (1.7 (1.7 vs 0.8 kg), yet yet neith neither er group group lost  lost  Q3% of baselin baselinee weight. Garrow Garrow et al. (53) and Wing (154) (154) have have review reviewed ed the literatu literature re for the effect effectss of PA for weight weight loss loss and concluded that weight loss is typically 2 to 3 kg; however, the level level of PA was not well well descri described. bed. Interesti Interestingly ngly,, wellwellcontrolled controlled laboratory studies generally find greater greater levels of  weight loss in response to PA. This may reflect a greater  amount of PA that is targeted in laboratory studies com pared to outpatient studies and verification that participants achieved the targeted amount. For example, Ross et al. (121) showed that men and women who experienced a 500- to 700-kcalIdj1 deficit for 12 wk had weight loss of 7.5 kg

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(8%) and 5.9 kg (6.5%), respectively. Donnelly et al. (32), used a randomized, controlled trial of 16 months duration that that provide provided d 225 min of modera moderatete-inte intensit nsity y PA with with a  targeted energy equivalent of  È400 kcalIdj1, 5 dIwk j1, and verified all sessions of PA in a laboratory. The difference in weight between experimental and controls at 16 months was j4.8 kg for men and j5.2 kg for women. However, these differences were achieved differently. Men who received PA lost weight compared to controls who maintained weight. Women who received PA maintained weight compared to controls who gained weight. These findings may suggest a    potent potential ial gender gender differe difference nce in respons responsee to PA. Howeve However, r, other investigations (134) have not found differences, and further further inv invest estiga igation tion for gender gender differ differenc ences es seems seems warwarranted. It is likely that any increase in PA has the potential for  weight loss; however, it seems that PA G150 minIwk j1 resultss in minimal sult minimal weight loss compare compared d to controls controls,, PA 9 j1 150 minIwk  results in modest weight loss of  È2–3 kg, and PA between 225 and 420 minIwk j1 results in 5- to 7.5-kg weigh weightt loss. loss. Thus, Thus, a dos dosee effe effect ct is appar apparent ent for PA and and weight loss, and higher doses are capable of providing 3% or greater weight loss from initial weight. Eviden Evidence ce Statem Statement ent:: PA Will Will Preven Preventt Weight Weight Regain Regain after Weight Loss. Evidence Evidence Category Category B. It is gene genera rally lly acce accept pted ed that that mo most st indiv individu idual alss can can lose lose weight but cannot maintain weight loss. PA is universally   promot promoted ed as a necess necessity ity for weight weight mainte maintenan nance ce (67,68 (67,68,, 101). 101 ). Inde Indeed ed,, PA is ofte often n cite cited d as the the best best pred predic icto torr of  weight maintenance after weight loss (78,138). A systematic review of PA to prevent weight regain after weight loss was completed by Fogelholm and Kukkonen-Harjula (47). The majorit majority y of studies studies were were observat observation ional al studie studiess and studies of individuals who were randomized at baseline to exercise exercise or no exercise, or to different different levels of PA. Followup varied varied from severa severall months months to severa severall years years and the results indicated that individuals who engaged in exercise experienced less regain than those individuals who did not, and those individuals who engaged in greater amounts of  PA experienced less regain than those with more moderate levels of PA. Only three studies used a design in which individuals were randomized to PA after weight loss (48,87,112), and the results showed that PA had an indifferent, negative, or positive effect on prevention of weight regain. Failure to randomize to PA levels after weight loss is a serious design flaw and diminishes the evidence available for evaluation. Despite Despite the accepte accepted d concep conceptt that that PA is necess necessary ary for  succe successf ssful ul weigh weightt maint maintena enance nce after after weigh weightt loss, loss, the amount amount that that is needed needed remains remains uncert uncertain ain and may may vary vary among among ind individ ividual ualss (70). (70). The CDC/ACS CDC/ACSM M recomm recommend endaations tions for PA spec specifi ified ed the the accu accumul mulat ation ion of 30 min min of  modera moderatete-int intensi ensity ty PA for most most days days of the week (111). (111). These guidelines were provided for health promotion and disease prevention; however, they were widely interpreted to be useful useful for weight managemen management. t. Minimum Minimum levels of  j1 j1 150 150 min minIwk  (30 (30 min minId , 5 dIwk j1) of mo moder derate ate--

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intens intensity ity PA were were also also reco recomm mmen ended ded by the ACSM ACSM Position Stand in ‘‘Appropriate Intervention Strategies for  Weight Loss and Prevention of Weight Regain for Adults’’ for health health benefit benefits; s; howeve however, r, 200–300 200–300 minIwk j1 was recommended for long-term weight loss (68). Jakicic et al. (69, (69,71 71)) and and Ande Anders rsen en et al. al. (2) (2) prov provid idee data data from from randomi randomized zed trials trials that that ind indica icate te ind individ ividuals uals who perform perform greater amounts of PA maintain greater amounts of weight  loss at follow-up of 18, 12, and 12 months, respectively. In   partic particula ular, r, Jakici Jakicicc et al. (69,71) (69,71) sho show w very very little little weight  weight  regain regain in ind individ ividuals uals who perform performed ed 9200 minIwk j1 of  modera moderatete-int intensi ensity ty PA. Recent Recently, ly, Jakici Jakicicc et al. (70) have have reporte reported d that that indi individu viduals als who achieve achieved d a weight weight loss loss of  910% of initial body weight at 24 months were participating in 275 minIwk j1 (approximately 1500 kcalIwk j1) of  PA activity above baseline levels. Likewise, Ewbank et al. (40) found similar results 2 yr after weight loss by a very low energy diet. Retrospectively grouping participants by levels levels of selfself-rep report orted ed PA, ind indivi ividua duals ls who report reported ed j1 greater levels of PA (walking È16 milesIwk  ) had significantly less weight regain than individuals reporting less PA per week (4.8–9.1 miles Iwk j1). However, it is important to note that individuals in all three studies mentioned were grouped into PA categories retrospectively and were not randomly assigned to these PA groups after weight loss. Thus, Thus, the amount of PA was self-sel self-select ected ed and therefo therefore re does does not provi provide de clea clearr evide evidenc ncee for the amou amount nt of PA needed to prevent weight regain. To explore the effects of levels of PA greater than those normally normally recommended recommended in weight weight management management programs, Jeffery et al. (74) targeted 1000 and 2500 kcal Iwk j1 for  18 months months in two groups of partic participan ipants, ts, and these these levels of PA were randomly assigned at baseline. The actual report reported ed energy energy expend expenditu iture re for kiloca kilocalor lories ies per week  week  at 18 months was 1629 T 1483 and 2317 T 1854 for the 1000- and 2500-kcal 2500-kcalIwk j1 groups, respectively. There were no differences for weight loss between groups at 6 months (weight loss), but there were significant differences at 12 and 18 months (weight maintenance) of follow-up with the 2500-kcalIwk j1 group showing significantly greater weight  losses (6.7 T 8.1 vs 4.1 T 7.3 kg). This study indicates that  greater levels of PA provided significantly lower levels of  weight weight regain regain.. Howeve However, r, the results results must must be interpr interpreted eted with caution because there was great variation in the percentag centagee of ind individ ividuals uals meetin meeting g the target targeted ed energy energy ex penditure, and the behavioral interventions were not equal. In summa summary, ry, most most of the availa available ble liter literatu ature re ind indica icates tes that ‘‘more is better’’ regarding the amount of PA needed to  prevent  prevent weight weight regain regain after after weight loss. loss. However, However, as indi indicate cated d above, there are some major flaws in the literature relative to the appropriate research design needed to directly address this questio question. n. Specifi Specifical cally, ly, there there are no adequat adequately ely powered powered studies of sufficient duration with randomization to different  levels of PA after weight loss. In addition, the literature is absent of randomized, controlled studies that used state-ofthe-art the-art energy energy balance balance technique techniques. s. Given Given these these limitati limitations, ons,

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weight maintenance (weight fluctuation G3%) 3%) is likel likely y to be associated associated with È60 min walking per day (È4 milesIdj1) at  a moderate intensity (40,71,126,138).

OVERVIEW OF LIFESTYLE PA  Interventions Interventions for weight loss frequently frequently implement behavioral programs that include strategies to integrate PA into the individuals’ individuals’ lifestyle. lifestyle. Examples Examples include supervised exercise, exercise, nonsupervised nonsupervised exercise, exercise, occupational occupational activity, activity, work around around the home, home, persona personall care, care, commuti commuting, ng, and leisure time activities. It is critically important to understand the difference between lifestyle intervention approaches to increasing PA and lifestyle forms of PA. The lack of clear  differences between the two has lead to confusion regarding what the term ‘‘lifestyle PA’’ really means. Part of the confusion comes from the lack of differentiation between a behavioral approach to modifying PA and specific forms of PA classified as lifestyle in nature. The following segments are offered to provide clarity for the pur pose of this review. Lifestyle Lifestyle Approach Approaches es to increasing increasing PA. Lifestyle approac approaches hes to increa increasin sing g PA refers refers to interve interventio ntions ns that  that  incorpo incorporat ratee behavi behaviora orall theorie theoriess and constr construct uctss to assist  assist  and facilitate increasing PA within one’s lifestyle. Exam ples may include, but are not limited to, inclusion of problem solvin solving, g, goal-s goal-sett etting ing,, self-m self-moni onitor toring ing,, and relaps relapsee  prevention  prevention strategies based on theories, theories, such as Social Cognitive Theory, Transtheoretical Model, Theory of Planned Behavior, and Health Belief Model. This intervention ap proach can be used to improve participation in all forms of  PA that include structured exercise, leisure time PA, occu pational PA, household PA, and PA used for commuting. Lifestyle forms of PA. Clearly defining lifestyle forms of PA is somewhat more challenging. For the purpose of  this review, review, we define define lifesty lifestyle le PA as any nonstruc nonstructure tured d form of PA performed that is not intended to constitute a  structured period of exercise. For example, walking done for commuting would be considered lifestyle PA. Walking in a structured period of exercise would not be considered lifestyle PA. Nonexercise activity thermogenesis. Levine et al. (89,90) have developed the concept of nonexercise activity thermogenesis (NEAT), which they define as all energy ex  penditure that is not from sleeping, eating, or planned exerci ercise se progr program ams. s. This This defi defini nitio tion n does does not not use use the the term term ‘‘lifestyle’’ and may therefore diminish the confusion between a lifestyle PA approach and forms of lifestyle PA. Regardless of definition, it is apparent that separating PA integrated into the lifestyle in behavioral programs from PA not associate ciated d with with planne planned d PA is curre currentl ntly y confus confusing ing and proble problema matic tic in terms of definition and measurement. Lifestyle le PA energy energy Measureme Measurement nt of lifestyle lifestyle PA. Lifesty expendit expenditure ure (PAEE) (PAEE) has been been measur measured ed in observa observatio tional nal studies studies and random randomize ized d trials trials by variou variouss methods methods.. Many Many studies have used self-report PA questionnaires to estimate

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total PA, and more recently, an objective measurement of  PA has been achieved by use of pedometers, accelerometers, inclinometers, inclinometers, or doubly labeled water assessments assessments (6,89,90,93). Although self-report of purposeful PA or exercise is sometimes crude and imprecise, it is even more difficult for individuals to provide an accurate self-report of  lifestyle PA. Most adults can remember if they went for a  run or to aerobics class and can also accurately report some types of lifestyle activity such as walking to the bus stop or to work. However, it is difficult to accurately quantify overall lifestyle activity because it constitutes hours per day and much of it is not memorable. An example of this was reported by Manini et al. (93) in a study of PAEE and mortality in a group of older adults (93). They assessed PAEE  by doubly labeled water and also administered several PA question questionnai naires res.. They They develo developed ped 21 separa separate te estima estimates tes of  time spent in PA or energy expended in PA from the questionnaire data. Only 8 of the 21 measures were significantly different across thirds of PAEE (low, G521 kcalIdj1; middle, 521–770 kcalIdj1; high, 9779 kcalIdj1), which indicate the difficulty of measuring lifestyle PA by self-report. Eviden Evidence ce statem statement ent:: lifest lifestyle yle PA is useful useful for weight management. Evidence category B. In modern society, most adults spend most of their time sitting, whether at work, at home, or during leisure time. This leads to low levels of energy expenditure and is likely to be an importa important nt cause cause of the obesit obesity y epidem epidemic ic (61,89,9 (61,89,90,1 0,149). 49). Estimates of the size of the positive energy balance leading to the obesity epidemic range from 10 (149) to 100 kcalIdj1 (61). There are numerous observational studies supporting the hyp hypothe othesis sis that that higher higher levels levels of lifest lifestyle yle PA preven prevent  t  initial weight gain (6,22,25,35,37,46,49,51,124,144). Many of the recent studies include objective measurement of PA  by a variety of methods (6,22,25,37,144), but most of these studi studies es had had a cross cross-s -sec ectio tional nal desi design. gn. Chan Chan et al. al. (17) (17)  provided  provided data from 106 sedentary workers who participated participated in a 12-wk intervention promoting walking. Steps per day were were determ determine ined d by pedome pedometer ters, s, and partic participan ipants ts had an average increase of 3451 steps per day during the course of  the study. There was a greater decrease in waist circumference in those who had a greater increase in steps per day,  but there was no association between BMI and increases in steps. There are several large longitudinal studies that used self-report of PA at baseline as a predictor of weight gain over time (28,35,49,113, (28,35,49,113,124). 124). These studies each include more than 1000 participants, and several years of follow-up. One study from Denmark followed up 21,685 men for 11 yr  (35). There is consistency across the studies showing that  more more active active indi individ viduals uals gained gained less less weight weight or were were less less likely to become obese. However, another cohort of 3653 women and 2626 men in Denmark followed up for 5 yr did not show that inactivity led to obesity but did suggest that  those who became obese also became more inactive (113). Severa Severall experi experimen mental tal trials trials have have include included d a lifes lifestyl tylee approa approach ch to PA withi within n the inter interve venti ntion on (1,2, (1,2,19– 19–21, 21, 36,49,52,71, 36,49,52,71,132,15 132,152,153 2,153). ). In general, general, the interventio interventions ns

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were successful in increasing PA, and this tended to have a   beneficial effect on body weight. Many of these trials were relatively short term; but some lasted 1 yr or more (2,20,36, 71,152), with a notable study by Simkin-Silverman et al. (132) that was carried out for 54 months in 535 premenopausal women. A recent systematic review of studies using   pedome pedometer terss to increa increase se PA provide providess inform informati ation on on how lifestyle PA may affect body weight (12). The investigators reviewed reviewed 26 studies studies on PA programs, 8 of them randomized randomized trials, in which pedometers were used to assess changes in PA. Participants increased their steps per day by more than 2100 in both the randomized trials and the observational studies. Across all studies, participants decreased BMI by 0.38 units (95% confidence interval, 0.05–0.72; P  = 0.03). Although weight loss seems modest, the review does suggest that it is possible to increase lifestyle PA and that this may result in lower weight. The The stud studie iess revi review ewed ed here here includ includee a wide wide varie variety ty of  assessments of PA, diverse populations, and long followup. These characteristics of current research provide strong evidenc evidencee for benefi beneficia ciall effect effectss of lifest lifestyle yle PA in overal overalll weight management. However, there are inherent difficulties ties in making making specif specific ic recomm recommend endati ations ons about about lifest lifestyle yle PA. PA. Firs Firstt is the the lack lack of a cons consist isten entt defin definit itio ion n on what  what  should be included as lifestyle PA. In addition, there are many many differ different ent measur measureme ement nt approa approache chess that that have been been used in the various studies, which make it difficult to provide precise precise inform informatio ation n on specif specific ic amounts amounts of PA that  that  should be recommended recommended.. Nonetheless Nonetheless,, when we consider  consider  the emerging evidence on NEAT and inactivity physiology and the relati relatively vely small small pos positi itive ve energy energy balanc balancee that that has  produced the obesity epidemic, it is reasonable to conclude that increasing lifestyle PA should be a strategy included in weight management efforts. Evidence Evidence statemen statement: t: PA combine combined d with energy  energy  restri res tricti ction on will will increa increase se weight weight loss. loss. Eviden Evidence ce Examination tion of the weight weight loss loss literatu literature re category category A. Examina shows that a reduction in energy intake plays a significant  role role in reduc reducing ing body body weigh weightt and and this this topic topic has has been been extensiv extensively ely reviewe reviewed d (11,50). (11,50). However However,, most recomrecommendations for weight loss include both energy restriction and PA. Weight loss programs can vary dramatically in the amoun amountt of PA used used and and the leve levell of ener energy gy rest restri ricti ction on imposed, with a greater energy deficit producing a greater  weight loss. Most weight loss programs either limit energy intake to a specific amount (e.g., 500–1500 kcal Idj1) regardless of the size or gender of the individuals participating in the program (4,8,9) or select a specific energy deficit  through diet (e.g., (e.g., energy restriction restriction of  j300 kcalIdj1) and/  or exercis exercisee (e.g., (e.g., j300 kcal kcalIdj1) to brin bring g abou aboutt a tota totall j1 energy reduction (e.g., (e.g., j600 kcalId ) (18,39,59,72,96). Virtually all recommendations from public health groups and governmental agencies include the use of PA in con  junc junctio tion n with with diet diet to promo promote te weigh weightt loss loss (57,10 (57,101,1 1,111, 11, 122,145–147). When the energy deficit imposed by diet-only and diet plus PA interventions are similar, weight loss and/or 

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  perc percen entt chan change ge in bod body y weigh weightt are are simi simila larr (4,8, (4,8,18, 18,39, 39, 58,59,72, 58,59,72,82,1 82,103, 03,120, 120,140). 140). When energy energy intake intake is reduced reduced severely, diet and diet and PA groups tend to have similar  results (34). For example, several investigations have used 600–1000 600–1000 kcalIdj1 defic deficits its for 12– 12–16 16 wk, wk, and and the the group group assign assigned ed to PA partic participa ipated ted in three three to five five sessio sessions ns per  week of 30–60 min in duration. Weight loss ranged from È4 to 11 kg (e.g., È1–1 1–1.5 .5 lbIwk j1), regar regardle dless ss of group group asassignment signment (i.e., (i.e., diet-onl diet-only y or diet plus exercise exercise)) (39,72,1 (39,72,140). 40). Thus, the addition of PA to severe diet restriction may result  in metabolic adaptations that diminish any additive effect of  the energy expenditure from PA on weight loss. In studie studiess where where energy energy restri restrictio ction n is not severe severe (i.e., (i.e., 500–700 kcal), there is evidence that diet combined with PA is associ associate ated d with with signific significant antly ly greate greaterr weight weight loss loss compared to diet alone. For example, a recent meta-analysis (128) found a small but significant increase in weight loss in diet plus PA programs of 1.1 kg compared to diet-only   progra programs. ms. Curioni Curioni and Lourenc Lourenco o (23) (23) compar compared ed six ranrandomized clinical trials ranging from 10 to 52 wk that also followed up subjects (n = 265) for 1 yr after the weight loss intervention. They found a 20% greater weight loss in diet    plus plus exerci exercise se program programss (j13 kg) compare compared d to diet-on diet-only ly   programs programs (j9.9 kg) and a 20% greater sustained weight  loss after 1 yr (23). In summary, PA and diet restriction  provide comparable weight loss if they provide similar levels of negative energy balance. It seems PA will increase weight loss in combination with diet restriction if the diet  restriction is moderate but not if it is severe. A thorough review of the diet literature and recommendations for effective diet counseling are available through the American Dietetic Association position paper on weight  management management (in press). press). Exercise Exercise professional professionalss should be cauti cautione oned d rega regardi rding ng the prov provisi ision on of diet dietar ary y advic advicee to overweight and obese adults. In particular, caution is advised when chronic disease risk factors or known chronic disease disease are present. Providing specific diet recommendarecommendations may be outside the scope of practice for the exercise   professional, and the appropriate course of action may require referral to a registered dietitian. Evidence statement: Resistance training will not promote clinically significant weight loss. Evidence category A. The ACSM Position Stand ‘‘Appropriate Intervent tervention ion Strate Strategie giess for Weight Weight Loss Loss and Preven Prevention tion of  Weight Regain for Adults’’ Adults’’ (68) emphasized emphasized diet restricrestriction and enduran endurance ce exerci exercise. se. Resist Resistanc ancee traini training ng was not  assigned assigned a major role by the authors because because it was believed believed that evidence for the efficacy of weight training for weight  loss and maintenance maintenance was insufficient insufficient.. Although the energy energy expenditure associated with resistance training is not large, resistance resistance training may increase increase muscle mass which may in turn turn increa increase se 24-h energy energy expend expenditur iture. e. Figure Figure 1 reprepresents a model that may reflect a role for resistance training in weight weight management management.. Less research has been conducted using resistance training as part of an exercise intervention compared to aerobic

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FIGURE 1—Conceptual model of resistance training and the potential effect on energy expenditure. A conceptual model that includes both the energy expenditure expenditure from increased increased muscle mass and the potential potential energy expenditure from increased activities activities of daily living. RMR, resting metabolic rate.

exercise. This may be caused by the diminished energy and fat use compared to aerobic exercise during a typical session of the same same durat duration ion.. Howeve However, r, diffe differe rence ncess in hormo hormonal nal response to resistance exercise (potential for acute stimulation of metabolic metabolic rate and fat oxidation oxidation after after the activity) activity) and enhancement of muscle protein balance (potential to chronically increase total energy expenditure) provide some justification for the examination of benefits on body weight and composition. Studies evaluating the effect of resistance training on body weight and composition are summarized below. There is less evidence for the effect of resistance exercise on   body composition than body weight because some studies did not assess body composition.  Neither randomized controlled (42,108,123,125) nor intervent tervention ion studie studiess without without a sedenta sedentary ry compar comparison ison group group (63,66,79,88,115) provide evidence for a reduction in body weight when resistance training is performed without any modification of diet. However, the studies since 1999 are equally equally split split concer concerning ning whethe whetherr resist resistanc ancee trainin training g will will caus causee a loss loss of bod body y fat. fat. Some Some stud studie iess repor reportt a mo mode dest  st  reducti reduction on in body fat (63,66,8 (63,66,88,12 8,125) 5) when when resist resistanc ancee traini training ng was was contin continue ued d for 16– 16–26 26 wk, wk, where whereas as oth other erss repor reporte ted d no effe effect ct on bod body y fat fat for inter interve vent ntion ionss of 12–  12–  52 wk in duration (44,88,108,115). (44,88,108,115). It is noteworthy noteworthy that one study study (88) (88) repo reporte rted d a diffe differe rent ntia iall resp respons onsee on bod body y fat  fat  depending on age and gender; reduction in body fat was observed only for older men with no effect for young men or young or old women. Slightly more studies reported an incre increas asee in lean lean mass mass afte afterr resi resista stance nce train training ing witho without  ut  modification modification of diet (63,64,108,125) (63,64,108,125) than those reporting no effect effect (44,11 (44,115,12 5,123). 3). Some Some of the differ differenc ences es among among studies could be secondary to differences in body composition technique used, duration of intervention, or specific exercise exercise prescription. prescription. Combining resistance resistance training training with aerobic training has been shown to be superior for body weight and fat loss (3,110) (3,110) and to result in greater greater lean body mass mass (110) (110) when when compar compared ed to aerobic aerobic exercise exercise alone alone in several randomized controlled trials but not others (26). When resistance training is added to a reduced energy intake intake interve interventio ntion, n, the energy energy restri restrictio ction n seems seems to overover-

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shadow shadow the the resi resist stan ance ce trai trainin ning. g. None None of the rece recent ntly ly  performed randomized controlled trials (73,75,82,117) observed a greater body weight loss for interventions lasting from 4 to 16 wk. Most studies did not detect greater body fat loss with resistance training over energy restriction alone (75,82,117), although one study (73) examined body fat at  various various sites sites using using magnet magnetic ic resonan resonance ce imagin imaging g and re  ported a superior loss of subcutaneous body fat with the combina combinatio tion n of resist resistanc ancee trainin training g with with diet diet compar compared ed to diet diet modific modificati ation on alone. alone. On the other other hand, hand, most most studie studiess combining resistance training with energy restriction report  impr improv oved ed lean lean body body mass mass comp compar ared ed to diet dietin ing g alon alonee (73,75,82,117). Only Only two recent recent random randomize ized d contro controlled lled studie studiess have have examined the effect of resistance exercise on prevention of  weight gain or regain after weight loss (84,123). One study demons demonstrat trated ed no differ differenc encee in weight weight regain regain during during a 6month period after a very low energy diet for 90 subjects assigned to walking, resistance training, or no exercise (84). A larg larger er group group of subj subjec ects ts (n = 164 164)) was was recr recruit uited ed for  evaluation of regular resistance training to prevent gain in fat mass for 2 yr (123). No differences were noted in body weight change during this period; however, total body fat  decreased more and intra-abdominal fat increased less for  the treatment group compared to the control. There There is a pot potent ential ially ly intere interesti sting ng interac interaction tion betwee between n resistance training and dietary protein in interventions with overweight overweight individuals. individuals. Two randomized randomized controlled controlled trials compared the effects of resistance training when combined with diets that varied in protein content (31,86). The higher   protein intervention was superior for either body weight and total fat lost (86) or prevention of lean tissue loss (31). In one study, this was accomplished through a doubling of the over overal alll prot protei ein n cont conten entt of the the diet diet to 1.6 1.6 gIkgj1 (86), whereas whereas the other (31) used a high-protein high-protein supplement supplement (10 g  protein)  protein) immediately immediately after each resistance workout. There is little literature and no clear pattern for outcomes of weig weight ht and and body body comp compos osit itio ion n when when the the dose dose for  for  resistance training has varied. Only two recent randomized controlled controlled studies studies compared compared different different resistance resistance protocols

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within one study (15,26). Campbell et al. (15) compared obese subjects who performed whole-body resistance exercise for 11 wk to those who did only lower-body resistance exercises. There was no difference in the effect of the two exerci exercise se plans plans on body compos compositio ition. n. Simila Similarly, rly, no difdifference ference in body weight or composition change was noted by Delecluse et al. (26) when comparing moderate- (two sets of 20 repetition maximum (RM) increasing to 8 RM over  time) to a low- (two sets of 30 RM) intensity resistance  protocol for 20 wk. Altho Although ugh the effe effect ctss of resis resista tance nce traini training ng on bod body y weight and composition may be modest, resistance training has been associated associated with improvements improvements in CVD risk factors factors in the absence of significant weight loss. Resistance training has been shown to increase HDL-C (65), decrease LDL-C (54,65), (54,65), and decrea decrease se TG (54). (54). Improve Improvemen ments ts in insulin insulin sensiti sensitivity vity (29,66) (29,66) and reducti reductions ons in glucoseglucose-sti stimul mulate ated d  plasma insulin concentrations (65) have been reported after  resistance resistance training. Reductions Reductions in both systolic and diastolic diastolic   blood blood pressu pressure re have have also also been been reporte reported d after after resist resistanc ancee training training (77,106). (77,106). In summ summar ary, y, resi resist stan ance ce trai traini ning ng does does not not seem seem to be effective for weight reduction in the order of 3% of initial weight weight and does does not add to weight weight loss when when combine combined d with diet restriction. Resistance training increases fat-free mass when used alone or in combination with weight loss from diet restriction. Resistance training may increase loss of fat mass when combined combined with aerobic exercise compared compared to resistance training alone. No evidence currently exists for   prevention of weight regain after weight loss or for a dose effect for resistance training and weight loss. PA, weight, and chronic disease risk factors. This   po posi siti tion on pape paperr is prim primar arily ily focu focuse sed d on PA and and weigh weight; t; however, it should be acknowledged that there are benefits shown for PA whether weight is lost and perhaps even if  weig weight ht is gain gained ed.. For For exam example ple,, data data from from longi longitu tudin dinal al studies such as The Coronary Artery Risk Development in Young Adults Study (CARDIA) (91,105), the Atherosclerosis Risk in Communities Communities Cohort (141–143), and the FELS Longitudinal Longitudinal Study (127,130,131) (127,130,131) provide evidence that the  prevention  prevention of weight gain may be the easiest way to prevent  prevent  the development of undesirable changes in CVD risk factors (i.e., (i.e., increas increased ed LDL-C, LDL-C, total total choleste cholesterol, rol, TG, fasting fasting glucose glucose,, and decrea decreased sed HDL-C) HDL-C).. Long-ter Long-term m data data (15 yr) from the CARDIA CARDIA study (91) (91) indi indicat catee that that regardl regardless ess of  BMI, individuals that maintain a stable BMI minimized the undes und esira irabl blee chan change gess in CVD CVD risk risk fact factors ors that that may may be associated associated with aging. Benefits of PA for the reduction of chronic health risks are seen with minimal weight loss of less than 3%. For  example, Donnelly et al. (33) randomized sedentary, moderately obese females to 18 months of either continuous or  intermittent exercise. After 18 months of exercise, weight  loss was È2% in the continuous group and È1% in the intermittent group. Despite the minimal weight loss, both groups groups had signif significa icant nt imp improv rovem ement entss in HDL-C HDL-C and

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reduced insulin area under the curve after an oral glucose toleran tolerance ce test. test. Kraus Kraus et al. (83) (83) random randomize ized d sedent sedentary ary,, overweight men and women to either a control group, a  high-am high-amount ount,, hig high-in h-intens tensity ity group, group, a low-amo low-amount, unt, hig highhintensity group, or a low-amount, moderate-intensity group. ˙ O2max in the Inte Intens nsit itie iess rang ranged ed from from 40% 40% to 55% 55% V the ˙ O2max modera moderatete-int intensi ensity ty group group and from from 65% to 80% V in the high-intensity groups. Despite minimal weight (G2%) loss in all groups, groups, there there were were signif significa icant nt benefi beneficia ciall decdecreases in TG and increases in HDL-C. Cons Consid ider ering ing that that mo most st of the adul adultt pop popul ulat ation ion gains gains weight across time, it is important to determine whether PA attenuates undesirable changes in chronic disease risk factors across time. Data from longitudinal longitudinal observational observational studies indicate an association between PA and an attenuation of risk risk across across time. In the Healthy Healthy Women Women Study Study (109), (109), j1 women who increased PA by Q300 kcalIwk  had basically no change HDL-C during a 3-yr period compared compared to women j1 who decreased PA by Q300 kcalIwk  had a 1.9-mgIdLj1 decrease in HDL-C. Data from Nurse’s Health Study (62) examin examined ed the associa associatio tion n of sedent sedentary ary behavi behavior or and teletelevision watching to the risk of obesity and type 2 diabetes during a 6-yr period. Minimal activity (walking around the house 2 hIdj1) was associated with 9% reduction in obesity and a 12% reduction in type 2 diabetes and walking 1 hIdj1 was was asso associ ciat ated ed with with a 24% reduc reducti tion on in obes obesit ity y and and a  34% reduction reduction in typ typee 2 diabet diabetes. es. A lim limita itation tion of these these studies is that they are observational in nature and the PA is self-reported. Few randomi randomized zed control controlled led trials trials have have examin examined ed the rela relatio tions nshi hip p betw betwee een n PA and and weigh weightt gain gain.. Of the the few few available that measure CVD risk factors, they examine this relationship in individuals that are at risk for weight gain and utilize interventions that are a combination of PA and nutrition (13,100). Thus, there is not enough literature to determine determine whether whether PA prevents prevents or attenuates attenuates detrimental detrimental changes in chronic disease risk factors during weight gain and such studie studiess are needed. needed. In summar summary, y, it seems seems that  minimal minimal amounts amounts of PA imp improve rove many chronic chronic disease disease risk factors. However, there are few published literature on the time course of these improvements; the permanence of  these improvements over time, if there are diminishing returns for the amount of weight lost, and the ability of the PA to improve or attenuate increases in chronic risk factors during weight gain are poorly understoo understood d and merit  investigation. CONCLUSIONS Moderate-intensity PA of 150 to 250 minIwk j1 with an energy equivalent of  È1200 to 2000 kcalIwk j1 seems sufficien ficientt to prev preven entt weig weight ht gain gain grea greate terr than than 3% in mo most  st  adults and may result in modest weight loss. PA without  diet restriction restriction generally generally provides modest weight loss; however, laboratory studies that provide supervision and greater  doses of PA compared to outpatient studies tend to show

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weight loss at or above 3% of initial weight. PA combined with diet restriction provides a modest addition of weight  loss compared to diet alone, and this additive effect is diminished as the level of diet restriction increases. There are cross-sectional and prospective data that PA is associated with prevention of weight regain after weight loss; however, ever, there there are are no approp appropria riatel tely y design designed, ed, random randomize ized d controlled trials to indicate whether PA is effective for the   prevention of weight regain and no information regarding the existence of a potential dose effect. Lifestyle approaches for incr increa easi sing ng PA and and plann planned ed PA are are cons consis iste tent ntly ly associ associate ated d with with less less weight weight gain gain compare compared d to inacti inactivity vity.. The effects of lifestyle PA for prevention of weight regain after weight loss are unknown owing to lack of available literature. The effects of resistance training for prevention of  weight gain are largely unknown owing to lack of available liter literat ature ure.. Resi Resist stanc ancee train trainin ing g does does not seem seem to be an effe effect ctive ive mean meanss for weigh weightt loss loss but is asso associ ciat ated ed with with numerous numerous other health benefits including decreases decreases in many chronic disease risk factors and increases in fat-free mass and decreases in fat mass. Weight maintenance compared to weight gain seems to protect against an increase in chronic disease disease risk factor factors, s, and in many many studie studies, s, weight weight loss as little as 3% has been associated with favorable changes in chronic disease risk factors.

On the basis of the available scientific scientific literature, the ACSM recom recomme mends nds that that adults adults parti particip cipate ate in at leas leastt 150 minIwk j1 of  moderate moderate-int -intensi ensity ty PA to prevent prevent signific significant ant weight weight gain and reduc reducee assoc associat iated ed chron chronic ic disea disease se risk risk fact factors ors.. It is recommended that overweight and obese individuals participate in this level of PA to elicit modest reductions in body weight. However, there is likely a dose effect of PA, with greate greaterr weigh weightt loss loss and enhanc enhanced ed preve preventi ntion on of weigh weight  t  regain regained ed with with dos doses es of PA that that appro approxim ximate ate 250 to 300 j1 j1 minIwk  (approxi (approximate mately ly 2000 kcalIwk  ) of moder moderat ateeintensity PA.

These recommendations are consistent with the recent publication of the US Department of Health and Human Services Physical  Activity Guidelines for Americans and the accompanying Advisory Committee Report (http://www.health.go (http://www.health.gov/PAGuidelines/Repo v/PAGuidelines/Report/  rt/  Default.aspx). This pronouncement pronouncement was reviewed reviewed for the American American College of  Sports Medicine by the ACSM Pronouncements Committee and by Ross Ross E. Ander Anderse sen, n, Ph.D Ph.D., ., Jame James s D. Dziur Dziura, a, Ph.D Ph.D., ., Jame James s O. Hill, Hill, Ph.D Ph.D., ., Laura J. Kurskall, Ph.D., FACSM, and Robert Ross, Ph.D. This Position Position Stand Stand replaces replaces the 2001 Position Stand, ‘‘ApproAppropriate priate Interve Interventio ntion n Strateg Strategies ies for Weight Weight Loss Loss and Prevent Prevention ion of Weight Weight Regain Regain for Adults’’ [ Med Med Sci Sports Exerc. 2001;33(12): 2145–56].

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WEIGHT LOSS AND PREVENTION OF WEIGHT REGAIN

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