Obesity: Jakicic JM

Donnelly JE, Blair SN, Jakicic JM, Manore MM, Rankin JW, Smith BK, Anonymous00019. · No affiliation provided · Med Sci Sports Exerc. · Pubmed #19127177 No free full text.

Abstract: 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 Institute (NHLBI) encourage a 10% reduction in weight, although considerable literature indicates reduction in health risk with 3% to 5% reduction in weight. Physical activity (PA) is recommended as a component of weight management for prevention of weight gain, for weight loss, and for prevention of weight regain after weight loss. In 2001, the American College of Sports Medicine (ACSM) published a Position Stand that recommended a minimum of 150 min wk(-1) of moderate-intensity PA for overweight and obese adults to improve health; however, 200-300 min wk(-1) was 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 moderate-intensity PA between 150 and 250 min wk(-1) to be effective to prevent weight gain. Moderate-intensity PA between 150 and 250 min wk(-1) will provide only modest weight loss. Greater amounts of PA (>250 min wk(-1)) have been associated with clinically significant weight loss. Moderate-intensity PA between 150 and 250 min wk(-1) will improve weight loss in studies that use moderate diet restriction but not severe diet restriction. Cross-sectional and prospective studies indicate that after weight loss, weight maintenance is improved with PA >250 min wk(-1). 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 training does not 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 without weight loss improves health risk. There is inadequate evidence to determine whether PA prevents or attenuates detrimental changes in chronic disease risk during weight gain.

Jakicic JM, Otto AD. · Department of Health and Physical Activity, Physical Activity and Weight Management Research Center, University of Pittsburgh, 140 Trees Hall, Pittsburgh, PA 15261, USA. · Nutr Rev. · Pubmed #16532900 No free full text.

Abstract: The increasing prevalence of overweight and obesity highlight the need for improved intervention strategies to counteract this significant public health problem. To this end, it appears that increases in energy expenditure through exercise and other forms of physical activity may be an important component of effective interventions to enhance initial weight loss and the prevention of weight regain. However, to achieve these outcomes, adequate levels of exercise and physical activity appear to be necessary, with 60 to 90 min/d currently being recommended. While this appears to be a significant amount of activity, overweight and obese adults should be counseled to progressively increase to these levels of exercise and physical activity. Moreover, there is significant evidence that even if an overweight or obese adult is unable to achieve this level of activity, that significant health benefits can be realized by participating in at least 30 minutes of daily activity that is at least moderate in intensity. Therefore, it is important to have interventions that target these levels of physical activity to improve health-related outcomes and to facilitate long-term weight control.

Jakicic JM, Otto AD. · University of Pittsburgh Department of Health and Physical Activity and Weight Management Research Center, Pittsburgh, PA 15261, USA. · Am J Clin Nutr. · Pubmed #16002826 links to  free full text

Abstract: Overweight and obesity present significant public health concerns because of the link with numerous chronic health conditions. Excess body weight is a result of an imbalance between energy intake and energy expenditure. Physical activity is the most variable component of energy expenditure and therefore has been the target of behavioral interventions to modify body weight. It appears that physical activity is an important component on long-term weight control, and therefore adequate levels of activity should be prescribed to combat the obesity epidemic. Although there is evidence that 30 min of moderate-intensity physical activity may improve health outcomes, the amount of physical activity that may be necessary to control body weight may be >30 min/d. There is a growing body of scientific literature suggesting that at least 60 min of moderate-intensity physical activity may be necessary to maximize weight loss and prevent significant weight regain. Moreover, adequate levels of physical activity appear to be important for the prevention of weight gain and the development of obesity. Physical activity also appears to have an independent effect on health-related outcomes when compared with body weight, suggesting that adequate levels of activity may counteract the negative influence of body weight on health outcomes. Thus, it is important to target intervention strategies to facilitate the adoption and maintenance of an adequate amount of physical activity to control body weight.

Jakicic JM, Otto AD. · University of Pittsburgh, Department of Health and Physical Activity, Physical Activity and Weight Management Research Center, 140 Trees Hall, Pittsburgh, PA 15261, USA. · Psychiatr Clin North Am. · Pubmed #15733616 No free full text.

This publication has no abstract.

Jakicic JM. · Department of Health, Physical, and Recreation Activity, Weight Management Research Center, University of Pittsburgh, 104 Trees Hall, Pittsburgh, PA 15261, USA. · Endocrinol Metab Clin North Am. · Pubmed #14711070 No free full text.

Abstract: Exercise is an important component of behavioral weight control interventions, and exercise may be most effective for weight control when combined with modifications to energy intake. Clinicians should initially encourage overweight and obese adults to adopt at least 150 minutes of moderate-intensity exercise per week (30 min x 5 d/wk), because this level of exercise has been shown to improve health-related outcomes. Higher levels of exercise, however, may be necessary to enhance long-term weight loss and to facilitate weight loss maintenance. It is now recommended that exercise be progressively increased to approximately 300 minutes per week (60 min x 5 d/wk) to optimize the impact of exercise on body weight regulation. Adoption of this high level of exercise may be challenging, however, and therefore clinicians should counsel patients to incorporate intermittent and lifestyle approaches for exercise to maximize adherence. Moreover, devices such as pedometers may facilitate goal-setting and self-monitoring of exercise, and these are critical components of effective behavioral interventions. Incorporation of these recommendations may increase the likelihood of clinicians' prescribing exercise for overweight and obese adults to effectively manage their body weight.

Jakicic JM. · Physical Activity and Weight Management Research Center, Department of Health, Physical, and Recreation Education, University of Pittsburgh, 140 Trees Hall, Pittsburgh, PA 15261, USA. · Prim Care. · Pubmed #14567155 No free full text.

Abstract: Exercise is an important component of weight-control programs, yet the impact of exercise for weight control is based on the ability of patients to engage in adequate levels of activity. The minimal level that should be recommended is at least 30 minutes of moderate-intensity physical activity on most days of the week. Although this level of physical activity may improve health-related factors, there is some evidence to support the recommendation of higher levels of exercise for weight-control purposes. The role of the clinician is to provide adequate guidance to patients regarding issues related to the intensity, duration, and mode of exercise that may be most appropriate. When addressing these issues, it is also important to consider the barriers that individual patients may encounter that will have an effect on adoption and maintenance of exercise behaviors.

Jakicic JM, Clark K, Coleman E, Donnelly JE, Foreyt J, Melanson E, Volek J, Volpe SL, Anonymous00056. · American College of Sports Medicine. · Med Sci Sports Exerc. · Pubmed #11740312 No free full text.

Abstract: In excess of 55% of adults in the United States are classified as either overweight (body mass index = 25-29.9 kg.m(-2)) or obese (body mass index > or = 30 kg.m(-2)). To address this significant public health problem, the American College of Sports Medicine recommends that the combination of reductions in energy intake and increases in energy expenditure, through structured exercise and other forms of physical activity, be a component of weight loss intervention programs. An energy deficit of 500-1000 kcal.d-1 achieved through reductions in total energy intake is recommended. Moreover, it appears that reducing dietary fat intake to <30% of total energy intake may facilitate weight loss by reducing total energy intake. Although there may be advantages to modifying protein and carbohydrate intake, the optimal doses of these macronutritents for weight loss have not been determined. Significant health benefits can be recognized with participation in a minimum of 150 min (2.5 h) of moderate intensity exercise per week, and overweight and obese adults should progressively increase to this initial exercise goal. However, there may be advantages to progressively increasing exercise to 200-300 min (3.3-5 h) of exercise per week, as recent scientific evidence indicates that this level of exercise facilitates the long-term maintenance of weight loss. The addition of resistance exercise to a weight loss intervention will increase strength and function but may not attenuate the loss of fat-free mass typically observed with reductions in total energy intake and loss of body weight. When medically indicated, pharmacotherapy may be used for weight loss, but pharmacotherapy appears to be most effective when used in combination with modifications of both eating and exercise behaviors. The American College of Sports Medicine recommends that the strategies outlined in this position paper be incorporated into interventions targeting weight loss and the prevention of weight regain for adults.

Wing RR, Goldstein MG, Acton KJ, Birch LL, Jakicic JM, Sallis JF, Smith-West D, Jeffery RW, Surwit RS. · Weight Control and Diabetes Research Center, Miriam Hospital, Brown University, Providence, Rhode Island 02906, USA. · Diabetes Care. · Pubmed #11194216 links to  free full text

Abstract: Lifestyle factors related to obesity, eating behavior, and physical activity play a major role in the prevention and treatment of type 2 diabetes. In recent years, there has been progress in the development of behavioral strategies to modify these lifestyle behaviors. Further research, however, is clearly needed, because the rates of obesity in our country are escalating, and changing behavior for the long term has proven to be very difficult. This review article, which grew out of a National Institute of Diabetes and Digestive and Kidney Diseases conference on behavioral science research in diabetes, identifies four key topics related to obesity and physical activity that should be given high priority in future research efforts: 1) environmental factors related to obesity, eating, and physical activity; 2) adoption and maintenance of healthful eating, physical activity, and weight; 3) etiology of eating and physical activity; and 4) multiple behavior changes. This review article discusses the significance of each of these four topics, briefly reviews prior research in each area, identifies barriers to progress, and makes specific research recommendations.

Jakicic JM, Marcus BH, Gallagher KI, Napolitano M, Lang W. · University of Pittsburgh, Physical Activity and Weight Management Research Center, Pittsburgh, PA 15261, USA. · JAMA. · Pubmed #12966123 links to  free full text

Abstract: CONTEXT: A higher duration and intensity of exercise may improve long-term weight loss. OBJECTIVE: To compare the effects of different durations and intensities of exercise on 12-month weight loss and cardiorespiratory fitness. DESIGN, SETTING, AND PARTICIPANTS: Randomized trial conducted from January 2000 through December 2001 involving 201 sedentary women (mean [SD] age, 37.0 [5.7] years; mean [SD] body mass index, 32.6 [4.2]) in a university-based weight control program. INTERVENTION: Participants were randomly assigned to 1 of 4 exercise groups (vigorous intensity/high duration; moderate intensity/high duration; moderate intensity/moderate duration; or vigorous intensity/moderate duration) based on estimated energy expenditure (1000 kcal/wk vs 2000 kcal/wk) and exercise intensity (moderate vs vigorous). All women were instructed to reduce intake of energy to between 1200 and 1500 kcal/d and dietary fat to between 20% and 30% of total energy intake. MAIN OUTCOME MEASURES: Body weight, cardiorespiratory fitness, and exercise participation. RESULTS: After exclusions, 184 of 196 randomized participants completed 12 months of treatment (94%). In intention-to-treat analysis, mean (SD) weight loss following 12 months of treatment was statistically significant (P <.001) in all exercise groups (vigorous intensity/high duration = 8.9 [7.3] kg; moderate intensity/high duration = 8.2 [7.6] kg; moderate intensity/moderate duration = 6.3 [5.6] kg; vigorous intensity/moderate duration = 7.0 [6.4] kg), with no significant difference between groups. Mean (SD) cardiorespiratory fitness levels also increased significantly (P =.04) in all groups (vigorous intensity/high duration = 22.0% [19.9%]; moderate intensity/high duration = 14.9% [18.6%]; moderate intensity/moderate duration = 13.5% [16.9%]; vigorous intensity/moderate duration = 18.9% [16.9%]), with no difference between groups. Post hoc analysis revealed that percentage weight loss at 12 months was associated with the level of physical activity performed at 6 and 12 months. Women reporting less than 150 min/wk had a mean (SD) weight loss of 4.7% [6.0%]; inconsistent (other) pattern of physical activity, 7.0% [6.9%]; 150 min/wk or more, 9.5% [7.9%]; and 200 min/wk or more of exercise, 13.6% [7.8%]. CONCLUSIONS: Significant weight loss and improved cardiorespiratory fitness were achieved through the combination of exercise and diet during 12 months, although no differences were found based on different exercise durations and intensities in this group of sedentary, overweight women.

Donnelly JE, Hill JO, Jacobsen DJ, Potteiger J, Sullivan DK, Johnson SL, Heelan K, Hise M, Fennessey PV, Sonko B, Sharp T, Jakicic JM, Blair SN, Tran ZV, Mayo M, Gibson C, Washburn RA. · Energy Balance Laboratory, Schiefelbusch Life Span Institute, University of Kansas, Lawrence 66045, USA. · Arch Intern Med. · Pubmed #12796071 links to  free full text

Abstract: BACKGROUND: In light of the current obesity epidemic, treatment models are needed that can prevent weight gain or provide weight loss. We examined the long-term effects of a supervised program of moderate-intensity exercise on body weight and composition in previously sedentary, overweight and moderately obese men and women. We hypothesized that a 16-month program of verified exercise would prevent weight gain or provide weight loss in the exercise group compared with controls. METHODS: This was a randomized controlled efficacy trial. Participants were recruited from 2 midwestern universities and their surrounding communities. One hundred thirty-one participants were randomized to exercise or control groups, and 74 completed the intervention and all laboratory testing. Exercise was supervised, and the level of energy expenditure of exercise was measured. Controls remained sedentary. All participants maintained ad libitum diets. RESULTS: Exercise prevented weight gain in women and produced weight loss in men. Men in the exercise group had significant mean +/- SD decreases in weight (5.2 +/- 4.7 kg), body mass index (calculated as weight in kilograms divided by the square of height in meters) (1.6 +/- 1.4), and fat mass (4.9 +/- 4.4 kg) compared with controls. Women in the exercise group maintained baseline weight, body mass index, and fat mass, and controls showed significant mean +/- SD increases in body mass index (1.1 +/- 2.0), weight (2.9 +/- 5.5 kg), and fat mass (2.1 +/- 4.8 kg) at 16 months. No significant changes occurred in fat-free mass in either men or women; however, both had significantly reduced visceral fat. CONCLUSIONS: Moderate-intensity exercise sustained for 16 months is effective for weight management in young adults.

Jakicic JM, Winters C, Lang W, Wing RR. · Miriam Hospital, Brown University School of Medicine, Providence, RI 02906, USA. · JAMA. · Pubmed #10546695 links to  free full text

Abstract: CONTEXT: Enhancing participation in long-term exercise may translate into improved long-term weight loss in overweight adults. OBJECTIVES: To compare the effects of intermittent with traditional continuous exercise on weight loss, adherence, and fitness, and to examine the effect of combining intermittent exercise with that using home exercise equipment. DESIGN: Randomized trial from September 1996 through September 1998. SETTING AND PARTICIPANTS: A total of 148 sedentary, overweight (mean [SD] body mass index, 32.8 [4.0] kg/m2) women (mean [SD] age, 36.7 [5.6] years) in a university-based weight control program. INTERVENTIONS: Eighteen-month behavioral weight control program with 3 groups: long-bout exercise (LB), multiple short-bout exercise (SB), or multiple short-bout exercise with home exercise equipment (SBEQ) using a treadmill. MAIN OUTCOME MEASURES: Body weight, body composition, cardiorespiratory fitness, and exercise adherence. RESULTS: Of 148 subjects, 115 (78%) completed the 18-month program. At 18 months, mean (SD) weight loss was significantly greater in subjects in the SBEQ group compared with subjects in the SB group (-7.4 [7.8] kg vs -3.7 [6.6] kg; P<.05). Mean (SD) weight loss for subjects in the LB group (-5.8 [7.1] kg) was not significantly different than for subjects in the SB or SBEQ groups. Subjects in the SBEQ group maintained a higher level of exercise than subjects in both the SB and LB groups (P<.05) at 13 to 18 months of treatment. All groups showed an increase in cardiorespiratory fitness from baseline to 18 months, with no difference between groups. Mean (SD) weight loss at 18 months was significantly greater in individuals exercising more than 200 min/wk throughout the intervention (-13.1 [8.0] kg) compared with individuals exercising 150 to 200 min/wk (-8.5 [5.8] kg) or less than 150 min/wk (-3.5 [6.5] kg) (P<.05). CONCLUSIONS: Compared with the LB group, subjects in the SB group did not experience improved long-term weight loss, exercise participation, or cardiorespiratory fitness. Access to home exercise equipment facilitated the maintenance of SB, which may improve long-term weight loss. A dose-response relationship exists between amount of exercise and long-term weight loss in overweight adult women.

Fleet-Michaliszyn SB, Soreca I, Otto AD, Jakicic JM, Fagiolini A, Kupfer DJ, Goodpaster BH. · College of Nursing, University of Arizona, Tucson, USA. · J Clin Psychiatry. · Pubmed #19026257 No free full text.

Abstract: OBJECTIVE: Patients with bipolar disorder are at increased risk for diabetes and cardiovascular diseases, possibly because of more severe insulin resistance. The primary purpose of this study was to determine whether insulin resistance is characteristic of bipolar disorder. METHOD: The Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) was performed in 18 women with DSM-IV bipolar I disorder, and results were compared to those of 17 matched controls. Other risk factors were compared, including blood pressure, blood lipids, and abdominal obesity by computed tomography (CT). Additionally, substrate utilization was measured by indirect calorimetry, and free-living energy expenditure was estimated using wearable activity monitors. All data were collected between February 2006 and December 2007. RESULTS: Patients with bipolar disorder were no more insulin resistant than controls after accounting for generalized obesity (mean +/- SEM HOMA-IR = 2.7 +/- 0.7 vs. 2.5 +/- 0.7, for patients and controls, respectively; p = .79). Although blood lipid profiles were generally similar in patients and controls, obese patients had higher blood pressure than controls. Obese patients had more mean +/- SEM total abdominal fat (718.1 +/- 35.1 cm(2 )vs. 607.4 +/- 33.6 cm(2); p = .04), and tended (p = .06) to have more visceral abdominal fat. Patients oxidized 13% less fat during resting conditions, although their resting metabolic rate was similar to that of controls. CONCLUSION: Women with bipolar I disorder were no more insulin resistant than matched controls after accounting for their level of obesity. However, they were more hypertensive, had higher amounts of abdominal obesity, and had reduced rates of fat oxidation. Therefore, women with bipolar I disorder may be at a heightened risk for future weight gain and concomitant risk for diabetes and cardiovascular disease.

Gorin AA, Wing RR, Fava JL, Jakicic JM, Jeffery R, West DS, Brelje K, Dilillo VG, Anonymous00005. · Department of Psychology, Center for Health, Intervention and Prevention, University of Connecticut, Storrs, CT, USA. · Int J Obes (Lond). · Pubmed #18762804 No free full text.

Abstract: OBJECTIVES: To examine whether a weight loss program delivered to one spouse has beneficial effects on the untreated spouse and the home environment. METHODS: We assessed untreated spouses of participants in three sites of Look AHEAD, a multicenter randomized controlled trial evaluating the impact of intentional weight loss on cardiovascular outcomes in overweight individuals with type 2 diabetes. Participants and spouses (n=357 pairs) were weighed and completed measures of diet and physical activity at 0 and 12 months. Spouses completed household food and exercise environment inventories. We examined differences between spouses of participants assigned to the intensive lifestyle intervention (ILI) or to the enhanced usual care (DSE; diabetes support and education). RESULTS: Spouses of ILI participants lost -2.2+/-4.5 kg vs -0.2+/-3.3 kg in spouses of DSE participants (P<0.001). In addition, more ILI spouses lost > or =5% of their body weight than DSE spouses (26 vs 9%, P<0.001). Spouses of ILI participants also had greater reductions in reported energy intake (P=0.007) and percent of energy from fat (P=0.012) than DSE spouses. Spouse weight loss was associated with participant weight loss (P<0.001) and decreases in high-fat foods in the home (P=0.05). CONCLUSION: The reach of behavioral weight loss treatment can extend to a spouse, suggesting that social networks can be utilized to promote the spread of weight loss, thus creating a ripple effect.

Helsel DL, Jakicic JM, Otto AD. · Department of Sports Medicine and Nutrition, Physical Activity and Weight Management Research Center, University of Pittsburgh, PA 15260, USA. · J Am Diet Assoc. · Pubmed #17904942 No free full text.

Abstract: This study examined whether different methods of self-monitoring eating and exercise behaviors affect the process of self-monitoring and change in body weight in overweight adults. Forty-two subjects participated in a 16-week correspondence-based weight-loss intervention using a pretest-posttest randomized design. Dietary intake was prescribed at 1,200 to 1,500 kcal/day and <30% dietary fat. Physical activity was progressed to 200 minutes/week. Participants were randomly assigned to self-monitoring eating and physical activity behaviors using a traditional detailed method or transitioning to an abbreviated method. Transitioning to an abbreviated method returned significantly more diaries than using a traditional detailed method (P=0.04). Participants completing the study showed no significant difference in weight loss between the traditional detailed method (-7.5+/-5.3 kg) and the abbreviated method (-7.6+/-5.5 kg), with similar results for intention-to-treat analysis (detailed method -3.9+/-5.3 kg vs abbreviated method -4.3+/-5.8 kg). Weight loss was significantly associated with number of self-monitoring diaries completed (r=0.53, P<0.05). Findings suggest the self-monitoring process, rather than the detail of self-monitoring, is important for facilitating weight loss and change in eating and physical activity behaviors. Transitioning to a simplified approach to self-monitoring does not negatively affect short-term weight loss in overweight adults. These results may have implications for improving self-monitoring in overweight adults during periods of weight loss.

Ribisl PM, Lang W, Jaramillo SA, Jakicic JM, Stewart KJ, Bahnson J, Bright R, Curtis JF, Crow RS, Soberman JE, Anonymous00252. · Health and Exercise Sciences, Department of Biostatistical Sciences, Wake Forest University, Wake Forest Road, Winston-Salem, NC 27109, USA. · Diabetes Care. · Pubmed #17644623 links to  free full text

Abstract: OBJECTIVE: We examined associations of cardiovascular, metabolic, and body composition measures with exercise capacity using baseline data from 5,145 overweight and/or obese (BMI > or = 25.0 kg/m2) men and women with type 2 diabetes who were randomized participants for the Look AHEAD (Action for Health in Diabetes) clinical trial. RESEARCH DESIGN AND METHODS: Peak exercise capacity expressed as METs and estimated from treadmill speed and grade was measured during a graded exercise test designed to elicit a maximal effort. Other measures included waist circumference, BMI, type 2 diabetes duration, types of medication used, A1C, history of cardiovascular disease, metabolic syndrome, beta-blocker use, and race/ethnicity. RESULTS: Peak exercise capacity was higher for men (8.0 +/- 2.1 METs) than for women (6.7 +/- 1.7 METs) (P < 0.001). Exercise capacity also decreased across each decade of age (P < 0.001) and with increasing BMI and waist circumference levels in both sexes. Older age, increased waist circumference and BMI, a longer duration of diabetes, increased A1C, a history of cardiovascular disease, having metabolic syndrome, beta-blocker use, and being African American compared with being Caucasian were associated with a lower peak exercise capacity for both sexes. Hypertension and use of diabetes medications were associated with lower peak exercise capacity in women. CONCLUSIONS: Individuals with diabetes who are overweight or obese have impaired exercise capacity, which is primarily related to age, female sex, and race, as well as poor metabolic control, BMI, and central obesity.

Jakicic JM, Gallagher KI. · Physical Activity and Weight Management Research Center, University of Pittsburgh, PA 15261, USA. · Exerc Sport Sci Rev. · Pubmed #12715973 No free full text.

Abstract: The significant rise in the prevalence of overweight and obesity has increased the importance of addressing this significant public health problem. Exercise appears to be an important factor for addressing the obesity epidemic. This review will focus on the role of exercise in the management of body weight and factors that should be considered when prescribing exercise to overweight adults.

Jakicic JM, Wing RR, Winters-Hart C. · Brown Medical School/The Miriam Hospital, Providence, RI, USA. · Med Sci Sports Exerc. · Pubmed #12370568 No free full text.

Abstract: PURPOSE: To examine whether change in physical activity is associated with compliance to changes in dietary intake and eating behaviors in an 18-month behavioral weight loss program, and to examine the contribution of exercise to weight loss when these other weight loss behaviors are also considered. METHODS: Data from 104 subjects who completed an 18-month behavioral weight loss program were analyzed in this study. All subjects were prescribed a reduced energy (1,200-1,500 kcal x d(-1)) and fat (20 to 30%) diet, and exercise progressed from 100 to 200 min x wk(-1). Subjects attended group behavioral lessons throughout the study. Weight, physical activity, energy intake, and weight loss eating behaviors were assessed at 0 and 18 months. RESULTS: Body weight decreased 7.8 +/- 7.5 kg and body mass index decreased 2.8 +/- 2.7 kg x m(-2) from 0 to 18 months ( < 0.05). Total energy intake (kcal x d(-1)) and macronutrient intake (g x d(-1)) decreased, whereas physical activity and eating behaviors associated with weight loss increased from 0 to 18 months ( < 0.05). Change in physical activity was significantly correlated with weight loss (r = 0.33), reductions in energy intake (r = 0.20), and improvements in eating behaviors associated with weight loss (r = 0.24) ( < 0.05). Regression analysis indicated that change in physical activity significantly improved weight loss after changes in energy intake and weight loss eating behaviors were considered in the analysis, with R(2)significantly improving by approximately 0.04 ( < 0.05). However, results from multiple regression showed weight loss was influence more by changes in eating behaviors than changes in physical activity (R(2) = 0.17 vs R(2) = 0.04). CONCLUSIONS: The combination of changes in eating and physical activity behaviors can improve long-term weight loss compared with either behavior alone. Interventions targeting both behaviors are recommended for improving long-term weight loss.

Gallagher KI, Jakicic JM, Kiel DP, Page ML, Ferguson ES, Marcus BH. · Weight Control and Diabetes Research Center and Center for Behavioral and Preventive Medicine, The Miriam and Brown Medical School, Providence, Rhode Island, USA. · Obes Res. · Pubmed #12226138 No free full text.

Abstract: OBJECTIVE: The purpose of this study was to examine the effect of weight cycling (as defined by the frequency and magnitude of intentional weight loss) on bone mineral density and bone mineral content in obese sedentary women. RESEARCH METHODS AND PROCEDURES: Bone mineral content and density measured by DXA, submaximal physical fitness assessment, nutrient intake, oral contraceptive use, and weight-cycling history were assessed in 195 healthy, overweight sedentary women (age, 21 to 45 years; body mass index, 27 to 40 kg/m(2)) before beginning a behavioral weight-loss intervention. RESULTS: After controlling for body weight, multivitamin use, oral contraceptive/estrogen use, and calcium and magnesium intake, women who had a history of weight cycling did not have significantly lower total-body bone mineral content or density or total femur bone mineral density. In addition, 99% of subjects were above or within one SD of age and gender normative data for total femur bone mineral density. DISCUSSION: It does not seem that a history of weight cycling has an adverse affect on total femur and total-body bone mineral density in overweight sedentary premenopausal women.

Jakicic JM, Lang W, Wing RR. · Brown University School of Medicine, Miriam Hospital, Weight Control and Diabetes Research Center, Providence, Rhode Island 02906, USA. · Int J Obes Relat Metab Disord. · Pubmed #11443491 links to  free full text

Abstract: OBJECTIVE: To examine whether there are ethnic differences in oxygen consumption during fixed periods of exercise. DESIGN: Cross-sectional. SUBJECTS: Twenty-seven African-American and 120 Caucasian overweight adult women (body mass index=32.8+/-4.1 kg/m(2), age=36.7+/-5.6 y) prior to initiating a weight loss program. MEASUREMENTS: Measurement of oxygen consumption occurred during four stages of a graded exercise test, with body composition assessed by dual-energy X-ray absorptiometry. RESULTS: There were no significant differences between overweight African-American and Caucasian women for absolute oxygen consumption or oxygen consumption adjusted for either body weight or fat-free mass across four levels of a submaximal graded exercise test. CONCLUSION: The results from this study suggest that African-American and Caucasian women do not differ in energy expenditure during fixed workloads of exercise, suggesting that this may not contribute to differences in energy balance and body weight regulation between women in these two ethnic groups.

Jakicic JM, Winters C, Lagally K, Ho J, Robertson RJ, Wing RR. · Obesity/Nutrition Research Center and Human Energy Research Laboratory, University of Pittsburgh, School of Medicine, PA 15213, USA. · Med Sci Sports Exerc. · Pubmed #10331898 No free full text.

Abstract: PURPOSE: This study examined the reliability and validity of the TriTrac-R3D triaxial accelerometer to estimate energy expenditure during various modes of exercise. METHODS: Twenty subjects (age = 21.5+/-3.4 yr; body mass index = 23.3+/-3.6 kg x m(-2)) performed five exercises (treadmill walking, treadmill running, stepping, stationary cycling, and slideboard), with each lasting 20-30 min and workload increased at 10-min intervals. To test the inter-TriTrac reliability, two TriTrac-R3D accelerometers were worn during each exercise period, and to examine validity, a simultaneous measurement of energy expenditure was made using indirect calorimetry (SensorMedics 2900 Metabolic Cart). RESULTS: Results showed a significant correlation between the two TriTrac-R3D accelerometers during all exercises. The difference in estimated energy expenditure between the two accelerometers during the walking, stepping, and slideboard exercises was less than 1 kcal x min(-1) but statistically significant (P<0.05). There was also a significant correlation between energy expenditure estimated by each of the TriTrac-R3D accelerometers and indirect calorimetry during walking, running, stepping, and slideboard exercise (P<0.05). The interaction of Method x Workload was significant (P<0.05) for each exercise, indicating that the TriTrac-R3D underestimates energy expenditure and that the magnitude of this underestimation increases as workload increases. CONCLUSIONS: Therefore, energy expenditure estimated via triaxial accelerometry does not increase with increasing workloads. These results suggest that there are limitations to using triaxial accelerometry to quantify energy expenditure.

Jakicic JM. · Physical Activity and Weight Management Research Center, University of Pittsburgh, PA 15261, USA. · J Nutr. · Pubmed #12468633 links to  free full text

Abstract: Overweight and obesity are increasing in prevalence, and this has resulted in a significant public health burden. Therefore, it is important to identify interventions that prevent weight gain and prevent weight regain after weight loss. Energy expended in physical activity has the potential to affect energy balance, and this can potentially affect body weight regulation. There is some evidence that physical activity can minimize weight gain, and it appears that needs to be moderate to vigorous in intensity to significantly affect body weight. Moreover, it appears that improvements in fitness are associated with reductions in risk of weight gain. Physical activity also is associated with improved maintenance of weight loss. Although it appears that interventions targeting physical activity are necessary to affect weight gain and improve long-term weight loss, the impact of these interventions on other components of energy balance should be examined. In addition, although minimal public health recommendations can significantly affect health outcomes, additional research is needed to identify the optimal dose of physical activity to prevent weight gain and improve long-term weight loss.