Physical activity in free-living, overweight white and black women: divergent responses by race to diet-induced weight loss

Changes in Trunk, but Not Limb, Lean Body Mass Contribute to Variability in Metabolic Adaptation Following Weight Loss

Background

Metabolic adaptation (MA) in response to weight loss is highly variable. Several methodological issues are likely to contribute to the large inter-individual variability in MA, namely the lack of adjustment for changes in the composition of fat-free mass.

Objective

The aim of this analysis was to investigate the contribution of changes in trunk versus limb lean body mass (LBM) to the variability in MA, at the level of resting metabolic rate (RMR).

Methods

116 premenopausal women with overweight (body mass index (BMI): 28.2 ± 1.2 kg/m2; age: 34.4 ± 6.4 years) enrolled in a weight loss program. Body weight/composition (dual energy x-ray absorptiometry), RMR (indirect calorimetry) and insulin sensitivity (SI) (intravenous glucose tolerance test) were measured after 4 weeks of weight stability at baseline and after weight loss. Multiple linear regression was used to determine the contribution of changes in trunk versus limb LBM to MA variability, after adjusting for relevant confounders.

Results

A large variation in MA (-206 to +233 kcal/day) was found after an average of 12.1 ± 2.4 kg weight loss. After adjusting for RMR at baseline and changes in SI, changes in trunk (but not limb) LBM were a significant contributor to MA variability.

Conclusion

In premenopausal women with overweight and loss of trunk, but not limbs, LBM contributes to MA variability, suggesting that loss of organ mass might be more important than loss of skeletal mass in modulating the magnitude of MA. Trial Registration: ClinicalTrial.gov Identifier (JULIET study): NCT00067873, URL: https://clinicaltrials.gov/ct2/show/NCT0006787.

Weight loss maintenance after bariatric surgery

Metabolic and bariatric surgery (MBS) is an effective treatment for patients with morbid obesity and its comorbidities. However, many patients experience weight regain (WR) after achieving their nadir weight. Establishing the definition of WR is challenging as postoperative WR has various definitions. Risk factors for WR after MBS include anatomical, racial, hormonal, metabolic, behavioral, and psychological factors, and evaluating such factors preoperatively is necessary. Long-term regular follow-up and timely treatment by a multidisciplinary team are important because WR after surgery is multi-factorial. Although lifestyle interventions that focus on appropriate dietary education, physical activity education or interventions, and behavioral psychological interventions are suggested, more well-designed studies are needed because studies evaluating intervention methods and the effectiveness of WR prevention are lacking. Anti-obesity drugs can be used to prevent and manage patients with WR after MBS; however, more research is needed to determine the timing, duration, and type of anti-obesity drugs used to prevent WR.

Factors influencing bariatric surgery outcomes

The outcomes of bariatric surgery, while often impressive, are not universally satisfactory; they vary from patient to patient and from operation to operation. Between 20-30% of patients experience suboptimal weight loss or substantial weight regain early in their postoperative course. Confronted with this chronic disease, and given that failures are difficult to manage, it is essential to better characterize obesity preoperatively, considering other metrics beyond just the body mass index (BMI), to select the best candidates for surgery and optimize the benefit/risk ratio. Based on the data of the most recent studies on bariatric surgery, our objective is to identify the predictive factors of weight loss as well as the risk factors of failure. Our analysis indicates that the choice of the surgical technique, age, initial BMI, ethnic origin, the presence of eating disorders and metabolic factors all have an impact on weight-loss outcomes after bariatric surgery. Thus, it is of major importance to carefully select patients during a preoperative multidisciplinary discussion in order to optimize weight loss and metabolic outcomes.

Metabolic adaptation is an illusion, only present when participants are in negative energy balance

BACKGROUND

The existence of metabolic adaptation, following weight loss, remains a controversial issue. To our knowledge, no study has evaluated the role of energy balance (EB) in modulating metabolic adaptation.

OBJECTIVES

The aim of this study was to determine if metabolic adaptation, at the level of resting metabolic rate (RMR), is modulated by participants' EB status. A secondary aim was to investigate if metabolic adaptation was associated with weight regain.

METHODS

Seventy-one individuals with obesity (BMI: 34.6 ± 3.4 kg/m2; age: 45.4 ± 8.2 y; 33 men) enrolled in a 1000-kcal/d diet for 8 wk, followed by 4 wk of weight stabilization and a 9-mo weight loss maintenance program. Body weight/composition and RMR were measured at baseline, week 9 (W9), week 13 (W13), and 1 y (1Y). Metabolic adaptation was defined as a significantly different (lower or higher) measured compared with predicted RMR.

RESULTS

Participants lost on average 14 kg by W9, followed by weight stabilization at W13, and regained 29% of their initial weight loss at 1Y. Metabolic adaptation was found at W9 (-92 ± 110 kcal/d, P < 0.001) and W13 (-38 ± 124 kcal/d, P = 0.011) but was not correlated with weight regain. A significant reduction in metabolic adaptation was seen between W9 and W13 (-53 ± 101 kcal/d, P < 0.001). In a subset of participants who gained weight between W9 and W13 (n = 33), no metabolic adaptation was seen at W13 (-26.8 ± 121.5 kcal/d, P = 0.214). In a subset of participants with data at all time points (n = 45), metabolic adaptation was present at W9 and W13 (-107 ± 102 kcal/d, P < 0.001 and -49 ± 128 kcal/d, P = 0.013) but not at 1Y (-7 ± 129, P = 0.701).

CONCLUSION

After weight loss, metabolic adaptation at the level of RMR is dependent on the EB status of the participants, being reduced to half after a period of weight stabilization. Moreover, metabolic adaptation does not predict weight regain at 1Y follow-up. These trials were registered at clinicaltrials.gov as NCT02944253 and NCT03287726.

Revisiting the Compensatory Theory as an explanatory model for relapse in obesity management

Weight regain remains the main challenge in obesity management, and its etiology remains elusive. The aim of the present review was to revise the available evidence regarding the "Compensatory Theory," which is an explanatory model of relapse in obesity treatment, and to propose alternative mechanisms that can contribute to weight regain. It has been proposed, and generally accepted as true, that when a person loses weight the body fights back, with physiological adaptations on both sides of the energy balance equation that try to bring body weight back to its original state: this is the Compensatory Theory. This theory proposes that the increased orexigenic drive to eat and the reduced energy expenditure that follow weight loss are the main drivers of relapse. However, evidence showing a link between these physiological adaptations to weight loss and weight regain is lacking. Here, we propose that the physiological adaptations to weight loss, both at the level of the homeostatic appetite control system and energy expenditure, are in fact a normalization to a lower body weight and not drivers of weight regain. In light of this we explore other potential mechanisms, both physiological and behavioral, that can contribute to the high incidence of relapse in obesity management. More research is needed to clearly ascertain whether the changes in energy expenditure and homeostatic appetite markers seen in reduced-obese individuals are a compensatory mechanism that drives relapse or a normalization towards a lower body weight, and to explore alternative hypotheses that explain relapse in obesity management.

Metabolic adaptation is not a major barrier to weight-loss maintenance

BACKGROUND

The existence of metabolic adaptation, at the level of resting metabolic rate (RMR), remains highly controversial, likely due to lack of standardization of participants' energy balance. Moreover, its role as a driver of relapse remains unproven.

OBJECTIVE

The main aim was to determine if metabolic adaptation at the level of RMR was present after weight loss and at 1- and 2-y follow-up, with measurements taken under condition of weight stability. A secondary aim was to investigate race differences in metabolic adaptation after weight loss and if this phenomenon was associated with weight regain.

METHODS

A total of 171 overweight women [BMI (kg/m2): 28.3 ± 1.3; age: 35.2 ± 6.3 y; 88 whites and 83 blacks] enrolled in a weight-loss program to achieve a BMI <25, and were followed for 2 y. Body weight and composition (4-compartment model) and RMR (indirect calorimetry) were measured after 4 wk of weight stability at baseline, after weight loss and at 1 and 2 y. Metabolic adaptation was defined as a significantly lower measured compared with predicted RMR (from own regression model).

RESULTS

Participants lost, on average, 12 ± 2.6 kg and regained 52% ± 38% and 89% ± 54% of their initial weight lost at 1 and 2 y follow-up, respectively. Metabolic adaptation was found after weight loss (-54 ± 105 kcal/d; P < 0.001), with no difference between races and was positively correlated with fat-mass loss, but not with weight regain, overall. In a subset of women (n = 46) with data at all time points, metabolic adaptation was present after weight loss, but not at 1- or 2-y follow-up (-43 ± 119, P = 0.019; -18 ± 134, P = 0.380; and - 19 ± 166, P = 0.438 kcal/day respectively).

CONCLUSIONS

In overweight women, metabolic adaptation at the level of RMR is minimal when measurements are taken under conditions of weight stability and does not predict weight regain up to 2 years follow-up.The JULIET study is registered at https://clinicaltrials.gov/ct2/show/NCT00067873 as NCT00067873.

Association of Race With Bariatric Surgery Outcomes

Importance

The outcomes of bariatric surgery vary considerably across patients, but the association of race with these measures remains unclear.

Objective

To examine the association of race on perioperative and 1-year outcomes of bariatric surgery.

Design, Setting, and Participants

Propensity score matching was used to assemble cohorts of black and white patients from the Michigan Bariatric Surgery Collaborative who underwent a primary bariatric operation (Roux-en-Y gastric bypass, sleeve gastrectomy, or adjustable gastric banding) between June 2006 and January 2017. Cohorts were balanced on baseline characteristics and procedure. Conditional fixed-effects models were used to evaluate the association of race on outcomes within hospitals and surgeons. Data analysis occurred from June 2006 through August 2018.

Main Outcomes and Measures

Thirty-day complications and health care resource utilization measures, as well as 1-year weight loss, comorbidity remission, quality of life, and satisfaction.

Results

In each group, 7105 patients were included. Black patients had a higher rate of any complication (628 [8.8%] vs 481 [6.8%]; adjusted odds ratio, 1.33 [95% CI, 1.17-1.51]; P = .02), but there were no significant differences in the rates of serious complications (178 [2.5%] vs 135 [1.9%]; adjusted odds ratio, 1.32 [95% CI, 1.05-1.66]; P = .29) or mortality (5 [0.10%] vs 7 [0.10%]; adjusted odds ratio, 0.73 [95% CI, 0.23-2.31]; P = .54). Black patients had a greater length of stay (mean [SD], 2.2 [3.0] days vs 1.9 [1.7] days; adjusted odds ratio, 0.30 [95% CI, 0.20-0.40]; P < .001), as well as a higher rate of emergency department visits (541 [11.6%] vs 826 [7.6%]; adjusted odds ratio, 1.60 [95% CI, 1.43-1.79]; P < .001) and readmissions (414 [5.8%] vs 245 [3.5%]; adjusted odds ratio, 1.73 [95% CI, 1.47-2.03]; P < .001). At 1 year, black patients had lower mean total body weight loss and as a percentage of weight (32.0 kg [26%]; vs 38.3 kg [29%]; P < .001) and this held true across procedures. Remission of hypertension was lower for black patients (564 [40.0%] vs 1096 [56.0%]; P < .001), but the rate of sleep apnea remission (467 [62.6%] vs 615 [56.1%]; P = .005) and gastroesophageal reflux disease (309 [78.6%] vs 453 [75.4%]; P = .049) were higher. There were no significant differences in remission of diabetes with insulin dependence, diabetes without insulin dependence,or hyperlipidemia hyperlipidemia. Fewer black patients than white patients reported a good or very good quality of life (1379 [87.2%] vs 2133 [90.4%]; P = .002) and being very satisfied with surgery (1908 [78.4%] vs 2895 [84.2%]; P < .001) at 1 year.

Conclusions and Relevance

Black patients undergoing bariatric surgery in Michigan had significantly higher rates of 30-day complications and resource utilization and experienced lower weight loss at 1 year than a matched cohort of white patients. While sleep apnea and gastroesophageal reflux disease remission were higher and hypertension remission lower in black patients, comorbidity remission was otherwise similar between matched cohorts. Racial and cultural differences among patients should be considered when designing strategies to optimize outcomes with bariatric surgery.

High-intensity interval training and calorie restriction promote remodeling of glucose and lipid metabolism in diet-induced obesity

Calorie restriction (CR) decreases adiposity, but the magnitude and defense of weight loss is less than predicted due to reductions in total daily energy expenditure (TEE). The purpose of the current investigation was to determine whether high-intensity interval training (HIIT) would increase markers of sympathetic activation in white adipose tissue (WAT) and rescue CR-mediated reductions in EE to a greater extent than moderate-intensity aerobic exercise training (MIT). Thirty-two 5-wk-old male C57BL/6J mice were placed on ad libitum HFD for 11 wk, followed by randomization to one of four groups (n = 8/group) for an additional 15 wk: 1) CON (remain on HFD), 2) CR (25% lower energy intake), 3) CR + HIIT (25% energy deficit created by 12.5% CR and 12.5% EE through HIIT), and 4) CR + MIT (25% energy deficit created by 12.5% CR and 12.5% EE through MIT). Markers of adipose thermogenesis (Ucp1, Prdm16, Dio2, and Fgf21) were unchanged in either exercise group in inguinal or epididymal WAT, whereas CR + HIIT decreased Ucp1 expression in retroperitoneal WAT and brown adipose tissue. HIIT rescued CR-mediated reductions in lean body mass (LBM) and resting energy expenditure (REE), and both were associated with improvements in glucose/insulin tolerance. Improvements in glucose metabolism in the CR + HIIT group appear to be linked to a molecular signature that enhances glucose and lipid storage in skeletal muscle. Exercise performed at either moderate or high intensity does not increase markers of adipose thermogenesis when performed in the presence of CR but remodels skeletal muscle metabolic and thermogenic capacity.

Exercise training improves fat metabolism independent of total energy expenditure in sedentary overweight men, but does not restore lean metabolic phenotype

BACKGROUND

Obesity is a dietary fat storage disease. Although exercise prevents weight gain, effects of chronic training on dietary fat oxidation remains understudied in overweight adults.

OBJECTIVE

We tested whether 2 months of training at current guidelines increase dietary fat oxidation in sedentary overweight adults like in sedentary lean adults.

DESIGN

Sedentary lean (n=10) and overweight (n=9) men trained on a cycle ergometer at 50% VO_2peak, 1 h day^-1, four times per week, for 2 months while energy balance was clamped. Metabolic fate of [d₃₁]palmitate and [1-¹³C]oleate mixed in standard meals, total substrate use, total energy expenditure (TEE), activity energy expenditure (AEE) and key muscle proteins/enzymes were measured before and at the end of the intervention.

RESULTS

Conversely to lean subjects, TEE and AEE did not increase in overweight participants due to a spontaneous decrease in non-training AEE. Despite this compensatory behavior, aerobic fitness, insulin sensitivity and fat oxidation were improved by exercise training. The latter was not explained by changes in dietary fat trafficking but more likely by a coordinated response at the muscle level enhancing fat uptake, acylation and oxidation (FABPpm, CD36, FATP1, ACSL1, CPT1, mtGPAT). ACSL1 fold change positively correlated with total fasting (R²=0.59, P<0.0001) and post-prandial (R²=0.49, P=0.0006) fat oxidation whereas mtGPAT fold change negatively correlated with dietary palmitate oxidation (R²=0.40, P=0.009), suggesting modified fat trafficking between oxidation and storage within the muscle. However, for most of the measured parameters the post-training values observed in overweight adults remained lower than the pre-training values observed in the lean subjects.

CONCLUSION

Independent of energy balance and TEE, exercise training at current recommendations improved fitness and fat oxidation in overweight adults. However the improved metabolic phenotype of overweight adults was not as healthy as the one of their lean counterparts before the 2-month training, likely due to the spontaneous reduction in non-training AEE.

Disparities in Treatment Uptake and Outcomes of Patients with Obesity in the USA

There are clear and persistent disparities in obesity prevalence within the USA. Some of these disparities fall along racial/ethnic lines; however, there are a number of other social and demographic constructs where obesity disparities are present. In addition to differing rates of obesity across groups, there is growing evidence that subgroups of patients both seek out and respond to obesity treatment differently. This review article explores the epidemiology of obesity disparities, as well as the existing evidence around how different groups may respond to behavioral, medical, and surgical therapies, and potential reasons for differential uptake and response, from culture, to access, to physiology. We find that the vast majority of evidence in this area has focused on the observation that African Americans tend to lose less weight in clinical trials compared to non-Hispanic whites and mainly pertains to behavioral interventions. Moving forward, there will be a need for studies that broaden the notion of health disparity beyond just comparing African Americans and non-Hispanic whites. Additionally, a more thorough examination of the potential for disparate outcomes after medical and surgical treatments of obesity is needed, coupled with the careful study of possible physiologic drivers of differential treatment response.

Exercise Training and Energy Expenditure following Weight Loss

PURPOSE

This study aims to determine the effects of aerobic or resistance training on activity-related energy expenditure (AEE; kcal·d(-1)) and physical activity index (activity-related time equivalent (ARTE)) following weight loss. It was hypothesized that weight loss without exercise training would be accompanied by decreases in AEE, ARTE, and nontraining physical activity energy expenditure (nonexercise activity thermogenesis (NEAT)) and that exercise training would prevent decreases in free-living energy expenditure.

METHODS

One hundred forty premenopausal women had an average weight loss of 25 lb during a diet (800 kcal·d(-1)) of furnished food. One group aerobically trained 3 times per week (40 min·d(-1)), another group resistance-trained 3 times per week (10 exercises/2 sets × 10 repetitions), and the third group did not exercise. Dual-energy x-ray absorptiometry was used to measure body composition, indirect calorimetry was used to measure resting energy expenditure (REE) and walking energy expenditure, and doubly labeled water was used to measure total energy expenditure (TEE). AEE, ARTE, and nontraining physical activity energy expenditure (NEAT) were calculated.

RESULTS

TEE, REE, and NEAT all decreased following weight loss for the no-exercise group, but not for aerobic and resistance trainers. Only REE decreased in the two exercise groups. Resistance trainers increased ARTE. HR and oxygen uptake while walking on the flat and up a grade were consistently related to TEE, AEE, NEAT, and ARTE.

CONCLUSIONS

Exercise training prevents a decrease in energy expenditure, including free-living energy expenditure separate from exercise training, following weight loss. Resistance training increases physical activity, whereas economy/ease of walking is associated with increased TEE, AEE, NEAT, and ARTE.

Cardiorespiratory Fitness and Light-Intensity Physical Activity Are Independently Associated with Reduced Cardiovascular Disease Risk in Urban Black South African Women: A Cross-Sectional Study

BACKGROUND

Low levels of physical activity, poor cardiorespiratory fitness, and a sedentary lifestyle have been associated with increased risk for cardiovascular disease (CVD) and type 2 diabetes (T2D). Few studies have examined their independent associations in an urban black sub-Saharan African population.

OBJECTIVES

To examine the independent associations of physical activity, cardiorespiratory fitness, and sedentary time on body composition and cardiometabolic risk factors for CVD and T2D in black South African women.

MATERIALS AND METHODS

A subsample (n = 76; 18-45 years) was recruited, as part of a cross-sectional study. Accelerometry, cardiorespiratory fitness, body composition, insulin sensitivity, serum lipids, and blood pressure were measured.

RESULTS

Light- but not moderate- to vigorous intensity physical activity was inversely associated with trunk fat mass (r = -0.25, P = 0.03). Sedentary time was associated with triglyceride (TG) (r = 0.36, P = 0.01) and TG/HDL-C (r = 0.34, P = 0.04), and these relationships were independent of body fat. Cardiorespiratory fitness was inversely associated with body fat % (r = -0.34, P = 0.02), central fat mass (r = -0.31, P = 0.03), visceral adipose tissue (VAT, r = -0.47, P < 0.01), and insulin resistance (HOMA-IR; r = -0.41, P = 0.01). The association between cardiorespiratory fitness and HOMA-IR was independent of body fat and physical activity, but not VAT. Cardiorespiratory fitness was inversely associated with sedentary time (r = -0.31, P = 0.03), but not with any of the physical activity variables (P > 0.05).

CONCLUSION

Both physical activity and cardiorespiratory fitness were associated with reduced total and central fat mass, VAT, and reduced cardiometabolic risk for CVD and T2D. Longitudinal studies are required to confirm whether the promotion of increasing light physical activity, while reducing sedentary time and increasing cardiorespiratory fitness, reduces the risk for obesity, CVD and T2D.

Racial Differences in Weight Loss Among Adults in a Behavioral Weight Loss Intervention: Role of Diet and Physical Activity

BACKGROUND

African-Americans lose less weight during a behavioral intervention compared with Whites, which may be from differences in dietary intake or physical activity.

METHODS

Subjects (30% African American, 70% White; n = 346; 42.4 ± 9.0 yrs.; BMI = 33.0 ± 3.7 kg/m2) in an 18-month weight loss intervention were randomized to a standard behavioral (SBWI) or a stepped-care (STEP) intervention. Weight, dietary intake, self-report and objective physical activity, and fitness were assessed at 0, 6, 12, and 18 months.

RESULTS

Weight loss at 18 months was greater in Whites (-8.74 kg with 95% CI [-10.10, -7.35]) compared with African Americans (-5.62 kg with 95% CI [-7.86, -3.37]) (P = .03) in the SBWI group and the STEP group (White: -7.48 kg with 95% CI [-8.80, -6.17] vs. African American: -4.41kg with 95% CI [-6.41, -2.42]) (P = .01). Patterns of change in dietary intake were not different between groups. Objective physical activity (PA) changed over time (P < .0001) and was higher in Whites when compared with African Americans (P = .01).

CONCLUSIONS

Whites lost more weight (3.10 kg) than African American adults. Although there were no differences in dietary intake, Whites had higher levels of objective PA and fitness. Thus, the discrepancy in weight loss may be due to differences in PA rather than dietary intake. However, the precise role of these factors warrants further investigation.

The effect of a 3-month moderate-intensity physical activity program on body composition in overweight and obese African American college females

SUMMARY

This study evaluated body composition outcomes following a 3-month exercise program for overweight/obese Black women. BMI decreased over the 3-month study despite an observed increase in body fat. Enhancements in bone marrow density and muscle density were also observed. Results show promising yet hypothesis-generating findings to explore in future research.

INTRODUCTION

Few studies have evaluated the relationship between aerobic physical activity (PA) and body composition among young adult overweight/obese African American (AA) women.

PURPOSE

The current study evaluated the effect of a 3-month moderate-intensity aerobic physical activity intervention for overweight and obese young adult women on bone, lean, and fat mass.

METHODS

Participants (n = 15) were a randomly selected subset of AA female college students (M age = 21.7 years; M BMI = 33.3) enrolled in a larger PA promotion pilot study (n = 31). Study protocol required participants to engage in four 30-60-min moderate-intensity aerobic PA sessions each week. Whole body composition was measured by dual-energy X-ray absorptiometry (DXA), and peripheral quantitative computed tomography (pQCT) was used to assess additional quantitative and qualitative assessment of the radius.

RESULTS

BMI decreased over the duration of the study (P = .034), reflected by a marginal decrease in body weight (P = .057). However, unexpectedly, increases in adipose tissue measures were observed, including total body fat (P = .041), percent body fat (P = .044), trunk fat (P = .031), and percent trunk fat (P = .041). No changes in DXA-measured bone outcomes were observed (i.e., bone mineral density, P = .069; bone mineral content, P = .211). Results from the pQCT assessment showed that bone marrow density increased (P = .011), but cortical density remained stable (P = .211). A marginally significant increase in muscle density (P = .053) and no changes in muscle area (P = .776) were observed.

CONCLUSIONS

A 3-month moderate-intensity PA program was associated with several promising findings, including increased bone marrow and stabilization of body weight. However, the increase in adipose tissue and trend for decreased bone mineral density were unexpected and indicate the need for future studies with larger samples to further explore these outcomes.

Impact of energy restriction with or without resistance training on energy metabolism in overweight and obese postmenopausal women: a Montreal Ottawa New Emerging Team group study

OBJECTIVE

The present study measured the impact of adding resistance training to an energy-restricted diet on the components of energy expenditure in overweight or obese postmenopausal women.

METHODS

Participants (n = 137) were randomly divided into two groups: (1) a diet and resistance training (DRT) group and (2) a diet-only (DO) group. Women followed a 6-month energy-restricted diet consisting of 2,100 to 3,360 kJ less than daily needs. The DRT group also followed a resistance training program (three times a week). Resting energy expenditure (REE) was measured by indirect calorimetry. Total energy expenditure was measured with doubly labeled water. Body composition was measured by dual-energy x-ray absorptiometry.

RESULTS

Eighty nine women were included in the analyses for this study (DRT, n = 21; DO, n = 68). REE in both groups was significantly lower after the intervention (mean difference ± SD: DO, -0.26 ± 0.4 MJ d; DRT, -0.33 ± 0.4 MJ d; P ≤ 0.05). Relative REE, expressed per kilogram of lean body mass corrected for fat mass change, remained stable in both groups. Physical activity energy expenditure remained stable in both groups (mean difference ± SD: DO, 0.02 ± 1 MJ d, P = 0.91; DRT, -0.14 ± 1 MJ d, P = 0.64).

CONCLUSIONS

Adding resistance training to an energy-restricted diet does not significantly alter any compartment of energy expenditure. REE is lower owing to reduction in body composition compartments, but relative REE is not significantly altered.

AFestschriftfor Roland L. Weinsier: Nutrition Scientist, Educator, and Clinician1

Roland L. Weinsier, M.D., Dr.P.H., devoted himself to the fields of nutrition and obesity for more than 35 years. He contributed outstanding work related to the treatment of obesity through dietary and lifestyle change; metabolic/energetic influences on obesity, weight loss, and weight regain; body composition changes accompanying weight loss and regain; the health benefits and risks of weight loss; nutrition education for physicians; and nutrition support of sick patients. He served on the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) National Task Force on Prevention and Treatment of Obesity, as Chair of the University of Alabama at Birmingham's Department of Nutrition Sciences, and as Founder and Director of its NIDDK-funded Clinical Nutrition Research Center. He was a long-time and active member of NAASO, serving in the roles of Councilor, Publications Committee Chair, Continuing Medical Education Course Director, Public Relations Committee Chair, and Membership Committee Co-Chair, to name just a few. He was well respected as a staunch defender of NAASO's scientific integrity in these roles. Sadly, Roland Weinsier died on November 27, 2002. He will be missed and remembered by many as a revered and beloved teacher, mentor, healer, and scholar.

Physical activity and body mass perception

PURPOSE

To evaluate ethnic perceptual variations in body mass index (BMI) and accrued physical activity. Women (n = 204) from the eastern United States were stratified into the following ethnic groups: White women (WW; n = 97), Black women (BW n = 62) and Others (Hispanic and Asian women, n = 45). Participants completed questionnaires and physiologic variables were determined. BW had increased weight, BMI, waist circumference, and body fat percentage vs. WW (p < .05). Body mass was higher in BW vs. Others (p < .05). There were no differences for perception of BMI or body dissatisfaction. BW were the only group in which perception of BMI was lower than measured BMI. BW engaged in 50% less domestic and total physical activity than WW and Others. Physical activity was not correlated to perception of BMI.

CONCLUSION

Perception of BMI was similar across ethnic groups and not correlated to physical activity levels in young women.

Are the 2005 Dietary Guidelines for Americans Associated With reduced risk of type 2 diabetes and cardiometabolic risk factors? Twenty-year findings from the CARDIA study

OBJECTIVE

To examine the prospective association between accordance with the 2005 Dietary Guidelines for Americans (DGA) and subsequent diabetes incidence and changes in cardiometabolic risk factors.

RESEARCH DESIGN AND METHODS

The sample consisted of 4,381 black and white young adults examined repeatedly from 1985 to 2005. We used the 2005 Diet Quality Index (DQI) to rate participants' diets based on meeting key dietary recommendations conveyed by the 2005 DGA.

RESULTS

Overall, we found no association between DQI score and diabetes risk using Cox models adjusted for potential confounders. Higher DQI scores were associated with favorable changes in HDL cholesterol and blood pressure overall (P for trend < 0.05), but with increased insulin resistance among blacks (P for trend < 0.01).

CONCLUSIONS

Our findings highlight the need for evaluation of the DGA's effectiveness, particularly among ethnic minority populations. Clinicians should be aware that following the DGA might not lower diabetes risk.

Consistency of fat mass--fat-free mass relationship across ethnicity and sex groups

The model developed by Forbes (1987) of how body fat mass (FM) and fat-free mass (FFM) change during periods of weight loss or gain (Δ body weight (BW)) assumed that they change in relationship to a constant C = 10·4, where ΔFFM/ΔBW = 10·4/(10·4+FM). Forbes derived C based on aggregated, cross-sectional data from a small sample of women. The objective of the present study was to reanalyse the relationship described by Forbes and to explore whether this relationship is consistent across ethnicity and sex groups using cross-sectional data from a large sample of white and African-American men and women. Baseline data from white and African-American men and women aged 18-60 years, who participated in a clinical study at the Pennington Biomedical Research Center since 2001 and who underwent dual-energy X-ray absorptiometry scans, were available for analysis. To overcome differences in BMI distributions among the ethnicity-by-sex groups, a stratified random sample of participants was selected within each group such that numbers in each BMI category ( < 25, 25-29·9, 30-34·9, 35-39·9, 40+ kg/m2) were proportional to those within the group with the smallest sample size, yielding a sample of 1953 individuals. Linear regression models assessed the FM-FFM relationship across the four ethnicity-by-sex groups. The FM-FFM relationship varied little by ethnicity (P = 0·57) or by sex (P = 0·26). The constant describing the FM-FFM relationship was estimated to be 9·7 (95 % CI 9·0, 10·3). In conclusion, results from our large, biethnic sample of men and women found a FM-FFM relationship very close to that originally described by Forbes, absent of significant variability by ethnicity or sex.

Diet quality and weight gain among black and white young adults: the Coronary Artery Risk Development in Young Adults (CARDIA) Study (1985-2005)

BACKGROUND

Little is known about the long-term health consequences of following the 2005 Dietary Guidelines for Americans (DGA; Washington, DC: US Government Printing Office, 2005).

OBJECTIVE

The objective was to examine the longitudinal association between diets consistent with the 2005 DGA and subsequent weight gain.

DESIGN

We used data from the Coronary Artery Risk Development in Young Adults (CARDIA) Study, a cohort of black and white men and women aged 18-30 y at baseline who attended ≤7 examinations from 1985-1986 to 2005-2006 (n = 4913). We created a 100-point Diet Quality Index (2005 DQI) to rate participants' diets based on meeting the 2005 DGA key recommendations. Longitudinal models of weight gain were adjusted for physical activity, smoking, energy intake, age, education, sex, and initial body mass index (BMI) and included interaction terms of DQI by race and initial BMI (if statistically significant).

RESULTS

We found effect modification by race (likelihood ratio test, P < 0.03 in all models). The mean adjusted 20-y weight change was +19.4 kg for blacks and +11.2 kg for whites with high diet quality (DQI >70) and +17.8 for blacks and +13.9 for whites with a DQI <50 (P < 0.05). In race-specific Cox models (with interaction terms for DQI × initial BMI, P < 0.05), a 10-point increase in DQI score was associated with a 10% lower risk of gaining 10 kg in whites with an initial BMI (in kg/m(2)) <25 but with a 15% higher risk in blacks with baseline obesity (P < 0.001).

CONCLUSIONS

Our findings do not support the hypothesis that a diet consistent with the 2005 DGA benefits long-term weight maintenance in American young adults. Greater need for attention to obesity prevention in future DGAs is warranted.

Total daily energy expenditure in black and white, lean and obese South African women

BACKGROUND/OBJECTIVES

In South Africa (SA), the prevalence of obesity in women is 56%, with black women being most at risk (62%). Studies in the United States have demonstrated ethnic differences in resting (REE) and total daily energy expenditure (TDEE) between African American (AA) and their white counterparts. We investigated whether differences in EE exist in black and white SA women, explaining, in part, the ethnic obesity prevalence differences.

SUBJECTS/METHODS

We measured REE, TDEE and physical activity EE (PAEE) in lean (BMI <25 kg m(-2)) and obese (BMI >30 kg m(-2)) SA women (N=44, 30+/-6 year). REE, TDEE, PAEE and total awake EE were measured during a 21 h stay in a respiration chamber.

RESULTS

Black and white subjects within obese and lean groups were not significantly different for age, mass, BMI and % body fat. However, fat-free mass (kg FFM) was consistently lower in the black women (P<0.01) in both weight groups. After adjusting EE measurements for differences in FFM, REE was not significantly different for either body weight or ethnicity, although 24 h TDEE (kJ) was significantly greater in the obese women (P<0.01) and white women (P<0.05). Total awake non-PAEE was not significantly different for either groups, while total awake time was only significantly lower for the lean groups (P<0.01). Total PAEE (kJ min(-1)) was significantly lower in the lean (P<0.001) and black groups (P<0.01).

CONCLUSIONS

In this sample of matched, lean and obese, black and white SA women, differences in TDEE were largely explained by ethnic differences in PAEE, and were not as a result of ethnic differences in REE.

Systematic review of the use of financial incentives in treatments for obesity and overweight

Nine studies met the criteria for inclusion in this systematic review of randomized controlled trials of treatments for obesity and overweight involving the use of financial incentives, with reported follow-up of at least 1 year. All included trials were of behavioural obesity treatments. Justification of sample size and blinding procedure were not mentioned in any study. Attrition was well described in three studies and no study was analysed on an intention to treat basis. Participants were mostly women recruited through media advertisements. Mean age ranged from 35.7 to 52.8 years, and mean body mass index from 29.3 to 31.8 kg m(-2). Results from meta-analysis showed no significant effect of use of financial incentives on weight loss or maintenance at 12 months and 18 months. Further sub-analysis by mode of delivery and amount of incentives although also non-statistically significant were suggestive of very weak trends in favour of use of amounts greater than 1.2% personal disposable income, rewards for behaviour change rather than for weight, rewards based on group performance rather than for individual performance and rewards delivered by non-psychologists rather than delivered by psychologists.

Effect of a dietary-induced weight loss on liver enzymes in obese subjects

BACKGROUND

Weight loss was shown to be associated with improvements in liver enzymes and improvements of nonalcoholic fatty liver disease. However, some evidence also shows that liver enzymes may transiently increase immediately after a dietary-induced weight loss.

OBJECTIVE

The aim was to assess the outcome of liver enzymes after a low-calorie diet (LCD) as well as during a follow-up period and to identify predictors for potential changes in these liver enzymes.

DESIGN

In this post hoc analysis of an existing database, liver enzymes were assessed before and immediately after a highly standardized soy-based meal replacement LCD providing 800 kcal/d, as well as 32 and 60 wk after the end of the LCD.

RESULTS

Data emanating from 147 obese subjects (104 women and 43 men) without known hepatic disease were included in this study. The LCD led to a median weight loss of 12.1 kg (range: 7.7-27.6 kg). In men, a significant decrease in alanine aminotransferase (ALT) and aspartate aminotransferase (AST) was observed immediately after the LCD, whereas, in women, these enzymes increased significantly, although mildly; however, this increase was transient. Sex was the only identifiable predictor of these changes in liver enzymes.

CONCLUSIONS

This study showed that mild, transient increases in ALT and AST values can be observed immediately after an LCD in women, but not in men. These changes are probably of multifactorial origin and may be considered as benign as long as they remain transient.

Weight loss and health outcomes in African Americans and whites after gastric bypass surgery

OBJECTIVE

The objective was to describe differences in weight loss, dietary intake, and cardiovascular risk factors between white and African-American patients after gastric bypass (GBP).

RESEARCH METHODS AND PROCEDURES

This was a retrospective database review of a sample of 84 adult patients (24 African-American and 60 white women and men) between the ages of 33 and 53 years. All subjects had GBP surgery in 2001 at the Bariatric Surgery Program at Boston Medical Center in Boston, MA, and were followed for one year postoperatively. Patients were excluded if weight data were missing at baseline, 3 months, or 1 year after GBP. A total of 9 African Americans and 41 whites provided data at all 3 time-points and were included in the study. Differences in weight loss, diet, and cardiovascular risk factors were analyzed.

RESULTS

There were no differences in baseline characteristics between African Americans and whites. Mean weight loss for the entire sample was 36 +/- 9%, with a range of 8% to 54% relative to initial body weight. Whites lost more weight (39 +/- 8%) than African Americans (26 +/- 10%) (p < 0.05). Dietary parameters, as well as improvements in blood pressure and lipid profiles, were similar in the two racial groups.

DISCUSSION

Differences in weight loss between severely obese African Americans and whites undergoing open GBP are unlikely to be related to postoperative dietary practices. Our data are consistent with previous reports implicating metabolic differences between the two racial groups.

Peptide-YY levels after a fat load in black and white women

OBJECTIVE

To determine whether basal plasma peptide-YY (PYY) levels in overweight, middle-aged black women are different from those of white women of similar BMI and age and ascertain whether there is a difference between the two groups in plasma PYY levels in response to a liquid high fat load.

RESEARCH METHODS AND PROCEDURES

Using a commercial radioimmunoassay kit, the concentration of PYY was measured at baseline and at 2, 4, 6, and 8 hours after ingesting a fatty liquid meal (86.5% of the calories from fat) in 12 black and 12 white women who were matched for age and BMI.

RESULTS

PYY levels (picograms per milliliter) at baseline and at every other time-point of the test meal were significantly lower in the black than in the white group. In addition, the change in PYY concentration from baseline was lower in the black than in the white group only at 8 hours after the meal.

DISCUSSION

The lower baseline level and the blunted PYY response of the black women to the fat load indicated that this signal for appetite suppression was reduced, which, in turn, might contribute to the enhanced obesity of the black women.

IGF-I polymorphism is associated with lean mass, exercise economy, and exercise performance among premenopausal women

BACKGROUND

We undertook this study to investigate the association of a genetic polymorphism of the insulin-like growth factor, IGF-I(189), on body composition, exercise performance and exercise economy, after controlling for the independent effect of race as assessed by African genetic admixture (AFADM).

METHODS

A total of 114 premenopausal sedentary women were genotyped for IGF-I189, obtaining measures of fat mass, lean body mass, VO2 during cycling and stairclimbing, time on treadmill and leg strength. A quantitative value for AFADM was derived from genotypic information of approximately 40 ancestry informative markers and used as covariate in statistical models.

RESULTS

After adjusting for AFADM, IGF-I189 was negatively associated with lean body mass (p = 0.029) and lean leg mass (p = 0.050). Leg strength was not associated with the presence/absence of IGF-I189 (p = 0.380), but carriers of the allele demonstrated a longer time on the treadmill (p = 0.015) after adjusting for AFADM. There was also a negative relationship between oxygen uptake during cycling and presence of the IGF-I189 independent of AFADM (p = 0.010).

CONCLUSIONS

Independent of AFADM, individuals with IGF-I189 are more likely to have low leg lean mass and to perform better in activities requiring exercise economy and endurance performance.

Racial and ethnic differences in predictors of smoking cessation

Racial/ethnic differences in the determinants of smoking cessation could have important treatment implications. The current study examined racial/ethnic differences in smoking cessation, prospective predictors of cessation, and whether the predictive ability of these factors differed by race/ethnicity. Participants were 709 employed adults recruited through the National Rural Electric Co-op Association or through natural gas pipeline corporations. Data were collected in 1990 and 1994. Although race/ethnicity was not predictive of abstinence, Hispanic, African American, and White smokers displayed differential on tobacco-, alcohol-, and work-related variables. These racial/ethnic differences highlight the specific factors that should be considered when providing smoking cessation treatment to specific populations. Limitations are noted.

Comparison of self-reported with objectively assessed energy expenditure in black and white women before and after weight loss

BACKGROUND

Weight maintenance is less successful in black women than in white women after weight loss.

OBJECTIVE

We compared objectively assessed total energy expenditure (TEE) with estimates of energy expenditure (EE) from self-reported physical activity (PA) in overweight black and white women before and after weight loss. We also compared those values with values in never-overweight control subjects.

DESIGN

A total of 20 white and 21 black premenopausal women were evaluated while overweight and weight reduced; 20 white and 14 black control subjects (matched with women in the weight-reduced state) were evaluated once. Weight loss of >/=10 kg was achieved by energy restriction in the overweight subjects. The evaluations were as follows: body composition (dual-energy X-ray absorptiometry), free-living TEE (doubly labeled water), Tecumseh Occupational Activity Questionnaire, Minnesota Leisure Time PA Questionnaire, and Baecke Activity Questionnaire.

RESULTS

Questionnaire estimates of TEE were overestimated when compared with TEE (P < 0.001). Overweight women overestimated TEE 49% more than did never-overweight control subjects. After weight loss, white women reduced overestimation of EE 48% (P < 0.05), so that their overestimation of EE was not different from that of black and white control subjects. Black women overestimated to the same extent both before and after weight loss.

CONCLUSIONS

Premenopausal women overestimate PA estimates on questionnaires. Overestimation of PA in weight-reduced black women is greater than in weight-reduced white women and never-overweight black and white women.

Physical activity and resting metabolic rate

The direct effects of physical activity interventions on energy expenditure are relatively small when placed in the context of total daily energy demands. Hence, the suggestion has been made that exercise produces energetic benefits in other components of the daily energy budget, thus generating a net effect on energy balance much greater than the direct energy cost of the exercise alone. Resting metabolic rate (RMR) is the largest component of the daily energy budget in most human societies and, therefore, any increases in RMR in response to exercise interventions are potentially of great importance. Animal studies have generally shown that single exercise events and longer-term training produce increases in RMR. This effect is observed in longer-term interventions despite parallel decreases in body mass and fat mass. Flight is an exception, as both single flights and long-term flight training induce reductions in RMR. Studies in animals that measure the effect of voluntary exercise regimens on RMR are less commonly performed and do not show the same response as that to forced exercise. In particular, they indicate that exercise does not induce elevations in RMR. Many studies of human subjects indicate a short-term elevation in RMR in response to single exercise events (generally termed the excess post-exercise O2 consumption; EPOC). This EPOC appears to have two phases, one lasting < 2 h and a smaller much more prolonged effect lasting up to 48 h. Many studies have shown that long-term training increases RMR, but many other studies have failed to find such effects. Data concerning long-term effects of training are potentially confounded by some studies not leaving sufficient time after the last exercise bout for the termination of the long-term EPOC. Long-term effects of training include increases in RMR due to increases in lean muscle mass. Extreme interventions, however, may induce reductions in RMR, in spite of the increased lean tissue mass, similar to the changes observed in animals in response to flight.

How much physical activity is enough to prevent unhealthy weight gain? Outcome of the IASO 1st Stock Conference and consensus statement

A consensus meeting was held in Bangkok, 21-23 May 2002, where experts and young scientists in the field of physical activity, energy expenditure and body-weight regulation discussed the different aspects of physical activity in relation to the emerging problem of obesity worldwide. The following consensus statement was accepted unanimously. 'The current physical activity guideline for adults of 30 minutes of moderate intensity activity daily, preferably all days of the week, is of importance for limiting health risks for a number of chronic diseases including coronary heart disease and diabetes. However for preventing weight gain or regain this guideline is likely to be insufficient for many individuals in the current environment. There is compelling evidence that prevention of weight regain in formerly obese individuals requires 60-90 minutes of moderate intensity activity or lesser amounts of vigorous intensity activity. Although definitive data are lacking, it seems likely that moderate intensity activity of approximately 45 to 60 minutes per day, or 1.7 PAL (Physical Activity Level) is required to prevent the transition to overweight or obesity. For children, even more activity time is recommended. A good approach for many individuals to obtain the recommended level of physical activity is to reduce sedentary behaviour by incorporating more incidental and leisure-time activity into the daily routine. Political action is imperative to effect physical and social environmental changes to enable and encourage physical activity. Settings in which these environmental changes can be implemented include the urban and transportation infrastructure, schools, and workplaces.'