Ethnic and sex variations in overweight self-perception: relationship to sedentariness

Objective: With increasing frequency, health promotion messages advocating physical activity are claiming weight loss as a benefit. However, messages promoting physical activity as a weight loss strategy may have limited effectiveness and cross‐cultural relevance. We recently found self‐perceived overweight to be a more robust correlate of sedentary behavior than BMI in Los Angeles County adults. In this study, we examined ethnic and sex differences in overweight self‐perception and their association with sedentariness in this sample. Research Methods and Procedures: We conducted bivariate and multivariate analyses of cross‐sectional survey data from a representative sample of Los Angeles County adults. Results: Women were more likely to perceive themselves to be overweight than men overall (73.2% of overweight/non‐obese and 24.1% of average weight women vs. 44.5% of overweight/non‐obese and 5.6% of average weight men) and within each ethnic group. African‐Americans were least likely (41.3% of overweight/non‐obese African‐Americans self‐identified as overweight) and whites were most likely to consider themselves overweight (60.6% of overweight/non‐obese whites self‐identified as overweight). Overweight (vs. average weight) self‐perception was correlated with sedentariness among average weight adults (45.3% vs. 33.0%, p < 0.001), overweight adults (43.4% vs. 33.6%, p < 0.001), men (average and overweight: 38.4% vs. 27.8%, p < 0.001), overweight whites (41.9% vs. 29.7%, p = 0.0012), and African‐Americans and Latinos (41.6% vs. 33.9%, p = 0.005). Discussion: These data suggest that our society's emphasis on weight loss rather than lifestyle change may inadvertently discourage physical activity adoption/maintenance among non‐obese individuals. However, further research is needed, particularly from prospective cohort and intervention studies, to elucidate the relationship between overweight self‐perception and healthy lifestyle change.     

Comparison of Regional Fat Distribution and Health Risk Factors in Middle‐Aged White and African American Women: The Healthy Transitions Study

Objective: Both ethnicity and menopause appear to influence intra‐abdominal fat distribution. This study evaluated intra‐abdominal fat distribution and obesity‐related health risks in perimenopausal white and African American women. Research Methods and Procedures: Baseline data from a longitudinal study of changes in body composition and energy balance during menopause are reported. Healthy women (55 African Americans and 103 whites) who were on no medication and had at least five menstrual cycles in the previous 6 months were recruited. Body composition was assessed by DXA, and visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) were assessed by computed tomography scan. SAT was divided into deep and superficial layers demarcated by the fascia superficialis. Results: African American women were slightly younger (46.7 ± 0.2 vs. 47.7 ± 0.2 years, p = 0.002) and fatter (42.4% ± 1.0% vs. 39.4% ± 0.8% body fat, p = 0.02) than white women. In unadjusted data, African Americans had significantly more total abdominal fat and total, deep, and superficial SAT than whites. After adjustment for percent body fat and age, only total and superficial SAT remained significantly higher in African Americans. VAT although slightly less in African American women, did not differ significantly by race. In multiple regression analysis, VAT was the strongest predictor of serum lipids, glucose, and insulin in women of both races, although superficial SAT was significantly associated with fasting glucose in whites. Conclusions: Middle‐aged African American women have larger SAT depots, adjusted for total body fatness, but do not differ from white women with regard to VAT. The complexity of the relationship between abdominal fat and metabolic risk is increased by ethnic differences in such associations.     

Two-year internet-based randomized controlled trial for weight loss in African-American girls

Objective: A randomized controlled trial tested the efficacy of an internet‐based lifestyle behavior modification program for African‐American girls over a 2‐year period of intervention. Research Methods and Procedures: Fifty‐seven overweight (mean BMI percentile, 98.3) African‐American girls (mean age, 13.2 years) were randomly assigned to an interactive behavioral internet program or an internet health education program, the control condition. Overweight parents were also participants in the study. Forty adolescent‐parent dyads (70%) completed the 2‐year trial. Outcome data including BMI, body weight, body composition, and weight loss behaviors were collected at baseline and at 6‐month intervals. A computer server tracked use of the web sites. Results: An intention‐to‐treat statistical approach was used, with the last observation carried forward. In comparison with the control condition, adolescents in the behavioral program lost more mean body fat (BF) (?1.12 ± 0.47% vs. 0.43 ± 0.47% BF, p < 0.05), and parents in the behavioral program lost significantly more mean body weight (?2.43 ± 0.66 vs. ?0.35 ± 0.64 kg, p < 0.05) during the first 6 months. This weight loss was regained over the next 18 months. After 2 years, differences in fat for adolescents (?0.08 ± 0.71% vs. 0.84 ± 0.72% BF) and weight for parents (?1.1 ± 0.91 vs. ?0.60 ± 0.89 kg) did not differ between the behavioral and control programs. Discussion: An internet‐based weight management program for African‐American adolescent girls and their parents resulted in weight loss during the first 6 months but did not yield long‐term loss due to reduced use of the web site over time.     

Effect of group racial composition on weight loss in African Americans

Objective: We do not know how racial composition of a group influences behavior change for African Americans (AAs) in group‐based weight loss programs. We tested the hypothesis that AA who participate in all AA weight loss intervention groups will lose more weight than AA who participate in mixed race groups. Methods and Procedures: This observational study was ancillary to Phase 1 of the Weight Loss Maintenance Study, a multi‐center trial of strategies to maintain weight loss after a 20‐week behavior modification program. Three of four centers recruited several all‐AA intervention groups. Remaining groups were combinations of AA and non‐AA participants. All participants received the same weight loss intervention. Change in weight was the primary outcome, comparing participants of all‐AA groups with AA participants of mixed race groups conducted by the same AA interventionists. Secondary outcomes included measures of intervention adherence and behavior change. Results: Participants of all‐AA groups (n = 271) were comparable to other AA participants (n = 106). The mean proportion of AA in mixed race groups was 56%. All‐AA group participants had similar weight loss as those in mixed groups (?4.2 vs. ?4.2 kg, P = 0.97). There were no differences between the groups in mean number of sessions attended or changes in dietary intake. Discussion: Significant weight loss was observed in both groups, with no effect of group composition on adherence or weight loss outcomes. Special logistics to accommodate all‐AA groups may not be necessary. Despite varying instructional environments, AA appeared to respond positively to intervention messages with significant changes in dietary intake, physical activity (PA), and weight.     

Adiponectin and ghrelin levels and body size in normoglycemic Filipino, African-American, and white women

Objective: Prior studies have reported ethnic differences in adiponectin and ghrelin, but few have assessed the role of body size in normoglycemic women. We compared fasting adiponectin and ghrelin concentrations in normoglycemic 40‐ to 80‐year‐old Filipino, African‐American, and white women. Methods: Participants included women from the Rancho Bernardo Study (n = 143), the University of California‐San Diego Filipino Women's Health Study (n = 136), and the Health Assessment Study of African‐American Women (n = 212). A 2‐hour oral glucose tolerance test was administered; glucose, insulin, lipid, and anthropometric measurements were obtained. Fasting adiponectin and ghrelin were measured by radioimmunoassay. Results: Whites and Filipinas had similar BMI (23.7 and 24.3 kg/m², respectively), waist girth (75.6 and 77.2 cm, respectively), and total body fat (27.4 and 28.5%, respectively); African‐Americans had significantly larger BMI (28.8 kg/m²), waist girth (86.3 cm), and body fat (39.6%, p < 0.0001). Adiponectin was lower in Filipinas (8.90 µg/mL) and African‐Americans (9.67 µg/mL) compared with whites (15.6 µg/mL, p < 0.001) after adjusting for age, homeostasis model assessment of insulin resistance (HOMA‐IR), and waist‐to‐hip ratio. Compared with whites, Filipinas (β = ?5.06, p < 0.0001) and African‐Americans (β = ?6.85, p < 0.0001) had significantly lower adiponectin levels after adjusting for age, waist‐to‐hip ratio, HOMA‐IR, triglycerides, high‐density lipoprotein (HDL) cholesterol, exercise, and alcohol use. Ghrelin was significantly lower in Filipinas compared with African‐Americans (1146.9 vs. 1412.2 pg/mL, p < 0.001), and this observation persisted in multivariable analysis (β = ?245.4, p < 0.0001). Ghrelin levels did not differ between whites (1356.9 pg/mL) and either ethnic group. Discussion: Normoglycemic Filipino and African‐American women had significantly lower adiponectin concentrations than white women, and Filipinas had lower ghrelin levels than African‐Americans, independently of body size or indices of insulin resistance or lipids.     

Differences in Resting Metabolic Rate between White and African‐American Young Adults

Objective: A reported lower resting metabolic rate (RMR) in African‐American women than in white women could explain the higher prevalence of obesity in the former group. Little information is available on RMR in African‐American men. Research Methods and Procedures: We assessed RMR by indirect calorimetry and body composition by DXA in 395 adults ages 28 to 40 years (100 African‐American men, 95 white men, 94 African‐American women, and 106 white women), recruited from participants in the Coronary Artery Risk Development in Young Adults (CARDIA), Birmingham, Alabama, and Oakland, California, field centers. Results: Using linear models, fat‐free mass, fat mass, visceral fat, and age were significantly related to RMR, but the usual level of physical activity was not. After adjustment for these variables, mean RMR was significantly higher in whites (1665.07 ± 10.78 kcal/d) than in African Americans (1585.05 ± 11.02 kcal/d) by 80 ± 16 kcal/d (p < 0.0001). The ethnic × gender interaction was not significant (p = 0.9512), indicating that the difference in RMR between African‐American and white subjects was similar for men and women. Discussion: RMR is ～5% higher in white than in African‐American participants in CARDIA. The difference was the same for men and women and for lean and obese individuals. The prevalence of obesity is not higher in African‐American men than in white men. Because of these reasons, we believe that RMR differences are unlikely to be a primary explanation for why African‐American women are more prone to obesity than white women.     

Anti‐lipolytic Effects of Insulin in African American and White Prepubertal Boys

Objective: Relative to whites, African Americans have lower circulating triglycerides (TG) and greater highdensity lipoprotein cholesterol. The metabolic basis for this difference is not known. This study was conducted to test the hypothesis that insulin‐induced suppression of free fatty acids (FFA) results in lower serum TG in African American versus white prepubertal children. Research Methods and Procedures: Insulin, FFA, and TG were determined at baseline and during a frequently sampled, intravenous glucose tolerance test in eight African American and eight white prepubertal males pair‐matched for whole‐body insulin sensitivity. Results: Baseline TG was lower in African Americans (0.43 ± 0.10 vs. 0.79 ± 0.37 mM/L; mean ± SD; p < 0.01). African Americans had higher peak insulin (218 ± 102 vs. 100 ± 30 pM/L; mean ± SD; p < 0.01) and a greater acute insulin response (9282 ± 4272 vs. 4230 ± 1326 pM/L × 10 minutes; mean ± SD; p < 0.05). FFA and TG values determined at the FFA nadir were lower in African Americans (0.26 ± 0.02 vs. 0.30 ± 0.03 mEq/L; mean ± SD; p < 0.01 for FFA nadir and 0.49 ± 0.07 vs. 0.77 ± 0.33 mM/L; mean ± SD; p < 0.05 for TG). Among all subjects, FFA nadir was correlated with peak insulin (r = ?0.54; p < 0.05). After adjusting for FFA nadir, neither baseline nor postchallenge TG differed with ethnicity (p = 0.073 and 0.192, respectively). The ethnic difference in FFA nadir disappeared after adjusting for peak insulin (p = 0.073). Discussion: These data suggest that hyperinsulinemiainduced suppression of FFA among African Americans is a determinant of lower TG in this group.     

Serum Ghrelin Levels in Response to Glucose Load in Obese Subjects Post‐Gastric Bypass Surgery

Objective: We sought to elucidate further the mechanisms leading to weight loss after gastric bypass (GBP) surgery in morbidly obese individuals. Ghrelin is a gastroenteric appetite‐stimulating peptide hormone, fasting levels of which decrease with increasing adiposity and increase with diet‐induced weight loss. In addition, ghrelin levels rapidly decline postprandially. Research Methods and Procedures: We measured serum ghrelin responses to a 75‐g oral glucose tolerance test (OGTT) in 6 subjects who had undergone GBP surgery 1.5 ± 0.7 years before testing and compared these responses with 6 obese subjects about to undergo GBP surgery, 6 obese nonsurgical subjects (matched for BMI to the post‐GBP surgical group), and 5 lean subjects. Results: Despite weight loss induced by the GBP surgery, fasting serum ghrelin levels were significantly lower in the post‐GBP surgery group than in the lean subject (by 57%) or pre‐GBP surgery (by 45%) group. Serum ghrelin levels during the OGTT were significantly lower in postoperative than in lean, obese pre‐GBP surgical, or obese nonsurgical subjects. The magnitude of the decline in serum ghrelin levels between 0 and 120 minutes post‐OGTT was significantly smaller in postoperative (by 62%), obese pre‐GBP surgical (by 80%), or obese nonsurgical (by 69%) subjects in comparison with lean subjects. Discussion: Serum ghrelin levels in response to OGTT are lower in subjects post‐GBP surgery than in either lean or obese subjects. Tonically low serum ghrelin levels may be involved in the mechanisms inducing sustained weight loss after GBP surgery.     

Insulin Sensitivity in African‐American and White Women: Association With Inflammation

Whether the contribution of inflammation to risk for chronic metabolic disease differs with ethnicity is not known. The objective of this study was to determine: (i) whether ethnic differences exist in markers of inflammation and (ii) whether lower insulin sensitivity among African Americans vs. whites is due to greater inflammatory status. Subjects were African‐American (n = 108) and white (n = 105) women, BMI 27–30 kg/m². Insulin sensitivity was assessed with intravenous glucose tolerance test and minimal modeling; fat distribution with computed tomography; body composition with dual‐energy X‐ray absorptiometry; markers of inflammation (tumor necrosis factor (TNF)‐α, soluble tumor necrosis factor receptor (sTNFR)‐1, sTNFR‐2, C‐reactive protein (CRP), and interleukin (IL)‐6) with enzyme‐linked immunosorbent assay (ELISA). Whites had greater intra‐abdominal adipose tissue (IAAT), insulin sensitivity, and concentrations of TNF‐α, sTNFR‐1, and sTNFR‐2 than African Americans. Greater TNF‐α in whites vs. African Americans was attributed to greater IAAT in whites. Among whites, but not African Americans, CRP was independently and inversely associated with insulin sensitivity, after adjusting for IAAT (r = ?0.29 P < 0.05, and r = ?0.13 P = 0.53, respectively). Insulin sensitivity remained lower in African Americans after adjusting for CRP (P < 0.001). In conclusion, greater IAAT among whites may be associated with greater inflammation. Insulin sensitivity was lower among African Americans, independent of obesity, fat distribution, and inflammation.     

Higher post-absorptive skeletal muscle LPL activity in African American vs. non-Hispanic White pre-menopausal women

Objective: Higher post‐absorptive post‐heparin plasma lipoprotein lipase (LPL) activity has been reported in African Americans as compared to non‐Hispanic whites but differences in tissue‐specific LPL activity are unclear. Methods and Procedures: Post‐absorptive skeletal muscle (SM)‐LPL (vastus lateralis) and subcutaneous abdominal adipose tissue (AT)‐LPL activity was measured in overweight, sedentary African American females (n = 11) as well as in their non‐Hispanic white counterparts (n = 6) during a period of controlled low fat (30%) diet (for 10 days) combined with physical activity (for days 8–10). Post‐absorptive substrate utilization was measured on day 10; fasting blood levels and SM and AT biopsies were obtained on day 11. Results: African Americans had significantly greater post‐absorptive SM‐LPL activity (P = 0.04) when compared to non‐Hispanic whites. There were no significant differences in post‐absorptive AT‐LPL activity, free fatty acids, and systemic fat oxidation or respiratory quotient between African American and white non‐Hispanic women in this study (P > 0.2 for all). Discussion: During a controlled low fat (30%) diet post‐absorptive vastus lateralis SM‐LPL activity is higher in sedentary pre‐menopausal African American as compared to non‐Hispanic white women.     

Waist Circumference,BMI, and Visceral Adipose Tissue in White Women and Women of African Descent

Although waist circumference (WC) is a marker of visceral adipose tissue (VAT), WC cut‐points are based on BMI category. We compared WC‐BMI and WC‐VAT relationships in blacks and whites. Combining data from five studies, BMI and WC were measured in 1,409 premenopausal women (148 white South Africans, 607 African‐Americans, 186 black South Africans, 445 West Africans, 23 black Africans living in United States). In three of five studies, participants had VAT measured by computerized tomography (n = 456). Compared to whites, blacks had higher BMI (29.6 ± 7.6 (mean ± s.d.) vs. 27.6 ± 6.6 kg/m², P = 0.001), similar WC (92 ± 16 vs. 90 ± 15 cm, P = 0.27) and lower VAT (64 ± 42 vs. 101 ± 59 cm², P < 0.001). The WC‐BMI relationship did not differ by race (blacks: β (s.e.) WC = 0.42 (.01), whites: β (s.e.) WC = 0.40 (0.01), P = 0.73). The WC‐VAT relationship was different in blacks and whites (blacks: β (s.e.) WC = 1.38 (0.11), whites: β (s.e.) WC = 3.18 (0.21), P < 0.001). Whites had a greater increase in VAT per unit increase in WC. WC‐BMI and WC‐VAT relationships did not differ among black populations. As WC‐BMI relationship did not differ by race, the same BMI‐based WC guidelines may be appropriate for black and white women. However, if WC is defined by VAT, race‐specific WC thresholds are required.     

Endothelial function and weight loss: Comparison of low‐carbohydrate and low‐fat diets

Objective: The effect of weight loss on obesity‐associated endothelial dysfunction is not clear because of conflicting data, demonstrating both improvement and no change in endothelial function after weight loss in obese subjects. A 2‐year prospective study (n = 121) was conducted to examine: (1) the effect of obesity and weight loss (either a low‐carbohydrate or and low‐fat diet) on flow mediated vasodilatation (FMD), a measure of endothelial function. Design and Methods: Participants reduced body weight by 7.1% ± 4.4%, 8.7% ± 6.8%, 7.1% ± 7.8%, and 4.1% ± 7.7% at 3, 6, 12, and 24 months, respectively with no significant differences between the low‐fat and low‐carbohydrate groups. Results: Endothelial function was inversely correlated with waist circumference, triglyceride level, and directly correlated with leptin in obese persons prior to weight loss. These weight losses did not confer any improvements in FMD. There were no differences between the low‐fat and low‐carbohydrate diets in FMD at any time point. At 6 months (r = 0.26, P = 0.04) and 1 year (r =0.28, P = 0.03), there were positive correlations between change in FMD and change in leptin but not at 2 years. Conclusion: There was no significant improvement in endothelial function after 7.1% ± 7.8% weight loss at 1 year and 4.1% ± 7.7% at 2 years, achieved by either a low carbohydrate or a low fat diet.     

Obesity,End‐stage Renal Disease,and Survival in an Elderly Cohort With Cardiovascular Disease

Obesity is highly prevalent in African Americans and is associated with increased risk of End‐Stage Renal Disease (ESRD) and death. It is not known if the effect of obesity is similar among blacks and whites. The aim of this study is to examine racial differences in the association of obesity with ESRD and survival in elderly patients (age >65). Data were obtained for 74,167 Medicare patients with acute myocardial infarction (AMI) between February 1994 and July 1995. BMI was calculated as weight (kg) divided by height (m²). We evaluated the association of BMI class with ESRD incidence and death using multivariable Cox proportional hazards models, testing for race‐BMI interactions. Compared to whites, African Americans had higher BMI (26.9 vs. 26.0, P < 0.0001) and estimated glomerular filtration rate (72.4 ml/min/1.73 m² vs. 66.6 ml/min/1.73 m², P < 0.0001). Crude ESRD rates increased with increasing obesity among whites but not among blacks. However, after adjusting for age, sex, and other comorbidities, obesity was not associated with increased ESRD rate among blacks or whites and the interaction between race and BMI was not significant. Furthermore, for both races, patients classified as overweight, class 1 obese, or class 2 obese had similar, significantly better survival abilities compared to normal weight patients and the race BMI interaction was not significant. In conclusion, obesity does not increase risk of ESRD among black or white elderly subjects with cardiovascular disease (CVD). However, both obese blacks and whites, in this population, experience a survival benefit. Further studies need to explore this obesity paradox.     

Lower Serum Adiponectin Levels in African‐American Boys

Objective: To examine adiponectin, an adipocyte‐secreted hormone with anti‐inflammatory and insulin‐sensitizing effects, in relation to race or gender in younger subjects. Research Methods and Procedures: The relationship of adiponectin, quantitated by radioimmunoassay, to anthropometric and metabolic factors (fasting insulin, glucose, and leptin) and reproductive hormones was examined in 46 healthy African Americans (25 girls/21 boys) and 40 whites (20 girls/20 boys) ranging in age from 12 to 21 years. Results: There was no statistical difference in BMI or in BMI percentile among the four groups. Sums of skinfolds, but not skinfold percentile, were significantly lower in boys than girls (p = 0.001 and p = 0.896, respectively), whereas there was no difference between racial groups. Leptin was significantly greater in girls (p = 0.0002). There was no difference in fasting serum glucose, insulin, or homeostasis model assessment score among any of the groups. There was a significant negative univariate relationship between serum adiponectin and both BMI and BMI percentile for the entire group (p = 0.006 and p = 0.005). In a multivariate model, BMI percentile (p = 0.005) and the interaction between race and gender (p = 0.026) were significant predictors of serum adiponectin. In this model, African‐American boys had the lowest serum adiponectin level, 37% less than white boys, who had the highest adiponectin levels. Discussion: Serum adiponectin levels are reduced in young obese subjects (African Americans and whites) and are lower in African‐American boys than white boys. A lower adiponectin level in African‐American boys may predispose this group to a greater risk of diabetes and cardiovascular disease.     

Relationships of BMI to Cardiovascular Risk Factors Differ by Ethnicity

The burden of cardiovascular risk associated with obesity disproportionately affects African Americans and little is known about ethnic/racial differences in the relationship of obesity to cardiometabolic risk. This report assesses whether obesity is similarly associated with cardiometabolic risk factors in African Americans and whites of European ancestry. Cross‐sectional observational data from the Jackson Heart Study (JHS) and the Framingham Heart Study (FHS) were compared. This analysis uses participants aged 35–74 years with BMI >18.5 kg/m², and free of prevalent cardiovascular disease (CVD), from the initial JHS clinical examination (2000–2004) and the FHS Offspring (1998–2001) and Third Generation (2002–2005) cohorts. Participants were evaluated for the presence of lipid abnormalities, hypertension, and diabetes. Overall, 4,030 JHS (mean age 54 years, 64% women) and 5,245 FHS (mean age 51 years, 54% women) participants were available for analysis. The prevalence of all risk factors except high triglycerides and low high‐density lipoprotein (HDL) was substantially higher in JHS (all P < 0.001) and BMI was associated with increasing prevalence of most CVD risk factors within each race. For diabetes mellitus, hypertension, and low HDL, steeper relationships to BMI were observed in FHS than in JHS (P values <0.001–0.016). There were larger proportional increases in risk factor prevalence with increasing BMI in whites than in African Americans. The higher prevalence rates of cardiometabolic risk factors at nearly all levels of BMI in African Americans, however, suggest that additional factors contribute to the burden of CVD risk in African Americans.     

Visceral fat, waist circumference, and BMI: impact of race/ethnicity

Objective: BMI and waist circumference are used to define risk from excess body fat. Limited data in women suggest that there may be racial/ethnic differences in visceral adipose tissue (VAT) at a given BMI or waist circumference. This study tested the hypothesis that racial/ethnic differences exist in both men and women in the relationship of anthropometric measures of body composition and computed tomography (CT)‐determined VAT or subcutaneous adipose tissue (SAT). Methods and Procedures: Subjects included 66 African American, 72 Hispanic, and 47 white men and women, aged ≥ 45. Waist circumference and BMI were measured using standard methods. Total abdominal and L4L5 VAT and SAT were measured using CT. Results: Among both men and women, groups did not differ in waist circumference or BMI. White men had greater L4L5 VAT than African‐American men, and both white and Hispanic men had greater total VAT than African‐American men. Among women, Hispanics and whites had greater L4L5 VAT than African Americans, and Hispanics had greater total VAT than African Americans. The slope of the linear relationship between BMI or waist circumference and VAT was lower in African Americans than in Hispanics and/or whites. Discussion: Middle‐aged and older African‐American men and women had lower VAT despite similar BMI and waist circumference measurements. Altered relationships between anthropometric measures and VAT may have implications for defining metabolic risk in different populations. Different waist circumference or BMI cutoff points may be necessary to adequately reflect risk in different racial/ethnic groups.     

Three-year weight change in successful weight losers who lost weight on a low-carbohydrate diet

Objective: The purpose of this study was to evaluate long‐term weight loss and eating and exercise behaviors of successful weight losers who lost weight using a low‐carbohydrate diet. Research Methods and Procedures: This study examined 3‐year changes in weight, diet, and physical activity in 891 subjects (96 low‐carbohydrate dieters and 795 others) who enrolled in the National Weight Control Registry between 1998 and 2001 and reported ≥30‐lb weight loss and ≥1 year weight loss maintenance. Results: Only 10.8% of participants reported losing weight after a low‐carbohydrate diet. At entry into the study, low‐carbohydrate diet users reported consuming more kcal/d (mean ± SD, 1895 ± 452 vs. 1398 ± 574); fewer calories in weekly physical activity (1595 ± 2499 vs. 2542 ± 2301); more calories from fat (64.0 ± 7.9% vs. 30.9 ± 13.1%), saturated fat (23.8 ± 4.1 vs. 10.5 ± 5.2), monounsaturated fat (24.4 ± 3.7 vs. 11.0 ± 5.1), and polyunsaturated fat (8.6 ± 2.7 vs. 5.5 ± 2.9); and less dietary restraint (10.8 ± 2.9 vs. 14.9 ± 3.9) compared with other Registry members. These differences persisted over time. No differences in 3‐year weight regain were observed between low‐carbohydrate dieters and other Registry members in intent‐to‐treat analyses (7.0 ± 7.1 vs. 5.7 ± 8.7 kg). Discussion: It is possible to achieve and maintain long‐term weight loss using a low‐carbohydrate diet. The long‐term health effects of weight loss associated with a high‐fat diet and low activity level merits further investigation.     

Racial Differences in Insulin Secretion and Sensitivity in Prepubertal Children: Role of Physical Fitness and Physical Activity

Objective: To investigate in prepubertal children whether physical fitness and/or physical activity are: 1) associated with insulin secretion and sensitivity and 2) account for racial differences in insulin secretion and sensitivity. Research Methods and Procedures: Subjects included 34 African American and 34 white nondiabetic children aged 5 to 11 years. Data were divided into two sets according to the availability of VO_2max and physical activity data. Body composition was measured by dual‐energy X‐ray absorptiometry. Subcutaneous abdominal adipose tissue and intra‐abdominal adipose tissue were examined by computed tomography. Insulin sensitivity (S_I) and acute insulin response (AIR) were determined by a frequently sampled intravenous glucose tolerance test. An all‐out, progressive treadmill exercise test was used for measuring VO_2max. Physical activity data were collected by questionnaire. Results: African American children had lower S_I and higher AIR than white children, after adjusting for total body fat mass. African Americans reported higher levels of physical activity (hours/wk) than whites, but had a lower VO_2max. In multiple linear regression analysis, hours/wk of activity and hours/wk of vigorous activity, but not moderate activity, were independently related to S_I and AIR after adjusting for race, total body fat mass or fat distribution, and total lean tissue mass. VO_2max was not related to AIR, and was inversely related to S_I, after adjusting for body composition. Race remained significantly associated with both S_I and AIR, even after adjusting for body composition, fat distribution, and hours/wk of activity or hours/wk of vigorous activity. Discussion: In summary, overall physical activity and, especially, vigorous activity were associated with insulin secretion and sensitivity. However, neither physical activity nor VO_2max explained the racial difference in insulin secretion (higher in African Americans) and sensitivity (lower in African Americans). Thus, racial (African American to white) differences in aspects of insulin action seem to be due to factors other than body composition, fat distribution, cardiovascular fitness, and amount of physical activity.     

A pilot randomized controlled trial of a commercial diet and exercise weight loss program in minority breast cancer survivors

Objective:

Obesity is associated with poorer breast cancer outcomes and losing weight postdiagnosis may improve survival. As Hispanic and black women have poorer breast cancer prognosis than non‐Hispanic whites diagnosed at similar age and stage, and have higher rates of obesity, effective weight loss strategies are needed. We piloted a randomized, waitlist‐controlled, crossover study to examine the effects and feasibility of the commercial Curves weight loss program among Hispanic, African American and Afro‐Caribbean breast cancer survivors.

Design and Methods:

Women with stage 0–IIIa breast cancer ≥6 months posttreatment, sedentary, and BMI ≥25 kg/m² were randomized to the immediate arm (IA): 6 months of the Curves program followed by 6 months of observation; or the waitlist control arm (WCA): 6 months of observation followed by 6 months of the Curves program. The Curves program uses a 30‐min exercise circuit and a high‐vegetable/low‐fat/calorie‐restricted diet.

Results:

A total of 42 women enrolled (79% Hispanic, 21% black), mean age 51 (range 32–69) and mean BMI 33.2(±5.9) kg/m²; 91% were retained at month 12. At month 6, women in the IA lost an average 3.3% (±3.5%) of body weight (range: 1.7% gain to 10.6% loss), as compared with 1.8% (±2.9%) weight loss in the WCA (P = 0.04). At month 12, on average women in the IA regained some but not all of the weight lost during the first 6 months (P = 0.02).

Conclusions:

Minority breast cancer survivors were recruited and retained in a weight loss study. Six months of the Curves program resulted in moderate weight loss, but weight loss was not maintained postintervention. Future interventions should identify methods to increase uptake and maintenance of weight loss behaviors.     

Obesity and C-reactive protein levels among white, black, and hispanic US adults

Objective: Studies suggest that obesity's adverse impact on cardiovascular mortality may be reduced in African Americans relative to white Americans. We examined whether obesity's association with novel cardiovascular risk factors such as C‐reactive protein (CRP) also varies by race and ethnicity. Methods and Procedures: We analyzed data from 10,492 white, African‐American, and Hispanic‐American participants of the 1999–2004 National Health and Nutrition Examination Survey, who were aged 20 years and older, with a BMI ≥18.5 kg/m² and CRP ≤10 mg/l. We fit sex‐specific multivariable models of the association of BMI or waist circumference with log CRP levels and tested for interactions of BMI or waist circumference with race/ethnicity. Results: Higher BMI was significantly associated with higher CRP in all racial/ethnic groups for both men and women (P > 0.05 for BMI–race/ethnicity interaction) before and after adjustment for age, education, and health behaviors. Larger waist circumference was also associated with higher CRP levels in all racial/ethnic groups before and after adjustment; among women, the relationship was strongest for Mexican Hispanics (P < 0.01 for waist circumference–race/ethnicity interaction). Results were similar after additional adjustment for medications that might affect CRP levels. Discussion: The association between obesity and CRP is at least as strong in African Americans and Hispanic Americans as in white Americans. Racial differences in the relationship between obesity and cardiovascular mortality are unlikely to be due to racial differences in obesity's impact on CRP.