Lifestyle variables, non-traditional cardiovascular risk factors, and the metabolic syndrome in an Aboriginal Canadian population

Objective : To examine lifestyle factors associated with metabolic syndrome (MetS) and to explore the relationships between MetS and non‐traditional cardiovascular disease risk factors [adiponectin, leptin, C‐reactive protein (CRP), interleukin‐6 (IL‐6), and serum amyloid A (SAA)] in an isolated Aboriginal Canadian community. Research Methods and Procedures : Data were obtained from 360 non‐diabetic adults participating in a population‐based study of Aboriginal Canadians. Fasting samples were drawn for glucose, insulin, lipids, adiponectin, leptin, CRP, IL‐6, and SAA. Percentage body fat was measured using bioelectrical impedance analysis. Past year physical activity and fitness level were assessed. MetS was diagnosed according to the criteria of the National Cholesterol Education Program, the World Health Organization, and the International Diabetes Federation. Results : The results showed that older age, higher percentage body fat, and lower fitness levels were associated with increased odds of MetS regardless of MetS definition and subject gender. Past year physical activity was independently related with the World Health Organization‐MetS in male subjects. Subjects with MetS had significantly higher leptin, CRP, IL‐6, and SAA levels and lower adiponectin levels; however, only adiponectin remained significantly low after adjustment for age and percentage body fat. Discussion : The study showed that higher percentage body fat and lower physical activity and fitness were associated with a higher prevalence of MetS in this Aboriginal community and that hypoadiponectinemia was independently associated with MetS.     

Comparison of demography, diet, lifestyle, and serum lipid levels between the Guangxi Bai Ku Yao and Han populations

Bai Ku Yao is an isolated subgroup of the Yao minority in China. Little is known about dyslipidemia in this population. The aim of this study was to compare the effects of demography, diet, and lifestyle on serum lipid levels between the Bai Ku Yao and Han populations. A total of 1,170 subjects of Bai Ku Yao and 1,173 subjects of Han Chinese aged 15-89 years were surveyed by a stratified randomized cluster sampling. The levels of total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol, apolipoprotein A-I (apoA-I), and apoB were significantly lower in Bai Ku Yao than in Han. Physical activity level and total dietary fiber intake were higher, whereas body mass index (BMI), waist circumference, total energy intake, and total fat intake were lower in Bai Ku Yao than in Han. Hyperlipidemia was positively correlated with BMI, waist circumference, and total energy and total fat intakes and negatively associated with physical activity level and total dietary fiber intake in both populations, but it was positively associated with age and alcohol consumption only in Han. The differences in the lipid profiles between the two ethnic groups were associated with different dietary habits, lifestyle choices, and levels of physical activities.     

The Association of Body Weight,Dietary Intake,and Energy Expenditure with Dietary Restraint and Disinhibition

LAWSON, OLGA J, DONALD A WILLIAMSON, CATHERINE M CHAMPAGNE, JAMES P DELANY, ELLEN R BROOKS, PAULA M HOWAT, PATRICIA J WOZNIAK, GEORGE A BRAY AND DONNA H RYAN. The association of body weight, dietary intake, and energy expenditure with dietary restraint and disinhibition. Obes Res. 1995;3:153–161. The hypotheses that dieting and/or overeating are associated with adiposity, eating disturbances, and lowered energy expenditure were tested in this study. A sample of 44 premenopausal women scoring high and low on measures of dietary restraint and disinhibition of dietary control, as measured by the Three Factor Eating Questionnaire, was studied. A 2 × 2 factorial design was employed (High/Low Restraint x High/Low Disinhibition). Dependent variables were: body composition, dietary intake, activity, resting metabolic rate, and thermic effect of food. Unrestrained overeaters (Low Restraint/High Disinhibition group) were very obese. High Dietary Restraint was associated with intent to diet and controlled eating. High scores on the Disinhibition Scale were associated with episodic overeating. Groups did not differ in resting metabolic rate (controlled for fat-free mass). Lower thermic effect of food was found to be associated with the obesity found in High Disinhibition subjects. Thus, Dietary Restraint was not associated with significant adverse effects upon physical or psychological health. High Disinhibition, however, was associated with adiposity and significant disturbances of eating.     

Intake compensates for resting metabolic rate variation in female C57BL/6J mice fed high-fat diets

Objective: The literature is divided over whether variation in resting metabolic rate (RMR) is related to subsequent obesity. We set out to see whether the effect of RMR on weight gain in mice could be revealed with high‐fat feeding. Research Methods and Procedures: Female C57BL/6J mice received a low‐ (10 kcal%fat n = 47), medium‐ (45 kcal%fat n = 50), or high‐fat diet (60 kcal%fat n = 50) for 12 weeks. Pre‐treatment RMR was measured by indirect calorimetry. Body composition was estimated using DXA before and after treatment. Results: Mice on the high‐fat diet gained 39% of body mass, whereas control animals gained 3.5%. There was no interaction between RMR and dietary type on weight gain, and there was no association between weight gain and RMR for any of the treatments. RMR accounted for 2.4% of the variation in pre‐treatment food intake corrected for initial body mass; however, the gradient of this relationship indicated that variations in RMR were, on average, compensated for by adjustments in food intake. Discussion: Individual variations in RMR did not predispose mice to weight gain independent of the dietary treatment. Deviations from the relationship between RMR and food intake were not associated with weight gain. This suggests that variations in energy expenditure, caused by RMR and physical activity, are closely linked to dietary intake, and, therefore, well compensated. Individual variations in the strength of this association may underpin individual variability in the responses to diet.     

Energy intake, diet composition, energy expenditure, and body fatness of adolescents in northern Greece

Objective: The purpose of this study was to examine energy intake, energy expenditure, diet composition, and obesity of adolescents in Northern Greece. Research Methods and Procedures: Anthropometric measurements were taken for all participants. Height, weight, and skinfold thickness at two sites were measured. BMI and percentage body fat were calculated. Energy intake and macronutrient and micronutrient intakes were determined by a 3‐day weighed dietary diary. Energy expenditure was calculated based on calculated resting metabolic rate (RMR) 1 multiplied by an activity factor based on reported physical activity. Results: Thirty‐one percent of boys and 21% of girls had BMI corresponding to ≥25 kg/m² at 18 years and were classified as overweight. Both overweight boys and girls reported a lower energy intake compared with their non‐overweight counterparts when expressed as kilocalories per kilogram body weight. Overweight children had a higher negative energy balance. Both overweight and non‐overweight adolescents had higher than recommended fat intakes. Mean daily carbohydrate, protein, and fat intake, expressed as grams per kilogram body weight, of overweight adolescents were significantly lower compared with the non‐overweight adolescents. Total daily carbohydrate intake, when expressed in grams, was found to be higher for non‐overweight adolescents. Both overweight boys and girls had lower iron intakes than their non‐overweight counterparts. Overweight boys had statistically lower fiber and niacin intakes than non‐overweight boys. Both overweight and non‐overweight adolescents had lower than recommended iron intakes. Furthermore, overweight adolescents consumed more snacks (potato chips, chocolate bars, pizza, cheese pie, and cream pie), more sugar, jam, and honey, and fewer legumes, vegetables, and fruits than their non‐overweight counterparts. Discussion: Reported energy intake of overweight adolescents was lower than their non‐overweight counterparts. Regarding diet composition overweight subjects had significantly lower intakes of carbohydrates compared with non‐overweight subjects. The food consumption pattern of overweight children showed less adherence to the traditional Mediterranean diet.     

Body macronutrient composition is predicted by lipid and not protein content of the diet

Diet is an important determinant of fitness‐related traits including growth, reproduction, and survival. Recent work has suggested that variation in protein:lipid ratio and particularly the amount of protein in the diet is a key nutritional parameter. However, the traits that mediate the link between dietary macronutrient ratio and fitness‐related traits are less well understood. An obvious candidate is body composition, given its well‐known link to health. Here, we investigate the relationship between dietary and body macronutrient composition using a first‐generation laboratory population of a freshwater fish, the three‐spine stickleback (Gasterosteus aculeatus). Carbohydrate is relatively unimportant in the diet of predatory fish, facilitating the exploration of how dietary protein‐to‐lipid ratio affects their relative deposition in the body. We find a significant effect of lipid intake, rather than protein, on body protein:lipid ratio. Importantly, this was not a result of absorbing macronutrients in relation to their relative abundance in the diet, as the carcass protein:lipid ratios differed from those of the diets, with ratios usually lower in the body than in the diet. This indicates that individuals can moderate their utilization, or uptake, of ingested macronutrients to reach a target balance within the body. We found no effect of diet on swimming endurance, activity, or testes size. However, there was an effect of weight on testes size, with larger males having larger testes. Our results provide evidence for the adjustment of body protein:lipid ratio away from that of the diet. As dietary lipid intake was the key determinant of body composition, we suggest this occurs via metabolism of excess protein, which conflicts with the predictions of the protein leverage hypothesis. These results could imply that the conversion and excretion of protein is one of the causes of the survival costs associated with high‐protein diets.     

Dietary Fat Intake and Insulin Resistance in Black and White Children

Objective: The purpose of this study was to determine whether dietary fat intake above current Acceptable Macronutrient Distribution Range (AMDR) guidelines was associated with greater insulin resistance in black and white children. Research Methods and Procedures: We studied 142 healthy children (n = 81 whites, n = 61 blacks), 6.5 to 14 years old. Dietary composition was determined by repeated 24‐hour dietary recall, body composition by DXA, visceral fat by computed tomography, and insulin sensitivity (SI) and acute insulin response to glucose (AIRg) by frequently sampled intravenous glucose tolerance test. Subjects were categorized by ethnicity (white/black) and dietary fat intake (above‐AMDR/within‐AMDR guidelines), and differences were analyzed by 2 × 2 analysis of covariance, adjusting for covariates. Results: After adjusting for total body fat, gender, and Tanner stage, subjects consuming dietary fat above AMDR intake guidelines had lower SI and higher AIRg. This effect was specific to black children (32% lower SI and 62% higher AIRg in above‐AMDR compared with within‐AMDR blacks) and was not seen in whites. Discussion: In black, but not white, children, those with dietary fat intake above current AMDR guidelines had lower SI and higher AIRg than those who met AMDR guidelines. These findings support current AMDR guidelines for dietary fat in black children and adolescents. The mechanism(s) underlying the ethnic differences in the relationship between dietary fat intake and SI in children require further investigation.     

Physical Training Improves Body Composition of Black Obese 7- to 11-Year-Old Girls

We determined the effect of supervised physical training, without dietary intervention, on body composition of obese girls. The subjects were 25 obese 7-to 11-year-old black girls, divided into physical training and lifestyle education groups which were comparable on baseline body composition; 22 girls finished all aspects of the study. Twelve girls engaged in aerobic training (10 weeks, 5 days/week) while 10 engaged in weekly lifestyle discussions without formal physical training. Total body and regional body composition were measured with dual energy x-ray absorptiometry, skin folds and circumferences. Aerobic fitness was measured by heart rate response to sub maximal treadmill exercise. The physical training group attended 94% of scheduled sessions and kept their heart rates at an average of 163 bpm for 28 minutes/session. The lifestyle group attended 95% of their sessions; they remained stable in aerobic fitness and most body composition measurements. The physical training group showed a significant improvement in aerobic fitness and a significant decline of 1.4% body fat. Skin fold and circumference indices of fatness also declined significantly in physical training, without dietary intervention, improved the fitness and body composition of obese black girls.     

Evaluation of the Influence of Cardiorespiratory Fitness on Diverse Health Risk Factors,Independent of Waist Circumference,in 40‐Year‐Old Flemish Males

Objective: To examine whether cardiorespiratory fitness is associated with health risk factors, independent of abdominal obesity (waist circumference). Research Methods and Procedures: Data from 141 40‐year‐old Flemish male subjects were used in a cross‐sectional design. The main outcome measure in this study was the health risk profile, composed of lipid parameters, blood pressure, and body composition parameters. Data were analyzed by regression analysis and by means of analysis of covariance with waist circumference (WC) as covariate and cardiorespiratory fitness as source of variance. Results: The data demonstrated that cardiorespiratory fitness was significantly associated with triglycerides, with the ratio of total cholesterol/serum high density lipoprotein cholesterol, and with percent body fat, independent of an association with WC. Discussion: Major findings of the present cross‐sectional study indicate that a high WC is associated with adverse health‐related lipid profile and body composition characteristics and that relatively high levels of aerobic fitness attenuate the health risk associated with a large WC.     

Influence of Body Composition on the Accuracy of Reported Energy Intake in Children

Objective: Mis‐reporting dietary intake is a substantial barrier to understanding the role of dietary behavior in disease. Work with adults indicates that heavier individuals under‐report dietary intake and that under‐reporting may be macronutrient‐specific. Whether weight status and macronutrient intake influence the accuracy of dietary reports among children, however, is less clear. This research evaluated children's dietary reporting accuracy as a function of their relative weight, body composition, and macronutrient intake. Research Methods and Procedures: Participants included 146 4‐ to 11‐year‐old children. Reported energy intake was determined by interviewing children in the presence of parents, using three multiple pass, 24‐hour recalls. Children were classified as having had an under‐reported, accurately reported, or over‐reported dietary intake relative to total energy expenditure, as measured by doubly labeled water. Reporting accuracy was examined as a function of children's body weight, body composition (using dual energy x‐ray absorptiometry), and macronutrient intake. Results: Average reported intake was, on average, 14% greater than children's estimated expenditure (p < 0.01). Reporting accuracy varied as a function of children's relative weight and body composition; under‐reporting tended to occur among heavier children, having the highest body fat content (p < 0.0001) and relative weight (p < 0.0001). Discussion: These findings suggest that weight status influences the accuracy of dietary reports made by children and their parents. More research is needed to address possible psychological and social factors that introduce bias in reporting children's dietary data.     

Reexamining Obesigenic Families: Parents’ Obesity‐related Behaviors Predict Girls’ Change in BMI

Objective: It has been shown that girls from families in which mothers and fathers had high dietary intake and low physical activity (i.e., obesigenic families) were at increased risk of obesity from ages 5 to 7 years. This follow‐up study uses additional data collected when girls were 9 and 11 years old to examine whether girls from obesigenic families continued to show greater increases in BMI over time and reported unhealthy dietary and activity patterns. Research Methods and Procedures: Families from the original cohort were reexamined when girls were 9 and 11 years of age. Parents’ and girls’ BMI, dietary intake, and physical activity and girls’ percentage body fat and television viewing were assessed. Results: In comparison with girls from non‐obesigenic families, girls from obesigenic families showed greater increases in BMI and BMI z score from ages 5 to 7 years that were maintained across ages 7 to 11 years. Furthermore, girls from obesigenic families had higher percentage body fat at ages 9 and 11 years. These results were independent of parents’ BMI. Additional findings showed that girls from obesigenic families had diets higher in percentage fat and had higher levels of television viewing than girls from non‐obesigenic families. Discussion: The environment that parents create, by way of their own dietary and physical activity behaviors, may have a lasting negative effect on children's weight trajectories and their emerging obesity risk behaviors, such as their dietary patterns. These findings further highlight the importance of the family in establishing children's obesity risk and the necessity of targeting parents of young children in obesity prevention efforts.     

Effect of Protein Intake on Bone Mineralization during Weight Loss: A 6‐Month Trial

Objective: The long‐term effect of dietary protein on bone mineralization is not well understood. Research Methods and Procedures: Sixty‐five overweight (body mass index, 25 to 29.9 kg/m²) or obese (≥30 kg/m²) subjects were enrolled in a randomized, placebo‐controlled, 6‐month dietary‐intervention study comparing two controlled ad libitum diets with matched fat contents: high protein (HP) or low protein (LP). Body composition was assessed by DXA. Results: In the HP group, dietary‐protein intake increased from 91.4 g/d to a 6‐month intervention mean of 107.8 g/d (p < 0.05) and decreased in the LP group from 91.1 g/d to 70.4 g/d (p < 0.05). Total weight loss after 6 months was 8.9 kg in the HP group, 5.1 kg in the LP group, and none in the control group. After 6 months, bone mineral content (BMC) had declined by 111 ± 13 g (4%) in the HP group and by 85 ± 13 g (3%) in the LP group (not significant). Loss of BMC was more positively correlated with loss of body fat mass (r = 0.83; p < 0.0001) than with loss of body weight. Six‐month BMC loss, adjusted for differences in fat loss, was greater in the LP group than in the HP group [difference in LP vs. HP, 44.8 g (95% confidence interval, 16 to 73.8 g); p < 0.05]. Independent of change in body weight and composition during the intervention, highprotein intake was associated with a diminished loss of BMC (p < 0.01). Discussion: Body‐fat loss was the major determinant of loss of BMC, and we found no adverse effects of 6 months of high‐protein intake on BMC.     

Long-term effects of dietary glycemic index on adiposity, energy metabolism, and physical activity in mice

A high-glycemic index (GI) diet has been shown to increase adiposity in rodents; however, the long-term metabolic effects of a low- and high-GI diet have not been examined. In this study, a total of 48 male 129SvPas mice were fed diets high in either rapidly absorbed carbohydrate (RAC; high GI) or slowly absorbed carbohydrate (SAC; low GI) for up to 40 wk. Diets were controlled for macronutrient and micronutrient content, differing only in starch type. Body composition and insulin sensitivity were measured longitudinally by DEXA scan and oral glucose tolerance test, respectively. Food intake, respiratory quotient, physical activity, and energy expenditure were assessed using metabolic cages. Despite having similar mean body weights, mice fed the RAC diet had 40% greater body fat by the end of the study and a mean 2.2-fold greater insulin resistance compared with mice fed the SAC diet. Respiratory quotient was higher in the RAC group, indicating comparatively less fat oxidation. Although no differences in energy expenditure were observed throughout the study, total physical activity was 45% higher for the SAC-fed mice after 38 wk of feeding. We conclude that, in this animal model, 1) the effect of GI on body composition is mediated by changes in substrate oxidation, not energy intake; 2) a high-GI diet causes insulin resistance; and 3) dietary composition can affect physical activity level.     

Dietary protein supplementation and its consequences for intake,digestion, and physical activity of a carnivorous marsupial,Sminthopsis crassicaudata

Diet regulation behavior can mediate the consequences of imbalanced diets for animal well‐being, particularly for captive species that have little dietary choice. Dasyurids (carnivorous marsupials) are of conservation concern in Australia, and many species are in captive breeding programmes. However, their nutrient targets and dietary regulation behaviors are poorly understood, a limitation that may decrease the breeding success and well‐being of captive animals. We tested how dietary protein content influenced the intake and utilization of nutrients, physical activity, and body mass of fat‐tailed dunnarts Sminthopsis crassicaudata. Twelve adult dunnarts from six sibling pairs (one female and one male per pair) were provided ad libitum access to three diets in a repeated measures design: cat food, cat food supplemented with raw lean beef (1:1), and cat food supplemented with cooked lean beef (1:1). Food intake, activity level, and fecal output were measured daily. Dunnarts significantly decreased food intake, increased protein digestion, and physical activity, but body mass was unchanged when on the high‐protein diet compared to the normal cat food diet. These observations suggest a capacity of dunnarts to maintain constant body mass using a dynamic balance of feeding, digestion, and activity. We also found a significant effect of family, with differences between families as large as the difference between the diet treatments, suggesting a genetic component to diet selection. The nutrient regulation responses of dunnarts to high‐protein diets and the strong family effects provide important messages for the management of populations of small carnivores, including the aspects of dietary manipulation and conservation of genetic diversity.     

Strong influence of dietary intake and physical activity on body fatness in elderly Japanese men: age-associated loss of polygenic resistance against obesity

Genome-wide association studies identified single nucleotide polymorphisms (SNPs) associated with body mass index (BMI) in middle-aged populations; however, it is unclear whether these SNPs are associated with body fatness in elderly people. We examined the association between genetic risk score (GRS) from BMI-associated SNPs and body fatness in elderly Japanese men. We also examined the contribution of GRS, dietary macronutrient intake, and physical activity to body fatness by different age groups. GRS was calculated from 10 BMI-associated SNPs in 84 middle-aged (30–64 years) and 97 elderly (65–79 years) Japanese men; subjects were divided into low, middle, and high GRS groups. Dietary macronutrient intake was assessed using a questionnaire, and physical activity was evaluated using both a questionnaire and an accelerometer. The middle-aged individuals with a high GRS had greater BMI; waist circumference; and total abdominal fat, visceral fat, and subcutaneous fat areas than the middle-aged individuals with low GRS, whereas the indicators were not different between the GRS groups in elderly individuals. Multiple linear regression analysis showed that GRS was the strongest predictor of BMI, total abdominal fat, and visceral fat in the middle-aged group, whereas fat, alcohol, and protein intakes or vigorous-intensity physical activity were more strongly associated with these indicators than was GRS in the elderly group. These results suggest that GRS from BMI-associated SNPs is not predictive of body fatness in elderly Japanese men. The stronger contribution of dietary macronutrient intake and physical activity to body fatness may attenuate the genetic predisposition in elderly men.     

Alcohol intake, insulin resistance, and abdominal obesity in elderly men

Objective: Moderate and high alcohol intake have been associated with decreased and increased risk of type 2 diabetes, respectively. Insulin resistance, insulin secretion, and abdominal obesity are major predictors of diabetes, but the links with alcohol intake remain contradictory because of limited data. Research Methods and Procedures: In a population‐based cohort of 807 men (age, 70 years), we studied whether alcohol intake was related to insulin sensitivity, measured with the gold standard technique (euglycemic clamp), insulin secretion (early insulin response), or adiposity [BMI, waist circumference (WC), waist‐to‐hip ratio]. Alcohol intake was self‐reported (questionnaire) and was assessed from a validated 7‐day dietary record. The cross‐sectional associations were evaluated using multivariable linear regression, adjusting for smoking, education level, physical activity, dietary total energy intake, hypertension, diabetes, triglycerides, and cholesterol. Results: In multivariable models, self‐estimated alcohol intake was not related to insulin sensitivity, early insulin response, or BMI, but was positively related to WC (β‐coefficient, 0.77; 95% confidence interval, 0.15 to 1.39; p = 0.02) and waist‐to‐hip ratio (0.006 [0.002–0.009], p = 0.003). The association with WC and waist‐to‐hip ratio was most pronounced in men in the lowest tertile of BMI. The results using dietary records were similar. Discussion: Evaluated in a large sample in elderly men, neither insulin sensitivity measured by clamp technique nor insulin secretion was significantly associated with alcohol intake. However, high alcohol intake was associated with abdominal obesity, which might explain the higher diabetes risk previously observed in high alcohol consumers.     

Dietary linolenic acid and fasting glucose and insulin: the National Heart, Lung, and Blood Institute Family Heart Study

Objective: To assess whether dietary linolenic acid is associated with fasting insulin and glucose. Research Methods and Procedures: In a cross‐sectional design, we studied 3993 non‐diabetic participants of the National Heart, Lung, and Blood Institute Family Heart Study 25 to 93 years of age. Linolenic acid was assessed through a food frequency questionnaire, and laboratory data were obtained after at least a 12‐hour fast. We used generalized linear models to calculate adjusted means of insulin and glucose across quartiles of dietary linolenic acid. Results: From the lowest to the highest sex‐specific quartile of dietary linolenic acid, means ± standard error for logarithmic transformed fasting insulin were 4.06 ± 0.02 (reference), 4.09 ± 0.02, 4.13 ± 0.02, and 4.17 ± 0.02 pM, respectively (trend, p < 0.0001), after adjustment for age, sex, energy intake, waist‐to‐hip ratio, smoking, and high‐density lipoprotein‐cholesterol. When dietary linolenic acid was used as a continuous variable, the multivariable adjusted regression coefficient was 0.42 ± 0.08. There was no association between dietary linolenic acid and fasting glucose (trend p = 0.82). Discussion: Our data suggest that higher consumption of dietary linolenic acid is associated with higher plasma insulin, but not glucose levels, in non‐diabetic subjects. Additional studies are needed to assess whether higher intake of linolenic acid results in an increased insulin secretion and improved glucose use in vivo.     

Ethnic Differences in Correlates of Obesity between Latin‐American and Black Women

Objective: To date, no studies have examined dietary intake, physical activity, and body image in a large sample of Latin‐American and black women recruited using the same methodology. The aim of this study was to examine three potential correlates of obesity (dietary intake, body image, and physical activity) in a large sample of Latin‐American and black women across the weight spectrum. Research Methods and Procedures: Participants were black (n = 271) and Latin‐American (n = 234) adult women who completed a 24‐hour dietary recall and physical activity and body image questionnaires. Results: After controlling for BMI, education, marital status, and number of children, black women consumed more kilocalories, dietary fat (grams), and percent calories from fat than Latin‐American women, who consumed more carbohydrates (grams) and dietary fiber (total and soluble). Black women engaged in more sedentary behavior than Latin‐American women. Although Latin‐American women weighed less than black women, they perceived their current body image as heavier and reported greater body image dissatisfaction than black women. Black women also reported a higher ideal body image than Latin‐American women. Discussion: The combined effect of a diet higher in calories and fat, increased sedentary behavior, and more accepting body image could account for higher rates of obesity among black women. Future studies should further explore cultural attitudes and beliefs related to weight that could provide information for the development of culturally competent obesity interventions.     

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.     

Objectively Measured Intensity of Physical Activity and Adiposity in Middle‐Aged Women

Objective: The aim of this study was to evaluate the relationship between objectively measured physical activity (ACT), particularly intensity of physical activity (iACT), and body fat percentage (BF%) in 278 middle‐aged women. Secondary purposes were to ascertain the association between physical activity duration (dACT) and BF% and the extent to which potentially confounding factors, including total ACT, energy intake, body weight, and season of assessment, influenced the relationship between iACT and BF%. Research Methods and Procedures: A cross‐sectional design was used. Subjects were apparently healthy, 35 to 45 years old, premenopausal, nonsmokers, with BMIs < 30 kg/m². Approximately 90 percent were white, 81% were married, and 37% were college graduates. ACT was assessed using Computer Science and Application accelerometers worn for 7 consecutive days. The accelerometers recorded movement continuously, and activity counts were collapsed into 10‐minute epochs. Intensity was indexed using seven activity count cut‐off points, and duration was based on the number of 10‐minute epochs at each intensity level. BF% was assessed using multiple measurements in the Bod Pod. Energy intake was measured using 7‐day weighed diet records during the same week subjects wore the accelerometers. Results: BF% was strongly and inversely associated with iACT and dACT. Controlling for energy intake and body weight strengthened the relationships among iACT, dACT, and BF%. Control of total ACT weakened the association. Discussion: Engaging in higher intensity and/or longer duration ACT is associated with lower BF% compared with lower intensity and/or shorter durations of activity.