Robert L. Newton

The Relationship of Waist Circumference and BMI to Visceral, Subcutaneous, and Total Body Fat: Sex and Race Differences

The purpose of this study was to examine sex and race differences in the relationship between anthropometric measurements and adiposity in white and African‐American (AA) adults. Visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) areas were measured with computed tomography (CT). Fat mass (FM) was measured with dual‐energy‐X‐ray absorptiometry (DXA). Correlation coefficients were used to assess the relationship of waist circumference (WC) and BMI to VAT, SAT, and FM within sex‐by‐race groups. General linear models were used to compare relationships between WC or BMI, and adiposity across sex and race, within age groups (18–39 and 40–64 years). The sample included 1,667 adults (men: 489 white; 120 AA; women: 666 white, 392 AA). WC and BMI correlations were highest for FM and SAT compared to VAT. Women had higher FM levels than men regardless of WC, but the sex difference in FM was attenuated in younger AA adults with a high BMI. For a given level of WC or BMI, women had higher levels of SAT than men; however, significant interactions indicated that the relationship was not consistent across all levels of BMI and WC. Sex and race differences in VAT varied significantly with WC and BMI. In general, white adults had higher levels of VAT than AA adults at higher levels of BMI and WC. Sex differences, and in some instances race differences, in the relationships between anthropometry and fat‐specific depots demonstrate that these characteristics need to be considered when predicting adiposity from WC or BMI.

Adherence to Exercise Prescriptions: Effects of Prescribing Moderate Versus Higher Levels of Intensity and Frequency

Sedentary adults (N = 379) were randomly assigned in a 2 x 2 design to walk 30 min per day at a frequency of either 3-4 or 5-7 days per week, at an intensity of either 45%-55% or 65%-75% of maximum heart rate reserve. Analyses of exercise accumulated over 6 months showed greater amounts completed in the higher frequency (p = .0001) and moderate intensity (p = .021) conditions. Analyses of percentage of prescribed exercise completed showed greater adherence in the moderate intensity(p = .02) condition. Prescribing a higher frequency increased the accumulation of exercise without a decline in adherence, whereas prescribing a higher intensity decreased adherence and resulted in the completion of less exercise.

Profiles of sedentary behavior in children and adolescents:The US National Health and Nutrition Examination Survey, 2001-2006

OBJECTIVE To describe the prevalence of time spent in sedentary behaviors (e.g., TV/video and computer use) among youth in the US. METHODS The National Health and Nutrition Examination Survey (2001-06) provided data to examine sedentary behavior across age groups (2-5, 6-11, and 12-15 years of age), ethnic groups (European [EA], African [AA], and Mexican American [MA]), and body mass index (BMI) categories (normal weight, overweight, obese). RESULTS The sample included 8 707 (50.7% boys) children aged 2 to 15 years. Seventy percent of the sample was normal weight, 18.1% was overweight, and 11.5% was obese. The total proportion of young people engaged in TV/video viewing, computer use, and total screen time > or = 2 hours daily was 33.0%, 6.7%, and 47.3%, respectively. More boys (49.4%) than girls (45.0%); older (12-15 years: 56.0%) versus younger children (2-5 years: 35.3% and 6-11 years: 49.1%); AA (66.1%) versus EA (42.5%) and MA (46.1%); obese (58.5%) versus overweight (50.8%) versus normal weight (44.6%); and low and middle income (<

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

25 K: 51.4% and

Racial differences in abdominal depot–specific adiposity in white and African American adults

25-45 K: 51.2%) versus high income (>

Efficacy of an internet-based behavioral weight loss program for overweight adolescent African-American girls

45 K: 42.6%) children spent > or = 2 hours daily in screen time. CONCLUSION Nearly half (47%) of US children exceed > or = 2 hours/day of time in sedentary behavior. Further, it appears there are gender, age, ethnic, BMI-defined weight status, and income differences in exceeding > or = 2 hours/day in sedentary behavior. These results will be useful in planning targeted interventions at those populations with a higher prevalence of sedentary behavior.

Wise Mind Project: A School-based Environmental Approach for Preventing Weight Gain in Children

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.

Ethnic-Specific BMI and Waist Circumference Thresholds

BACKGROUND There is increasing interest in understanding racial differences in adiposity in specific body depots as a way to explain differential health risks associated with obesity. OBJECTIVE Our aim was to examine the differences in abdominal visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) between white and African American adults. DESIGN The sample included 1967 adults aged 18-84 y, including 790 white women, 435 African American women, 606 white men, and 136 African American men. Total body fat was measured by using dual-energy X-ray absorptiometry, whereas abdominal VAT and SAT cross-sectional areas (L4-L5 level) were measured by using computed tomography. Sex-specific differences in SAT and VAT between racial groups were analyzed by the use of general linear models, which controlled for age and total body fat. Additional models tested for racial differences in VAT and SAT and controlled for age, total body fat, smoking, and menopausal status. Statistical significance was accepted at P < 0.05. RESULTS Abdominal VAT was significantly higher in white than in African American men and women, even after adjustment for covariates. White women had significantly lower SAT than did African American women, both before and after adjustment for covariates. White men had significantly higher SAT than did African American men, but after adjustment for covariates, their SAT was lower than that of African American men. CONCLUSIONS Abdominal visceral adiposity is significantly greater in white men and women. After adjustment for covariates, white men and women had significantly lower SAT than did African American men and women. The results of this study highlight the heterogeneity of human body fat distribution across racial groups.This trial was registered at clinicaltrials.gov as NCT00959270.

Effect of an Environmental School-Based Obesity Prevention Program on Changes in Body Fat and Body Weight: A Randomized Trial

Objective: This randomized controlled trial tested the efficacy of an internetbased lifestyle behavior modification program for weight management in African-American girls. Design: African-American girls were randomly assigned to an interactive behavioral internet program or an internet health education program, the control condition. The behavioral intervention included internet counseling and was highly interactive. The control intervention was a passive (non-interactive) educational program. Parents were also participants in the study. Participants in both treatment groups met in face-to-face sessions on four occasions over the first 12 weeks of a 6-month intervention. Subjects: The study enrolled 57 African-American adolescent girls (ages 11 to 15 years) who were overweight or obese and had at least one biological parent who was obese [body mass index (BMI) >30 kg/m2]. Of the 57 participants, 50 (88%) completed the 6-month trial. Measurements: Outcome data, including BMI, body weight, body composition, dietary intake, and weight loss behaviors were collected at baseline and 6-months later. A computer server tracked utilization of the websites. Participation in the program was measured by number of “hits” on the website. Results: Compared to the control condition, adolescents in the behavioral treatment lost more body fat (group difference =1.6% body fat) and parents lost significantly more body weight (group difference =2.1 kg). Utilization of the behavioral website by adolescents and parents was associated with positive outcome. Dietary fat intake was lowered for adolescents and parents in the behavioral treatment group. Conclusion: An internet-based behavioral intervention was superior to internet-based health education and yielded decreased body fat for adolescent girls and decreased body weight for parents.

Ethnic differences in self-reported and measured obesity.

Objective: The Wise Mind pilot study compared the efficacy of an environmental approach for prevention of inappropriate weight gain in children with an active control condition that used an environmental approach for modifying expectancies related to the use of alcohol, tobacco, and drugs.