Comparison of Weight-Loss Diets with Different Compositions of Fat, Protein, and Carbohydrates

BACKGROUND: The possible advantage for weight loss of a diet that emphasizes protein, fat, or carbohydrates has not been established, and there are few studies that extend beyond 1 year. METHODS: We randomly assigned 811 overweight adults to one of four diets; the targeted percentages of energy derived from fat, protein, and carbohydrates in the four diets were 20, 15, and 65%; 20, 25, and 55%; 40, 15, and 45%; and 40, 25, and 35%. The diets consisted of similar foods and met guidelines for cardiovascular health. The participants were offered group and individual instructional sessions for 2 years. The primary outcome was the change in body weight after 2 years in two-by-two factorial comparisons of low fat versus high fat and average protein versus high protein and in the comparison of highest and lowest carbohydrate content. RESULTS: At 6 months, participants assigned to each diet had lost an average of 6 kg, which represented 7% of their initial weight; they began to regain weight after 12 months. By 2 years, weight loss remained similar in those who were assigned to a diet with 15% protein and those assigned to a diet with 25% protein (3.0 and 3.6 kg, respectively); in those assigned to a diet with 20% fat and those assigned to a diet with 40% fat (3.3 kg for both groups); and in those assigned to a diet with 65% carbohydrates and those assigned to a diet with 35% carbohydrates (2.9 and 3.4 kg, respectively) (P>0.20 for all comparisons). Among the 80% of participants who completed the trial, the average weight loss was 4 kg; 14 to 15% of the participants had a reduction of at least 10% of their initial body weight. Satiety, hunger, satisfaction with the diet, and attendance at group sessions were similar for all diets; attendance was strongly associated with weight loss (0.2 kg per session attended). The diets improved lipid-related risk factors and fasting insulin levels. CONCLUSIONS: Reduced-calorie diets result in clinically meaningful weight loss regardless of which macronutrients they emphasize

A Clinical Trial of the Effects of Dietary Patterns on Blood Pressure

BACKGROUND: It is known that obesity, sodium intake, and alcohol consumption factors influence blood pressure. In this clinical trial, Dietary Approaches to Stop Hypertension, we assessed the effects of dietary patterns on blood pressure. METHODS: We enrolled 459 adults with systolic blood pressures of less than 160 mm Hg and diastolic blood pressures of 80 to 95 mm Hg. For three weeks, the subjects were fed a control diet that was low in fruits, vegetables, and dairy products, with a fat content typical of the average diet in the United States. They were then randomly assigned to receive for eight weeks the control diet, a diet rich in fruits and vegetables, or a "combination" diet rich in fruits, vegetables, and low-fat dairy products and with reduced saturated and total fat. Sodium intake and body weight were maintained at constant levels. RESULTS: At base line, the mean (+/-SD) systolic and diastolic blood pressures were 131.3+/-10.8 mm Hg and 84.7+/-4.7 mm Hg, respectively. The combination diet reduced systolic and diastolic blood pressure by 5.5 and 3.0 mm Hg more, respectively, than the control diet (P or =140 mm Hg; diastolic pressure, > or =90 mm Hg; or both), the combination diet reduced systolic and diastolic blood pressure by 11.4 and 5.5 mm Hg more, respectively, than the control diet (P<0.001 for each); among the 326 subjects without hypertension, the corresponding reductions were 3.5 mm Hg (P<0.001) and 2.1 mm Hg (P=0.003). CONCLUSIONS: A diet rich in fruits, vegetables, and low-fat dairy foods and with reduced saturated and total fat can substantially lower blood pressure. This diet offers an additional nutritional approach to preventing and treating hypertension

Early sexual maturation, body composition, and obesity in African-American girls.

OBJECTIVE: To describe associations between sexual maturation and body composition in a sample of African-American girls who were participants in phase 1 pilot interventions of the Girls Health Enrichment Multisite Studies. RESEARCH METHODS AND PROCEDURES: Stature, weight, and waist circumference were measured. Pubic hair and breast development were assessed, and body composition was measured by DXA for 147 African-American girls who were 8 to 10 years of age from three field centers. Participants had BMI \u3e or =25th percentile for age (one site) or BMI \u3e or =50th percentile for age. RESULTS: Girls Health Enrichment Multisite Studies girls had greater BMI, fat mass, and percentage body fat than national norms and relatively earlier initiation of breast development and pubic hair. Increasing stages of breast development, but not stages of pubic hair, were related to increased stature, waist circumference, BMI, lean mass, fat mass, and percentage of body fat. Pubescent girls (breast stage \u3e or = 2) were greater than six times as likely to be classified as at risk of overweight (BMI \u3e or = 85th percentile) and greater than eight times as likely to be classified as overweight (BMI \u3e or = 95th percentile) as prepubescent counterparts. Adjusted odds ratios for advanced breast development [breast stage \u3e or = 2 (8 years) or \u3e or = 3 (9 and 10 years)] were 3.6 for risk of overweight and for overweight compared to girls with average or less than average breast development. DISCUSSION: Sexual maturation is important to consider in understanding the classification of overweight and the development of obesity during adolescence. Breast development and pubic hair development should be considered separately for their associations with growth and body composition

Validity and reliability of activity measures in African-American Girls for GEMS

Purpose: To determine the reliability and validity of physical activity monitors and self-report instruments suitable for young African-American girls. Methods: A validation study was conducted by the Girls health Enrichment Multi-site Studies (GEMS) research team to compare an accelerometer with a pedometer and two self-report instruments for assessing physical activity in African-American girls, age 8-9 yr. Girls (N = 68) attended two clinic visits spaced 4 d apart. Each girl wore a MTI/CSA accelerometer (used as the criterion standard for validity) and a pedometer simultaneously for four consecutive days. Girls completed on two occasions a 24-h physical activity checklist of yesterday and usual activities, including sedentary activities (GEMS Activity Questionnaire, GAQ), and a 3-d computerized self-report instrument (Activitygram). Results: Girls were (mean ± SD) 9.0 ± 0.6 yr old and had a body mass index of 19.4 kg.m-2. Reliability measured by intraclass correlations (ICC) and Pearson correlation coefficients (r) were calculated for the MTI/CSA (ICC = 0.37, P \u3c 0.0001), pedometer (ICC = 0.08, P = 0.094), Activitygram (ICC = 0.24) (P = 0.005), and GAQ for physical (r = 0.80, P \u3c 0.0001) and sedentary (r = 0.3-0.5, P \u3c 0.005) activities. Significant Pearson correlations between the MTI/CSA and the other instruments, as a measure of validity, were observed for the 4-d average pedometer score (r = 0.47, P \u3c 0.0001), 3-d average Activitygram score (r = 0.37, P = 0.002), and the average of the two yesterday and two usual GAQ activity scores for a subset of 18 physical activities questions (r = 0.27, P = 0.03; and r = 0.29, P = 0.02, respectively). The MTI/CSA was uncorrelated with single day scores from the three other instruments. Conclusion: The reliability of the instruments tested was acceptable, except the pedometer. Validity correlations were significant when more than one day was used. Self-report instruments need further development for improved reliability and validity

Relation between the changes in physical activity and body-mass index during adolescence: a multicentre longitudinal study

SummaryBackgroundThe role of physical activity in preventing obesity during adolescence remains unknown. We examined changes in activity in relation to changes in body-mass index (BMI) and adiposity in a cohort of 1152 black and 1135 white girls from the USA, who were followed up prospectively from ages 9 or 10 to 18 or 19 years.MethodsBMI and sum of skinfold thickness were assessed annually, whereas habitual activity was assessed at years 1 (baseline), 3, 5, and 7–10. Each girls' overall activity status was categorised as active, moderately active, or inactive. Longitudinal regression models examined associations between changes in activity and in overall activity status with changes in BMI and in sum of skinfold thickness.FindingsEach decline in activity of 10 metabolic equivalent [MET]-times per week was associated with an increase in BMI of 0·14 kg/m2 (SE 0·03) and in sum of skinfold thickness of 0·62 mm (0·17) for black girls, and of 0·09 kg/m2 (0·02) and 0·63 mm (0·13) for white girls. At ages 18 or 19 years, BMI differences between active and inactive girls were 2·98 kg/m2 (p<0·0001) for black girls and 2·10 kg/m2 (p<0·0001) for white girls. Similar results were apparent for sum of skinfold thickness. For moderately active girls, changes in BMI and sum of skinfold thickness were about midway between those for active and inactive girls.InterpretationChanges in activity levels of US girls during adolescence significantly affected changes in BMI and adiposity. Thus, preventing the steep decline in activity during adolescence is an important method to reduce obesity