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.

Empirical evidence does not support an association between less ambitious pre-treatment goals and better treatment outcomes: a meta-analysis.

Setting realistic weight loss goals may play a role in weight loss. We abstracted data from randomized controlled trials and observational studies conducted between 1998 and 2012 concerning the association of weight loss goals with weight loss. Studies included those that (i) were conducted in humans; (ii) delivered a weight loss intervention; (iii) lasted ≥6 weeks; (iv) assessed baseline weight loss goals; (vi) assessed pre- and post-weight either in the form of body mass index or some other measure that could be converted to weight loss based on information included in the original study or later provided by the author(s); and (vii) assessed the correlation between weight loss goals and final weight loss or provided data to calculate the correlation. Studies that included interventions to modify weight loss goals were excluded. Eleven studies met inclusion criteria. The overall correlation between goal weight and weight at intervention completion was small and statistically insignificant (ρ=0.0 5 ; P = 0.20). The current evidence does not demonstrate that setting realistic goals leads to more favourable weight loss outcomes. Thus, our field may wish to reconsider the value of setting realistic goals in successful weight loss.

A genotype risk score predicts type 2 diabetes from young adulthood: the CARDIA study.

AIMS/HYPOTHESIS: Genotype does not change over the life course and may thus facilitate earlier identification of individuals at high risk for type 2 diabetes. We hypothesised that a genotype score predicts incident type 2 diabetes from young adulthood and improves diabetes prediction models based on clinical risk factors alone. METHODS: The Coronary Artery Risk Development in Young Adults (CARDIA) study followed young adults (aged 18-30 years, mean age 25) serially into middle adulthood. We used Cox regression to build nested prediction models for incident type 2 diabetes based on clinical risk factors assessed in young adulthood (age, sex, race, parental history of diabetes, BMI, mean arterial pressure, fasting glucose, HDL-cholesterol and triacylglyercol), without and with a 38-variant genotype score. Models were compared with C statistics and continuous net reclassification improvement indices (NRI). RESULTS: Of 2,439 participants, 830 (34%) were black and 249 (10%) had a BMI ≥ 30 kg/m(2) at baseline. Over a mean 23.9 years of follow-up, 215 (8.8%) participants developed type 2 diabetes. The genotype score significantly predicted incident diabetes in all models, with an HR of 1.08 per risk allele (95% CI 1.04, 1.13) in the full model. The addition of the score to the full model modestly improved reclassification (continuous NRI 0.285; 95% CI 0.126, 0.433) but not discrimination (C statistics 0.824 and 0.829 in full models with and without score). Race-stratified analyses were similar. CONCLUSIONS/INTERPRETATION: Knowledge of genotype predicts type 2 diabetes over 25 years in white and black young adults but may not improve prediction over routine clinical measurements.