Getting to the height of the matter: the relationship between stature and adiposity in pre-pubertal children.

OBJECTIVE: Height has been inversely associated with cardiometabolic disease, with adiposity as the proposed contributor. Childhood represents a time when underlying metabolic pathways converge to determine growth. Although the extent to which influence is relevant, insulin, as a key growth signaling factor, likely provides key insight into mechanisms linking height and adiposity. Insulin concentration displays well-established sex and racial differences, with hyperinsulinemia more common among African Americans (AA) females relative to European Americans (EA). The objective of our study was to evaluate the relationship between height and adiposity in children. In addition, a secondary objective was to evaluate potential moderation by insulin concentration. DESIGN: Seventy-two pre-pubertal children aged 4-10 years (mu = 6.6 +/- .2) participated. MAIN OUTCOME MEASURES: Percent fat was assessed by DXA and fasting insulin by serum assay. RESULTS: Height was positively associated with percent fat in the overall sample (P = .04). When evaluated according to age, an association was identified at age seven years (P = .02). When evaluated by sex, a positive relationship was apparent only in AA girls (P = .05). Inclusion of insulin in the model attenuated all significant associations, barring marginal significance in those aged seven years (P = .08). CONCLUSIONS: A positive relationship between height and adiposity is apparent, particularly among those in younger years, which is contrary to what has been consistently reported in adults. Interestingly, age seven years was identified as a point of race-associated divergence in body composition. The degree to which growth-related processes in childhood underlie developmental origins of health disparities warrants further study.

Macronutrient intake influences the effect of 25-hydroxy-vitamin d status on metabolic syndrome outcomes in african american girls.

The objectives were to determine the effect of macronutrient modification on vitamin D status and if change in 25-hydroxy-vitamin D concentration influences components of metabolic syndrome in obese African American girls. Methods. Five-week intervention using reduced CHO (43% carbohydrate; 27% fat: SPEC) versus standard CHO (55% carbohydrate; 40% fat: STAN) eucaloric diet. Subjects were 28 obese African American females, aged 9-14 years. Dual energy X-ray absorptiometry and meal test were performed at baseline and five weeks. Results. Approximately 30% of girls had metabolic syndrome. Serum 25OHD increased in both groups at five weeks [STAN: 20.3 ± 1.1 to 22.4 ± 1.1 (P < 0.05) versus SPEC: 16.1 ± 1.0 to 16.8 ± 1.0 (P = 0.05)]. The STAN group, increased 25OHD concentration over five weeks (P < 0.05), which was positively related to triglycerides (P < 0.001) and inversely associated with total cholesterol (P < 0.001) and LDL (P < 0.001). The SPEC group, had increase in 25OHD (P = 0.05), which was positively related to fasting insulin (P < 0.001) and insulin sensitivity while inversely associated with fasting glucose (P < 0.05). The contribution of vitamin D status to metabolic syndrome parameters differs according to macronutrient intake. Improvement in 25OHD may improve fasting glucose, insulin sensitivity, and LDL; however, macronutrient intake warrants consideration.

Reduced carbohydrate diet to improve metabolic outcomes and decrease adiposity in obese peripubertal African American girls.

OBJECTIVE: Obesity prevalence among African American (AA) girls is higher than that in other groups. Because typical energy-restriction obesity treatment strategies have had limited success, alterations in macronutrient composition may effectively improve metabolic outcomes in this population and affect future body composition trajectories. The objective was to evaluate the efficacy of a moderately restricted carbohydrate (CHO) versus a standard CHO diet on weight/fat loss and metabolic parameters in overweight/obese AA girls ages 9 to 14 years. METHODS: A total of 26 AA girls (ranging from 92nd body mass index percentile and above) were assigned to either a reduced- (SPEC: 42% energy from CHO, n = 12) or a standard- (STAN: 55% of energy from CHO, n = 14) CHO diet (protein held constant) for 16 weeks. All of the meals were provided and clinically tailored to meet the estimated energy requirements (resting energy expenditure × 1.2 in eucaloric phase and resting energy expenditure × 1.2 - 1000 kcal in energy deficit phase). The first 5 weeks encompassed a eucaloric phase evaluating metabolic changes in the absence of weight change. The subsequent 11 weeks were hypocaloric (1000 kcal/day deficit) to promote weight/fat loss. Meal tests were performed during the eucaloric phase for metabolic analyses. Dual-energy x-ray absorptiometry was used to evaluate body composition. RESULTS: Both groups experienced reductions in weight/adiposity, but the difference did not reach significance. The solid meal test indicated improved glucose/insulin homeostasis on the SPEC diet up to 3 hours postingestion. In addition, significantly lower triglycerides (P < 0.001) were observed on the SPEC diet. CONCLUSIONS: Dietary CHO reduction favorably influences metabolic parameters but did not result in greater weight/fat loss relative to a standard diet in obese AA girls. Future research is needed to determine long-term effectiveness of a reduced CHO diet on glucose and insulin homeostasis and how it may apply to weight maintenance/fat loss during development alone and/or in combination with additional weight loss/metabolic improvement strategies.