Search

Gastric bypass surgery (GBP) results in important and sustained weight loss and remarkable improvement of Type 2 diabetes. The favorable change in the incretin gut hormones is thought to be responsible, in part, for diabetes remission after GBP, independent of weight loss. However, the relative role of the change in incretins and of weight loss is difficult to differentiate. After GBP, the plasma concentrations of the incretin hormones glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide increase postprandially by three- to fivefold. The postprandial incretin effect on insulin secretion, blunted in diabetes, improves rapidly after the surgery. In addition to the change in incretins, the pattern of insulin secretion in response to oral glucose changes after GBP, with recovery of the early phase and significant decrease in postprandial glucose levels. These changes were not seen after an equivalent weight loss by diet. The improved insulin release and glucose tolerance after GBP were shown by others to be blocked by the administration of a GLP-1 antagonist, demonstrating that the favorable metabolic changes after GBP are, in part, GLP-1 dependent. The improved incretin levels and effect persist years after GBP, but their long-term effect on glucose metabolism, and on hypoglycemia post GBP are yet unknown. Understanding the mechanisms by which incretin release is exaggerated postprandially after GBP may help develop new less invasive treatment options for obesity and diabetes. Changes in rate of eating, gastric emptying, intestinal transit time, nutrient absorption and sensing, as well as bile acid metabolism, may all be implicated.

To investigate the influence of age, sex, ethnicity and total fatness on central obesity in four ethnic populations.Cross-sectional analysis of study subjects enrolled from 1993 to 2005.A multi-ethnic (Caucasian (CA), African-American (AA), Hispanic-American (HA) and Asian (As)) convenience sample of 604 men and 1192 women (aged 18-96 years, body mass index 15.93-45.80 kg/m(2)).Total body fat (TBF) and truncal fat were measured by dual-energy X-ray absorptiometry. General linear regression models were used to test for independent associations with log(10)-transformed truncal fat.For all ethnicities, men had a lower percent body fat and more truncal fat than women. Log(10-)transformed truncal fat increased with TBF approximately as a square root function. At older ages, there was a greater amount of truncal fat in CA, HA and As men (approximately 0.20-0.25 kg/decade) with the effect more pronounced in AA men ( approximately 0.33 kg/decade). For women, the increment of truncal fat per decade was reduced in CA and AA women (approximately 0.07 kg) compared with As and HA women (approximately 0.33 kg). Adjusted for mean values of covariates in our sample, AA had less truncal fat than As.The accumulation of truncal fat is strongly related to age, ethnicity and total fatness in both men and women.

BACKGROUND: The energy content of weight change is assumed to be sex- and age-neutral at 3500 kcal/pound or 32.2 MJ/kg. OBJECTIVES: As sexual dimorphism in body composition generally exists in mammals, the primary hypothesis advanced and tested was that the energy content of weight change differs between men and women. DESIGN: The energy content of 129 adult men and 287 women was measured by neutron activation analysis. Cross-sectional energy content prediction models were developed and then evaluated in two longitudinal samples: one that used the same methods in 26 obese women losing weight; and the other a compilation of 18 previously reported weight change–body composition studies. RESULTS: Multiple regression modeling identified weight, sex, age and height as total energy content predictor variables with significant sex×weight (P