Obesity in free-ranging rhesus macaques.

Spontaneous obesity in free-ranging rhesus macaques (Macaca mulatta) was assessed in terms of body size, body fat distribution, endocrinological/metabolic indices, and social and familial factors. Eleven animals (six females, five males), or 7% of the adult population surveyed, were defined as obese on the basis of morphometric indices of adiposity > 2 s.d. above the mean for adults in this colony. The age of the obese animals ranged from 9-16 years; obese males were older than females (average 14 vs. 12 years), but this difference was not significant. Mean body weights for obese males and females were 14.1 +/- 0.5 and 13.5 +/- 0.7 kg, respectively. There were no gender differences in either the incidence of obesity or measures of body fat. Serum concentrations of cholesterol and testosterone were not significantly different between obese and nonobese monkeys. Serum triglyceride levels were somewhat higher in obese animals, but this difference was not significant. Glucose clearance was within normal limits in both obese and age- and sex-matched non-obese monkeys (> 2% per min). Although increased adiposity was significantly correlated with fasting insulin and the insulin response to glucose loading, differences between obese and non-obese animals in these values did not achieve significance. The incidence of obesity ranged from 0-20% among the eleven matrilines studied, and several primary familial relationships were observed within the obese sample. Most obese females were from a high ranking matriline whereas only one of the obese males was high ranking at the time of the survey.(ABSTRACT TRUNCATED AT 250 WORDS)