Intrauterine food restriction is associated with obesity in young rats.

The purpose of this study was to examine the effects of malnutrition during the first 2 wk of intrauterine life on the regulation of energy metabolism and the activity of brown adipose tissue in rats at 53 d of age. Intrauterine malnutrition led to an imbalance in the control of energy metabolism that was influenced by gender. In males, the intrauterine malnutrition resulted in impairment of normal weight gain and fat deposition during 1 to 53 d of age, in association with low plasma total triiodothyronine concentration, in spite of normal food intake. In contrast, the intrauterine malnutrition in females led to a marked fat accumulation by 53 d of age with normal food intake, and decreased brown adipose tissue weight, protein content and cytochrome c oxidase activity, indicating a lower sympathetic activity. These data indicate that nutrient availability during the first 2 wk of intrauterine life determines the control of energy utilization during early post-weaning period.