Energy expenditure during normo- and overfeeding in peripubertal children of lean and obese Pima Indians.

We investigated the hypothesis that peripubertal children born to obese parents have a lower 24-h energy expenditure during "weight maintenance" and/or in response to overfeeding when compared with children born to normal-weight parents. Sixteen Southwestern American Indians (12.4 +/- 1.4 yr, 55.5 +/- 14.1 kg, 30 +/- 8% body fat), eight offspring from obese parents [body mass index (BMI) = 40 +/- 6 kg/m2], and eight offspring from thin parents (BMI = 24 +/- 3 kg/m2) were admitted for 8 days to our metabolic ward. The 24-h energy expenditure was measured under eucaloric conditions and on the 3rd day of progressive overfeeding of a mixed diet, i.e., 150, 200, and 200% of weight maintenance on day 1, 2, and 3 of overfeeding. At base line, offspring of obese parents were heavier (64 +/- 15 vs. 47 +/- 6 kg, P less than 0.05) and tended to be fatter (34 +/- 8 vs. 26 +/- 9% body fat, P = 0.07), with a higher absolute fat mass (22 +/- 9 vs. 13 +/- 4 kg body fat, P less than 0.05) when compared with offspring of thin parents. During both normo- and over-feeding, the larger part of the variance in 24-h energy expenditure in the conditions of a respiratory chamber was accounted for by differences in fat-free body mass (54 and 68%, respectively), whereas differences in the level of spontaneous physical activity accounted for another 19 and 21%.