Weight reduction in young obese children. I. Effects on adipose tissue cellularity and metabolism.

A 10-year longitudinal study was conducted on 16 prepubescent youngsters who had undergone successful weight reduction. Their ages ranged from 2 to 10 years when the study began. In all subjects, weight reduction proceeded only by a decrease in adipose cell size (from 0.62 +/- 0.02 to 0.46 +/- 0.02 micrograms lipid per cell) and resulted in a corresponding 33% decrease (from 177 +/- 6 to 144 +/- 5%) in percent ideal body weights. Cell numbers did not change appreciably during the period of weight loss (29.4 +/- 2.6 versus 28.7 +/- 2.3 x 10(9) total adipocytes). Three years after the start of the study, 14 of 20 youngsters had maintained their reduced percent ideal body weights, including eight who remained below 130% ideal body weight. Ten years later, only four remained below 130% ideal body weight. All four children had total adipose cell numbers below 20 x 10(9) total adipocytes at the start of the weight reduction program, a value below the lower limit for adult normal weight subjects. Thirteen other children have maintained or decreased their initial percent ideal weights. The remaining nine youngsters have further increased their percent ideal body weights. In vitro metabolic studies of the patient's adipocytes revealed a greater than 50% depression of epinephrine-stimulated lipolysis pre- and immediately postweight reduction; this decrease persisted for the entire period of study, irrespective of the maintenance of a normal percent ideal body weight. At the same time, normal 150% increases in the in vitro production of 14CO2 from [1-14C]glucose in the presence of insulin occurred.