OVERFEEDING IN IDENTICAL-TWINS - 5-YEAR POSTOVERFEEDING RESULTS

From a total of 12 pairs of young male identical twins who were overfe d by an estimated 84,000 kcal over a period of 100 days, several pairs (eight to 11, depending on variables) were remeasured for body weight , body composition with the underwater weighing technique, regional fa t distribution from skinfolds, girths, computed tomography (CT) fat ar eas in the abdominal region, and fasting plasma glucose, insulin, tota l cholesterol, high-density lipoprotein (HDL) cholesterol, and triglyc erides 4 months and 5 years after completion of the overfeeding protoc ol. At 4 months, the twins had lost approximately 7 of 8 kg that they had gained with overfeeding. However, 5 years later, body weight had i ncreased by 5 kg over the preoverfeeding level. Fluctuations in fat ma ss were greater than those in fat free mass. The younger twins gained approximately twice as much as the older twins in the late recovery pe riod, a difference attributed to the late phase of growth ire body mas s in the former. Upper-body fat was reduced at 4 months of follow-up s tudy, bur was increased ire the late recovery phase. All blood values were normalized in the postoverfeeding periods. A within pair resembla nce was generally observed for the changes noted in the recovery perio ds, but it was more striking when variations between preoverfeeding an d 4-month or 5-year values were considered,. We conclude from these ob servations that there were no persistent effects of exposure to the ov erfeeding protocol over the expected age-associated increases in body mass, body fat, upper-body fat, abdominal visceral fat (AVF), and meta bolic variables predictive of risk for common diseases in individuals of normal body weight and With no family history of obesity. The intra pair resemblance suggests that the genotype contributes to the alterat ions observed in the recovery from overfeeding and in the age associat ed changes. Copyright (C) 1996 by W.B. Saunders Company