The effect of feeding a highly-palatable and varied diet on growth and body composition was assessed in male rats, some of which had undergone a period of undernutrition early in their development. 2. Undernutrition during gestation had no effects on weight, length or fat content of offspring in adulthood. Rats underfed during the first 3 weeks of postnatal life were shorter, lighter and more lean as adults than controls which had been well nourished through life. 3. Feeding the palatable diet from weaning led to increases in length and fat-free mass, and to comparable extents of obesity in all groups, irrespective of whether they had suffered either period of undernutrition. Access of palatable food for 30 d in adulthood also led to obesity, but to increases in length and fat-free mass in only the groups undernourished during suckling. 4. Withdrawal of the palatable diet led to some initial weight loss in all groups, irrespective of whether they had been undernourished during development; and 100 d following the replacement of the palatable with stock diet, there were no longer differences in weight between groups which had received palatable food, and those given stock diet throughout. 5. Nevertheless, those rats which had been undernourished during the suckling period and subsequently fed on the palatable diet still showed increased length and fat-free mass relative to their controls fed on the stock diet throughout. 6. All groups which had received the palatable diet, whether from weaning or as adults, and irrespective of early nutrition, were significantly less fat 100 d after its withdrawal than were those rats fed on the stock diet throughout life.
