Differential effect of common snack foods on caloric intake, growth and obesity in weanling male and female rats with hypothalamic obesity.

In order to see whether weanling normophagic rats with hypothalamic obesity (VMNL rats) become hyperphagic and more obese than when fed lab chow, and to see in addition whether there is a possible sex difference in whatever response is found, male and female VMNL rats were fed lab chow for 14 days after lesion production and then, for the following 42 days, they received Hostess HoHos, potato chips, marshmallows and french fries in addition to lab chow. At termination, body weights were similar among the groups, but VMNL rats were fatter and shorter than controls. Also, female VMNL rats were fatter and shorter than male VMNL rats and layed down more fat per unit of food energy. Total caloric intake was greater in controls than in VMNL rats and in males than in females. However, the females showed a decrease in intake and the males an increase over time. Males ate more lab chow and french fries than females. Lab chow was the only food that VMNL rats ate more of than controls. The VMNL rats ate less french fries, HoHos and potato chips than controls, but similar amounts of marshmallows. There was no sex difference in macronutrient intake and per cent macronutrient intake. Moreover, controls ate as much carbohydrate and less per cent carbohydrate than VMNL rats, more fat than VMNL rats, but normal per cent fat and normal protein and per cent protein. Sex X lesion interactions indicated that female VMNL rats ate more per cent carbohydrate than female controls and male VMNL rats, ate more protein than male controls. The greater degree of obesity in the females despite the lower caloric intake may be due to enhanced food energy utilization. The data also show that weanling VMNL rats do not exhibit the great preference for palatable diets that have been reported for mature rats with ventromedial hypothalamic area lesions and that the only sex difference in intake is with french fries, which have neither the highest fat nor the highest carbohydrate content of the foods tested.