Laboratory rats, when kept in conditions regarded as “standard”, are physically inactive, do not have proper environmental stimulation and have free access to food, which can lead to metabolic syndrome and fat accumulation in the liver. This study aimed to analyse the susceptibility of “control animals”, which have free access to food, to metabolic syndrome and fat accumulation in the liver compared to animals that were subjected to food restriction. Ninety-day-old Wistar rats were divided into two groups, fed ad libitum (free access to food) and food restricted (60% of the amount of food consumed by the ad libitum group), according to a protocol of alimentation for four weeks. To analyse the effects of food restriction on the nutritional status, serum albumin and total protein levels were analysed and showed no differences between groups, which indicated an absence of malnutrition. The retroperitoneal, subcutaneous and mesenteric fat tissues were weighed, and it was found that the mesenteric fat tissue showed a greater reduction from the food restriction. There was no difference in the insulin sensitivity and the fat accumulation in the liver between groups. However, it was shown that for every 1% decrease in weight due to the food restriction, insulin sensitivity increased by 0.67% and hepatic fat decreased. Therefore, we can conclude that caloric restriction leads to weight loss. Although no significant differences in insulin sensitivity and hepatic fat content existed between the groups at the end of the experiment, weight loss modulated these variables.