Feed restriction and a diet's caloric value: The influence on the aerobic and anaerobic capacity of rats

We used 40 adult Wistar rats. The animals were divided into four groups: ad libitum commercial Purina？ diet (3028.0 Kcal/kg) (ALP), restricted commercial Purina？ diet (RAP), ad libitum semi-purified AIN-93 diet (3802.7 Kcal/kg) (ALD) and restricted semi-purified AIN-93 diet (RAD). The animals performed LM at the end of the experiment, 48 h before euthanasia. Comparisons between groups were performed by analysis of variance (p < 0,05).At the end of the experiment, the weights of the rats in the groups with the restricted diets were significantly lower than those in the groups with ad libitum diet intakes. In addition, the ALD group had higher amounts of adipose tissue. With respect to energetic substrates, the groups subjected to diet restriction had significantly higher levels of liver and muscle glycogen. There were no differences between the groups with respect to AT; however, the ALD group had lower lactatemia at the AT intensity and higher Tlim than the other groups.We conclude that dietary restriction induces changes in energetic substrates and that ad libitum intake of a semi-purified AIN-93 diet results in an increase in adipose tissue, likely reducing the density of the animals in water and favouring their performance during the swimming exercises.Several authors have studied the effects of caloric restriction on body composition and metabolic variables in both humans [1-3] and animals [4]. Reducing daily feed intake to 20 to 40% below ad libitum levels, or providing feed intermittently rather than continuously, has been found to significantly reduce the risk of chronic degenerative diseases such as cancer, type-II diabetes and kidney diseases, and to prolong the life span of laboratory rats and mice by 40% without causing malnutrition [4-7].However, excessive dietary restriction can lead to malnutrition and physiological changes that lead to decreases in sympathetic nervous system activity, changes in thyroid metabolism, reductions in insulin concentrations