During the first stages of life a balanced diet is fundamental for a correct growth. One of the systems most affected by an incorrect food intake is the muscle-skeletal system, whose degree of development is important in determining the effect of malnutrition (Ardawi et al., 1989). Thus, the aim of this work was to observe the effects of an unbalanced diet on muscle metabolic activity in relation to muscle enzyme activity.

Two different diets were assayed in male albino rats Wistar. 5 rats (SD rats) were fed with a standard laboratory diet (18% protein, 3% fat and 77% carbohydrate) and another 5 rats (HD rats) were fed with hypercaloric peanuts diet (25% protein, 50% fat and 11% carbohydrate) from weaning (21 days) to the age of 50 days. The rats were weighed every three days throughout the experiment. On Day 50 the animals were killed by the administration of CO2 and the muscles (gluteus and flexor digitorum superficialis) of both SD and HD rats were rapidly dissected. Maximal enzyme activities of hexokinase, citrate syntase, 3-hydroxyacil-Coa dehydrogenase, phosphorilase and lactate dehydrogenase were measured (Essén et al., 1980).

The body weight gain in HD rats (67% lower) was markedly lesser than that of SD rats (p<0.001). However, the enzyme activity was not influenced by the diet and no differences between muscles were observed. This indicates that a hypercaloric diet is not adequate for growth because it affects to the body weight, although the general muscle metabolic profile does not change with the diet.