20 fa/fa Zucker rats were submitted to a normalization of their food-intake energy level by pair-feeding using control Fa/- rats, for 4 weeks. Two diets were tested. The first was a starch-based diet (A) (66% starch w/w) and the second a sucrose-based diet (S) (66% sucrose w/w). The food-intake levels and the efficiency of storage of energy were thus comparable for the two diets. Though the fa/fa hyperinsulinemia decreased for the 4 weeks of experiment and was comparable with the (S) and (A) diets, the hypertriglyceridemia was lower with the (S) diet than that for the (A) diet. This could be in relation to the increased post-heparin lipase activity in the (S) diet, compared to the (A) diet.