High protein vs high carbohydrate hypoenergetic diet in treatment of obese normoinsulinemic and hyperinsulinemic subjects

This study tests the hypothesis that hyperinsulinemic (HI) obese subjects respond differently from normoinsulinemics (NI) to changes in composition of hypoenergetic diets. Twenty-seven obese male subjects, 13 HI and 14 NI, were fed for 4 weeks either a high protein (HP) or a high carbohydrate (HC) hypoenergetic diet providing 80% of their resting energy expenditure (REE). On the HP diet weight loss was significantly higher in HI as compared to NI group. Alternatively, the HI group lost less weight than NI group on the HC diet. The HC diets resulted in a considerable and similar reduction in REE in both HI and NI groups as opposed to the HP diet, which maintained REE in both HI and NI. A higher decrease and normalization of fasting insulin levels was observed in the HI group on the HP as compared to HC diet. In conclusion, hyperinsulinemic, in contrast to normoinsulinemic obese subjects, seem to achieve better weight reduction, less decline in energy expenditure, and normalization of insulin levels on HP than isocaloric HC diet.