Metabolic effects and body fat mass changes in obese subjects on a very-low-calorie diet with and without intensive...

During 4 weeks, 40 obese subjects (body mass index 30-45 W/H2) were treated with a 300-kcal mixed diet alone or in combination with exercise training on a bicycle ergometer in a metabolic ward. Exercise had a minor effect on body weight, reflected by an additional fat loss of 1.7 kg (expected loss: 4.0 kg). Hyperinsulinemia was improved by diet and normalized by diet combined with exercise; a similar effect was observed regarding C-peptide levels. Plasma concentrations of epinephrine and norepinephrine decreased in both groups. At maximal work, norepinephrine levels were higher in the group with exercise. Free fatty acids and free glycerol increased at rest as well as during exercise in subjects on both regimens, the difference being more pronounced in the exercise group. Enhanced oxidation of fat was substantiated by lower respiratory quotients during endurance exercise. Working capacity increased and blood pressure decreased considerably as a consequence of physical training. It is concluded that exercise training in addition to a hypocaloric diet lowers body weight and body fat, although to a lower degree than expected. During and following bouts of exercise, fat mobilization and oxidation is enhanced, but these effects are probably counteracted at rest. On the other hand, the diet-induced deterioration of physical performance is overcompensated.