Effect of a protein-sparing diet on responses to exercise in obese subjects

We have studied muscular work efficiency and VO2 peak in seven obese individuals (body mass index: 38.9 +/- 5.8 kg.m-2) before and after twelve days of a low-caloric diet (protein-sparing modified fast) providing about 2460 kJ/day. Respiratory gas exchanges were measured at rest and during an exercise protocol through a rubber mask connected to a pneumotachograph and a mass spectrometer. A significant reduction in body mass was observed with the diet therapy (109 +/- 12 vs 105 +/- 14 kg; p < 0.02). No significant differences were observed in VO2 peak (1.78 +/- 0.32 vs 1.88 +/- 0.43 l/min, p > 0.05) and work efficiency (26 +/- 5 vs 24 +/- 4%, p > 0.05), after the diet protocol. It is concluded that the low-caloric diet used had no effect on muscular work efficiency.