Regional differences in the lipolytic response of the subcutaneous fat depots to prolonged exercise and severe energy deficiency.

After five days of almost continuous strenuous combat exercise and energy deficiency, 12 well-trained young men had a mean body fat loss of 2.7 kg and the average fat cell size was reduced from 0.34 microgram to 0.24 microgram. No significant changes were found in the total number of fat cells. For the group as a whole, the decrease in fat cell size was most pronounced in the gluteal subcutaneous region, followed by the abdominal region. No significant decrease in fat cell size was encountered in tissue samples from the femoral site. Before the course, and on the last day, the subjects accomplished a short-term bicycle exercise at 50% of the individual's VO2. On day 5, positive correlations were found between the fat cell weights estimated in the gluteal tissue samples and the pre-exercise free fatty acid (FFA) levels (r = 0.87, p less than 0.01), and also with the plasma free glycerol obtained five minutes after the bicycle exercise (r = 0.93, p less than 0.001). These correlations were not apparent in the control experiment performed before the course. Further, no such relationship was found between the plasma metabolites and the fat cell size of the other body sites investigated. This finding may indicate that gluteal fat deposits are more important for energy provision than abdominal and, especially, femoral deposits.