Appetite and blood glucose profiles in humans after glycogen-depleting exercise

Regulatory functions of glycogen stores and blood glucose on human appetite , particularly relating to exercise, are not fully understood. Ten men (age 20-31 yr) performed glycogen-depleting exercise in an evening, ate a low-c arbohydrate dinner, and stayed overnight in the laboratory. The next day, b lood glucose was monitored continuously for 517 +/- 23 (SE) min. Subjects h ad access to high-fat and high-carbohydrate foods after baseline glucose an d respiratory quotient were determined. In the afternoon, 1 h of moderate e xercise was performed. Baseline respiratory quotient was 0.748 +/- 0.008, p lasma free fatty acids were 677 +/- 123 mu mol/l, insulin was 4.8 +/- 0.5 m u U/ml, and leptin was 1.9 +/- 0.3 ng/ml. Postabsorptively, 8 of 10 meals w ere initiated during stability in blood glucose. Postprandially, the associ ation between meal initiation and blood glucose declines became significant (chi(2) = 7.82). During moderate exercise, blood glucose initially decreas ed but recovered before completion. When the glycogen buffer is depleted, m eal initiation can occur during blood glucose stability; the relationship b etween blood glucose declines and meal initiation reestablishes with refeed ing.