We examined whether changes in gut hormone levels due to a single bout of 
aerobic exercise differ between obese young males and normal controls, and 
attempted to determine the involvement of hormonal changes during exercise in 
the regulation of energy balance (EB) in these obese subjects. Seven obese and 
seven age-matched subjects of normal weight participated in exercise and rest 
sessions. Subjects consumed a standardized breakfast that was followed by 
constant cycling exercise at 50% VO(2max) or rest for 60 min. At lunch, a test 
meal was presented, and energy intake (EI) and relative energy intake (REI) were 
calculated. Blood samples were obtained at 30 min intervals during both sessions 
for measurement of glucose, insulin, glucagon, ghrelin, peptide YY (PYY), and 
glucagon-like peptide-1 (GLP-1). Plasma levels of PYY and GLP-1 were increased 
by exercise, whereas plasma ghrelin levels were unaffected by exercise. The 
areas under the curve (AUC) of the time courses of PYY and GLP-1 levels did not 
significantly differ between the two groups. In contrast, EI and REI were 
decreased by exercise in both groups, and energy deficit was significantly 
larger in obese subjects than in normal controls. The present findings suggest 
that short-term EB during a single exercise session might be regulated not by 
increased amounts of these gut hormones per se.