Exhaustive graded exercise leads to changes of hormones, carbohydrate, and lipid metabolism in normal controls and obese patients after prolonged starvation. Concomitant with a large increase of plasma catecholamines, insulin concentration is reduced and blood glucose levels slowly increase. More glucose is made available by glycogenolysis and gluconeogenesis than can be oxidized in the mitochondria. Lactate associated metabolic acidosis appears. Starving obese patients in the basal state have reduced blood glucose concentrations, but their initial values for free glycerol, free fatty acids, and ketone bodies are much higher than in normal controls. This is caused by the starvation induced lipolysis. With exhaustive exercise adrenaline, noradrenaline, and free glycerol increase. In contrast, free fatty acids and ketone bodies decrease, because they are consumed as fuel. Prolonged starvation changes basal values of hormones and metabolites, but it does not change the quality of exercise-induced shifts in these values when compared with those of the normal controls.