[24-hour energy metabolism in the human: circadian rhythm, relation to body weight and nutrition].

In 7 men with normal weight and 9 man with overweight and healthy metabolism the resting and fasting energy expenditure was indirectly calorimetrically pursued in the open system over 24 hours. The total energy expenditure over 24 hours revealed an ascertained dependence on body-weight and nutrition. The persons with overweight had a higher absolute energy expenditure, however, the activity of the energy metabolism of the body mass free from fat and the active body mass, respectively, decreased with increasing overweight. The resting and fasting energy expenditure showed in all measured parameters (oxygen consumption, respiratory quotient and nitrogen excretion in the urine) an ascertained daily periodicity (circadian rhythm), which was widely independent of body weight. Only the average daily level C0 (rhythm adjusted level) of the resting and fasting energy expenditure was positively correlated with the body weight and the food energy intake. A negative energy balance (reduction 1.2 MJ/d over 28 days) influenced only the total energy and substrate balance over 24 hours and the daily average level, respectively. The circadian conditions remained unchanged (Chossat's phenomenon). The variability in daily rhythm of the energy expenditure of nearly 25% of the daily average should be taken into consideration in the judgment of exogenically stimulated changes in the energy metabolism.