Effect of scheduling of meal times on the circadian rhythm of energy expenditure].

Abstract 15 obese subjects were studied under different meal-timing schedules in order to see if meal-timing could affect the circadian pattern of energy expenditure. 4 subjects were given one meal (700 Kcal.) a day at h 10 in the morning (for 3 days) or at h 18 in the afternoon (for another 3 days). 4 subjects were given 3 meals (240 Kcal. each) at h 10, h14, h 18 for 3 days. 7 subjects were kept absolutely fasting for 36 hours. O2 consumption and CO2 production were measured minute by minute for 30' every 4 hours by means of a gas-analyser Mijnardht Oxicon II. Urine Samples were taken every 4 hours for urinary nitrogen determination. Energy expenditure was calculated according to Consolation's formula. Cosinor test was used to detect circadian rhythms. A statistically significative circadian rhythm of energy expenditure could be detected in all the protocols. The observed small differences among acrophases and the overlapping of confidence's ellipses allow to conclude that meal-timing doesn't affect the circadian rhythm of energy expenditure and suggest that this rhythm can be considered endogenous.