Nutrition Noteworthy

Possible circadian cyclicity in both feeding behavior and in metabolic responses to food may contribute to the purported tendency toward weight gain of individuals who eat primarily at night. Investigation into both physiological and metabolic correlates to feeding and energy utilization revealed that leptin, a satiety hormone, is not regulated in circadian fashion. Diet-induced thermogenesis showed a strong circadian rhythm, with increased thermogenesis in the day. Insulin sensitivity and plasma glucose levels, as well as growth hormone levels, also have circadian rhythms which may be modified slightly but not appreciably disrupted by sleep and activity pattern changes.