MICROSCOPY Vol.47▶No.2 2012
■Feature Article: Morphology of Biological Clocks

Circadian Rhythm and Ideal Eating Habits

Akiko Hirao and Shigenobu Shibata

Abstract: Animals including humans possess a circadian rhythm system which can control various physiological functions and also symptom expression rhythm of diseases. Chrono-pharmacological approaches have applied to reduce side-effect of drugs and to increase main-effect of drugs. Similar idea was applied to chrono-nutrition field for understanding between circadian rhythm and nutrition/feeding. Restricted feeding during daytime can entrain the circadian rhythm especially peripheral clocks, however importance of meal timing is still unknown. We found meal time after longer starvation is critical for entrainment under 2 meals per day schedule. In addition, food which can release insulin is better for entrainment; for example rapid digestible starch and fish oil containing food. Circadian clock controls absorption and metabolism process of nutrients and foods through the circadian function of transporters and fatty acids synthesis. Therefore the timing of meals affect the body weight gain and obesity. In mice experiments, ratio of high-fat food volume of breakfast: dinner was seat as 0:4, 1:3, 3:1, 4:0. Among 4 groups, breakfast: dinner (3:1) was most ideal feeding pattern for protection of obesity.  These findings strongly suggest that the timing of food intake becomes another important factor for health promotion.

Key words: Chrono-nutrition, biological clock, clock gene, life style rhythm, metabolic syndrome