What to Eat? When to Eat It?

• Position: DIGESTION

When one eats may be as important as what one eats. Research at the Weizmann Institute of Science, Rehovot, Israel, and Germany's Max Planck Institute of Biochemistry, which appeared in the Proceedings of the National Academy of Sciences, suggests that the cells' power plants--the mitochondria --are highly regulated by the body's biological, or circadian, clocks. This may help explain why people who sleep and eat out of phase with their circadian clocks are at higher risk of developing obesity, diabetes, and metabolic syndrome.

Gad Asher of Weizmann's Biomolecular Sciences Department, who led the study, explains that circadian clocks, which are found in living things from bacteria to flies and humans, control our rhythms of sleep, activity, eating, and metabolism. "In a sense, it's like a daily calendar, telling the body what to expect, so it can prepare for the future and operate optimally."

Adi Neufeld-Cohen of Asher's group, in collaboration with Maria S. Robles and Prof. Matthias Mann of the Max Planck Institute, looked for circadian changes in the mitochondria that, by creating peaks and dips in the cells' energy levels, also would help regulate their day-night cycles. The group identified and quantified hundreds of mitochondrial proteins, finding that the quantities of 40% peak once a day.

Further research identified the proteins making up the mitochondrial circadian clock that regulates these activities. Among the essential proteins the researchers uncovered was a key enzyme that determines the rate of sugar use for energy...