Circadian rhythms and food: why the same plate costs more in the evening

The main clock in the brain is set by light. But the liver, pancreas, adipose tissue, and muscles have their own clocks—and they are set by food. When you eat at 22, the liver thinks it is daytime while the brain thinks it is night. This mismatch has been studied in shift workers: the same diet, but worse weight, blood sugar, and blood pressure. The same happens to those who have dinner at 21-22 every day.

Dinner before 19 and breakfast after 9 make 14 hours during which the liver and pancreas sleep along with the brain. Studies of early time-restricted eating: with the same calories, eating from 8 to 17 versus 12-21 resulted in lower insulin, blood pressure, and appetite. So for weight, it is important not only to have «16 hours», but also which hours they are: an earlier window works better than a later one. The foundation is intermittent fasting.

Half an hour of daylight during the first hour after waking is the strongest signal for the clock, stronger than food. It raises cortisol in the morning, where it belongs, and starts the countdown to evening melatonin. In the evening, the opposite is true: bright light and screens tell the brain «day», and melatonin is delayed by one or two hours. Warm, dim light after 21, and you fall asleep earlier without effort. Protocol — how to fall asleep.