Morning is more insulin-sensitive than evening. A global trend in lifestyle changes is the shift and disruption of circadian rhythms, leading to a shift in the eating window and many other activities to late evening. Many beneficially use narrowing the eating window (the "time-restricted feeding" system, TRF), but use it as an excuse to skip breakfast and eat more at dinner.
However, it's essential to remember that our internal clocks and metabolism are closely linked, so detaching the eating window from daylight hours could be more beneficial. Whether we like it or not, our internal clocks prefer eating in the morning and during the day. That's why eTRF (Early Time-Restricted Feeding) shows excellent results.
As the saying goes, a banana in the morning and a banana in the evening are two different bananas: breakfast is gold, lunch is silver, and dinner is copper. Have breakfast like a king, share lunch with a friend, and give dinner to the enemy. Many others follow similar wisdom.
For example, let's understand how insulin sensitivity changes throughout the day. Insulin sensitivity in humans is regulated by circadian rhythms, decreasing in the evening and night. This process is linked to our central clock, the suprachiasmatic nucleus of the hypothalamus, and the liver, muscle, pancreas, and adipose tissue clocks. Insulin resistance is minimal in the morning and daytime, but sensitivity decreases in the evening for both fat and muscle tissues and the liver.
Regarding adipose tissue, its maximum insulin sensitivity occurs at noon, and the minimum is at midnight, decreasing by 54% from the maximum. The more you sleep and the less you stay inactive, the higher the insulin sensitivity of adipose tissue. The story is similar for the liver and muscles; their rhythms are exact and independent of glucose levels, insulin, exercise, or meal timing but depend on factors like cortisol levels.
Thus, our metabolism prefers to act according to circadian rhythms, and it's essential to respect this preference for our benefit. Let the majority of calories (80%) be consumed during breakfast and lunch, and these meals should be in the morning and day. Of course, you need to give a clear signal that morning has come! More light in the morning and during the day, more activity, and, consequently, less light in the evening.
In normal conditions, melatonin and insulin levels have reciprocal relationships. If you have evening exposure to light and food, your metabolism will undoubtedly face problems. High insulin levels can reduce melatonin levels and hinder its secretion. The reduction of melatonin and decreased sleep duration over time will reduce insulin sensitivity. Let food and insulin be during the day, and melatonin and dietary restraint be in the evening and night! Please don't mix them up!))
However, some carriers of rs10830963 (G) in the melatonin receptor gene MTNR1B find late or high-carbohydrate dinners particularly dangerous. Insulin is especially strongly blocked by melatonin, so late eating harms them more. Hence, an early and low-carbohydrate dinner is highly recommended.