Читать книгу The Renaissance Diet 2.0 - Mike Israetel, James Hoffmann - Страница 73

The GI tract takes longer to digest larger amounts of food, but only to a certain extent. This is one of the reasons that four meals per day is the lowest recommended frequency. Three or fewer meals per day on a hypocaloric diet might seem logical for fat loss. The trouble is that this meal structure leaves stretches of time between meals when food is fully absorbed, but no new nutrients are coming in. This is a problem for muscle retention. During the time between meals when you have digested and used the previous meal’s protein, your body will begin to break down muscle tissue for amino acids. If you instead ate the same number of calories distributed over six evenly sized meals, fat would still be lost (because of the hypocaloric aspect), but due to the continuous input of amino acids, muscle would be spared.

Meal composition can also alter digestion time, playing an important role in meal-timing choices. Different protein and carb sources digest and absorb at different rates. For example, while whey protein digests and absorbs within the hour if taken alone in small doses, a chicken breast of equivalent protein content can take two to four hours to absorb. Casein protein can take longer than seven hours to fully absorb. Similarly, carb sources like dextrose powder (pure glucose) are absorbed in minutes, whole-grain breads in several hours, and some fruits take even longer.

Fats slow the digestion of other nutrients and decrease their rate of delivery to muscles. If you consume a large amount of fat but very little protein in a meal, protein delivery to muscles will be delayed. Higher fat meals are best eaten with additional protein so that per-hour amino acid availability is sufficient during the lengthened digestion and absorption period.

You can choose nutrient sources to fit your schedule. If you eat four times a day, your typical food sources should be moderately or slowly digesting protein and carbs that will gradually release nutrients into your bloodstream for the entire meal interval (figure 4.2). Since added fats slow down the digestion of all nutrients, they can make these differences moot, but individuals on lower fat diets should pay more careful attention to meal composition.

Figure 4.2 Graph A depicts the absorption time of a meal made up of fast-digesting carbs and proteins that is digested and absorbed prior to the next meal, a poor timing strategy. Graph B depicts the absorption time of another meal with the same macro content as graph A, but composed of slower digesting carbs and proteins that provide nutrients for the entire intermeal interval, a better timing strategy.