The Renaissance Diet 2.0. Mike Israetel
outcomes. While 10% might seem inconsequential, consider that differences of much less than 10% in performance separate top athletes in the rankings. A difference of 1% or smaller in performance can determine whether you medal (or not) in the Olympics. Even in amateur sport competition, it is rare to see large differences in performance between athletes on the podium. A 10% difference per diet phase can also add up across years to make a more significant impact on long-term outcomes. For competitive athletes and fitness enthusiasts, especially those who are more experienced at training and dieting, meal timing is an important factor for optimizing progress. This chapter will cover the theoretical aspect of this principle. Practical application will be addressed in chapter 10.
Nutrient timing has six distinct components:
Meal number describes the number of meals an individual consumes per day. A meal is defined as any amount of food ingested in a single bolus (i.e., one ball of food and saliva). If you take a few bites of a sandwich at 1:00 pm and then take a few more at 1:30 pm, by sports nutrition standards, you have eaten two meals.
Meal spacing describes the timing of meals relative to each other. Choosing appropriate lengths of time between meals can depend on digestion time and hourly bodily needs. That being said, eating six, evenly sized, evenly spaced meals per day is not identical to eating three large and three small evenly spaced meals per day, even though by meal number and spacing they are the same; these differ in the third component: meal size.
Meal size is simply the amount of food eaten per meal and is measured in calories per meal.
Meal macros describe how much of each macronutrient is present in a meal and can differ between meals even when calories are held constant. For example, while two meals might each have 500 calories, one could contain 50 g of protein, 25 g of carbs, and 22 g of fat, and the other 25 g of protein, 50 g of carbs, and 22 g of fat. The size of each meals is the same in terms of calories, but they differ in macronutrient content.
Meal food composition describes the types of foods comprising the calories and macronutrients in each meal. The type of food within the meal can influence digestion rates, absorption rates, the satiety the meal provides, whether the meal causes gastrointestinal distress, and other factors worth consideration. Even when matched for calories and macronutrients, some food choices may be advantageous at certain times and not others. For instance, 30 g of protein is the same amount of protein whether it comes from a chicken breast or a whey protein shake, but one can be preferable to the other depending on when it is consumed. Whey protein digests very quickly and does not take up much stomach space, so it can be useful when trying to gain weight and feel full. In contrast, chicken digests slowly and has a higher volume, and therefore might be a better choice when you are feeling hungry and would like to feel satiated longer after a meal.
Meal timing around activity is the last of the nutrient timing components, but certainly not the least important. This component refers to structuring meals and macronutrients around training times to best support physique and performance outcomes. Of particular interest are the meals before, during, and immediately following training bouts.
NUTRIENT TIMING EFFECTS
Manipulation of the components of nutrient timing has well-studied effects that dictate the recommended optimal nutrient timing structure within diet design, which we will outline in the following sections. The various components of nutrient timing are very intertwined, however, and manipulation of one often affects the other. We will discuss the components according to effect and then summarize the resulting recommendations.
Meal Timing and Sizes for Satiety Levels and Adherence
According to the hierarchy of diet principles, poor nutrient timing schemes can result in 10% loss in performance and body composition results. Poor meal timing can also lead to issues with diet adherence, at further detriment to results. For example, if your muscle-gain diet requires 4,000+ calories per day, and you choose to eat two meals per day, those are 2,000-calorie meals. This might sound fun at the tail end of a fat-loss phase, but after several weeks of eating at a surplus, taking in meals of this size will become extremely difficult. Splitting the eating burden into four or five 800- to 1,000-calorie meals is much more sustainable. On the opposite end of the calorie spectrum, hypocaloric diets make people feel hungry. Outside of risking breaks in adherence (cheating on the diet), prolonged hunger can add to stress and fatigue levels that impact performance and decrease muscle retention. There are two kinds of timing extremes that needlessly increase hunger on a fat-loss diet. First is the very low frequency approach in which you spend most of your day starving and then indulge in a few large meals. Pulses of food-mediated pleasure can promote food craving and unhealthy relationships with food that last beyond the diet phase. On the other end, very high frequencies of feeding (10+ tiny meals per day) can result in never feeling that you have eaten a real meal and increase likelihood of off-diet eating.
The best recommendation for timing with relation to hunger and fullness is to eat four to eight evenly spaced meals of similar calorie content per day and avoid extremes outside of those boundaries. Biasing meal size a bit according to intermeal interval can be a good idea if schedules prevent evenly spaced meals (figure 4.1). Conveniently, these recommendations fit with protein frequency and proportion recommendations, which we will discuss shortly.
Figure 4.1 Point A marks your first meal of the day. Points B, C, and D mark when you would eat your second meal if (B) your first meal were smaller (absorbed in around 3 hours), (C) moderately sized (absorbed in around 5 hours), or (D) very large (absorbed in around 7 hours). In all these cases, a steady stream of nutrients is delivered across intermeal periods thanks to appropriate meal sizing.
Digestion Rates and Meal Timing
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