Bodybuilders are reported to have a mean intake of six meals a day [66
]; however, there are no studies looking specifically at what might be an optimal meal frequency for this population [65
]. This high frequency of meals is based on the belief of a greater state of anabolism and even a better use of nutrients during the day, which could translate into an improvement in body composition.
The concept of timing protein intake to maximize hypertrophy spans a number of dosing strategies. The first to appear in the literature was the consumption of protein in close proximity to resistance training. Peak MPS rates are higher in this period when protein is consumed; thus, this strategy is proposed to improve the efficiency of skeletal muscle repair and remodeling [31
]. Additionally, due to the “muscle full effect”, whereby further provision of protein fails to increase MPS until sufficient time has passed, evenly spreading protein intake between multiple meals is another strategy designed to maximize total daily MPS [67
]. Finally, pre-bed consumption of slow-digesting protein (such as casein) to prevent extended catabolic periods during sleep is the most recently proposed strategy to improve net daily protein balance [68
]. Each of these three strategies will be discussed in turn.
6.1. Protein Dosage
The post-training period permits a higher MPS peak when protein is consumed [31
] and to reach peak MPS, an adequate “threshold” leucine dose may be needed [32
]. Several studies have examined the protein dosage required to maximize MPS after training [69
]. In one, 0, 5, 10, 20 or 40 g of whole egg protein was consumed following lower-body resistance exercise with 20 g maximally stimulating MPS [69
]. Similar results were also seen in another study, where 20 g whey was sufficient to maximally stimulate post-absorptive rates of MPS both at rest and after unilateral leg work at 80% of 1 RM [70
]. Further, 40 g of whey produced no additional increases of MPS in this study and lead to oxidation and urea production.
However, a recent study found that when performing whole-body resistance exercise at 75% of 1 RM, 40 g of whey produced a significantly higher MPS response compared to 20 g [71
]. Therefore, there is a relationship between the volume of muscle tissue that is damaged and stimulated, and the appropriate intake of protein. Interestingly, authors of a 2013 meta-analysis noted that despite short term tracer studies showing greater MPS responses when protein was consumed in the “window of opportunity” post-training, in longitudinal training studies no significant effect on hypertrophy was found when controlling for total daily protein intake regardless of whether protein was consumed within the window, or outside it [72
6.2. Nutrient Timing
Similarly, researchers in a short term tracer study investigating protein dosing over the course of 12 hours reported a greater MPS area under the curve when four 20 g whey protein doses were consumed every three hours compared to two 40 g doses six hours apart and eight 10 g doses every hour and a half [73
]. In theory, given the threshold past which additional protein consumed in a single sitting does not further contribute to MPS [69
], and due to the post-prandial “refractory period” during which MPS cannot be maximally stimulated again [67
], one would conclude that a bodybuilder should reach—but not exceed—this threshold dose every few hours to maximize long term hypertrophy. However, authors of a 2018 systematic review on protein supplements including 34 randomized controlled trials, reported similar lean mass gains among groups using a with-meal (resulting in fewer protein servings of a high magnitude) and between-meal (resulting in more protein servings of a moderate magnitude) dosing schedule [74
Intriguingly, data examining night-time protein feedings display a similar disconnect between short term mechanistic studies and long-term training interventions. In 2012, the first research examining the acute response to night-time casein feeding was carried out [68
]. In it, the authors reported 40 g of casein consumed before bed was digested, absorbed, and stimulated MPS and improved whole-body protein balance during the overnight period to a greater degree than placebo. Additional acute studies were published in the years following which confirmed [75
] and also reconfirmed these findings in an older population [76
]. In 2015, authors of the first longitudinal study reported enhanced strength and hypertrophy in a night-time protein-supplemented group compared to a placebo group [77
However, total daily protein was not matched, as the night-time protein group consumed 1.9 g/kg/day while the placebo group only consumed 1.3 g/kg. Importantly, in both of the only protein matched longitudinal studies comparing night-time casein supplementation to earlier-supplemented groups, no significant differences in FFM gains were reported between groups [78
]. Thus, the question is the same for each distribution strategy, why are there repeated disconnects between short term mechanistic studies of MPS and long-term research examining actual hypertrophy? The answer may lie in the methods used in MPS studies as participants are fasted, provided only protein powder in isolation, often given whey (which is digested very quickly) and observed for short periods. These lab settings result in different digestion time courses and amino acid kinetics than occur in the “real world”. Specifically, in these lab conditions baseline levels of amino acids in the body are lower than normal, and digestion and subsequent delivery of amino acids to muscle is faster.
In free-living conditions, protein is consumed primarily from whole food sources, multiple times per day, and in conjunction with other foods, all of which delays gastric emptying. For these reasons, amino acids are titrated into the bloodstream in a slower, more consistent manner; thus, there is almost always a readily available supply under normal conditions [80
]. Therefore, the effectiveness of the “anabolic window” and even protein distribution strategies might not translate to practice. Additionally, lab-specific limitations extend to night-time feeding studies as well. Consider for example, that 26 g of protein from lean steak results in a sustained elevation in MPS lasting at least six hours (the entire time period studied) [81
Furthermore, 26 g is only ~37% the protein dose contained on average in an American dinner [82
], which would take longer to digest due to the larger serving of protein, and the addition of fiber, lipids and other nutrients which would further delay digestion [80
]. Therefore, the typical final meal may already fulfil the intended purpose of a casein shake. With that said, despite these disconnects between MPS and body composition outcomes, there is certainly no harm from attempting these strategies, especially if implemented in a pragmatic manner that doesn’t introduce additional logistical strain on one’s daily schedule.
Therefore, it might be prudent to recommend bodybuilders to divide their daily intake of 1.6–2.2 g/kg of protein per day into multiple meals each containing ~0.40–0.55 g/kg [80
] and ensure that one of these meals occurs within 1–2 hours before or after training, and one feeding consisting of a non-whey protein source is consumed 1–2 hours prior to sleep. For example, a 90 kg bodybuilder might consume 40–50 g of protein at 8–9 am for breakfast, train at 11 am, have 40–50 g of protein at 12–1 pm for lunch/post-training, 40–50 g of protein at dinner between 5–6 pm, and then a final meal of 40–50 g of non-whey protein at 9–10 pm before heading to bed by 11 pm.
Carbohydrates consumed peri-workout is often a strategy utilized by athletes to improve performance in high intensity exercises. Complete glycogen resynthesis can be achieved within 24 hours following a glycogen depleting training bout if sufficient amounts of carbohydrate are consumed [83
]. However, only 24–40% of muscle glycogen is depleted following resistance exercise [59
]. Therefore, an amount of ≥3–5 g/kg carbohydrates per day would most likely be enough for glycogen resynthesis. This high daily carbohydrate intake likely also reduces the impact of pre-workout carbohydrate timing on exercise performance.
Consuming carbohydrates with protein post-workout is often claimed to have a an anabolic effect due to the secretion of insulin. Although insulin has been shown to have anabolic effects [84
], at physiological levels its release has little impact on post-exercise anabolism [85
]. Further, several studies have shown no further effects on muscle protein synthesis post-exercise when carbohydrates are combined with amino acids [86
In addition to bodybuilders lacking the need to emphasize glycogen replenishment, protein enhances post workout MPS to maximal levels even without the addition of carbohydrate [86
]. While there is certainly no harm in post-workout carbohydrate consumption, doing so is unlikely to enhance long term hypertrophy as discussed in prior reviews [1
]. Therefore, it may be best to focus on consumption of adequate daily carbohydrate and base carbohydrate distribution around the workout on personal preference.