Current sports nutrition guidelines recommend distributing protein intake in multiple equal meals throughout the day (1). This concept of protein distribution is primarily based on studies suggesting that only a limited amount of protein ingested in a single meal can effectively be used for muscle protein synthesis (the process that allows muscle to recover and adapt to training). It was believed that there is a linear increase in muscle protein synthesis up to doses of approximately 20 g protein, with a relatively small 10-20% further benefit when the dose is further increased to 40 g (2,3). Therefore, it was thought that it’s better to have multiple smaller meals throughout the day when compared to consuming the same amount of protein in a few bigger meals.
Does protein distribution actually impact muscle growth?
In contrast to single meal studies, most long-term studies failed to find any benefit of protein distribution. Even studies on intermittent fasting/time-restricted findings did not observe a detrimental effect on lean body mass (4,5). In such diets, all food is consumed in a relatively short feeding window during the day (for example, in 8 hours). Such intake pattern should be very suboptimal for muscle mass, according to the concept of protein distribution.
We speculated that the previous single meal studies comparing different amounts of protein had a limitation: they only measured muscle protein synthesis for 4-6 hours after the meal. But is this fair? Greater amounts of protein may require a more extended period before they are fully digested, absorbed, and becomes available for muscle tissue. Therefore, we designed a study to test this hypothesis.
Rethinking protein intake needs: BBQ study findings
We performed a single-meal study with 0, 25 and 100 g protein immediately after whole-body resistance exercise in healthy young adults over a 12-h measuring period (6). We named it the BBQ study, because we could eat about 100 g of protein during a BBQ before we would need to force feed ourselves.
The main findings of the study were:
While the 25 g dose was already almost entirely digested and absorbed after 6 hours, the 100 g protein was still being digested at the end of the 12 hours.
The 100 g dose resulted in 19% higher muscle protein synthesis rates over the first 4 hours when compared to the 25 g dose. This is in line with earlier dose-response studies that typically observed that doses greater than 20 g result in a 10-20% higher rate over such time period.
The 100 g dose resulted in 30% higher muscle protein synthesis rates over the entire 12 hour period when compared to the 25 dose. Combined with the previous point, this shows that while a dose of >25 g protein already has a greater anabolic effect early on, the main advantage happens in the later stage (when the moderate dose “runs out of steam”).
Another important observation was the modest increase in amino acid oxidation (burning amino acids from protein as fuel, essentially wasting them instead of using them as building blocks). Previous studies suggested that most of the protein consumed in excess of a 20 g dose is oxidized. However, this was simply based on the fact they observed a statically significant increase in amino acid oxidation. When we calculated how this “significant increase” translated to actual amounts of protein, it showed that for every additional gram of protein ingested, less than 15% is oxidized. In other words, that means that for every additional gram of protein you consume, at least 85% is not oxidized and available to be used as a building block.
What are the implications for protein intake?
Evidence for protein distribution was almost entirely based on acute studies suggesting a plateau in muscle protein synthesis and that protein consumed in excess of a 20 g would be mostly oxidized. This evidence now falls away.
Therefore, the current evidence in favor of protein distribution is fragile. If total daily protein intake is sufficiently high, protein distribution likely has little to no further benefits. Thus, this means that athletes could be more flexible with their protein intake. However, it would be premature to claim that protein distribution has NO added benefit at all (we simply don’t know yet). It is not much effort to have at least a reasonable protein distribution. However, it is probably not worth it to stress about the details.
A practical protein approach:
If your next meal is in the next 5 hours, consume at least 20 g.
If your next meal is not in the next 5 h, it is recommended to consume at least 40 g.
Even easier: just focus on your total daily protein intake. That will likely give you most or even all the benefits without much stress.
Summary
You can consume a large amount of protein in a single meal without it going to waste. Total protein intake during a day is most important, how you divide that throughout the day likely has minimal impact.
Reference
Phillips SM, Van Loon LJ. Dietary protein for athletes: from requirements to optimum adaptation. J Sports Sci. 2011;29 Suppl 1:S29-38.
Moore DR, Robinson MJ, Fry JL, Tang JE, Glover EI, Wilkinson SB, Prior T, Tarnopolsky MA, Phillips SM. Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men. Am J Clin Nutr. 2009 Jan;89(1):161-8.
Macnaughton LS, Wardle SL, Witard OC, McGlory C, Hamilton DL, Jeromson S, Lawrence CE, Wallis GA, Tipton KD. The response of muscle protein synthesis following whole-body resistance exercise is greater following 40 g than 20 g of ingested whey protein. Physiol Rep. 2016 Aug;4(15):e12893.
Tinsley GM, Moore ML, Graybeal AJ, Paoli A, Kim Y, Gonzales JU, Harry JR, VanDusseldorp TA, Kennedy DN, Cruz MR. Time-restricted feeding plus resistance training in active females: a randomized trial. Am J Clin Nutr. 2019 Sep 1;110(3):628-640.
Trepanowski JF, Kroeger CM, Barnosky A, Klempel MC, Bhutani S, Hoddy KK, Gabel K, Freels S, Rigdon J, Rood J, Ravussin E, Varady KA. Effect of Alternate-Day Fasting on Weight Loss, Weight Maintenance, and Cardioprotection Among Metabolically Healthy Obese Adults: A Randomized Clinical Trial. JAMA Intern Med. 2017 Jul 1;177(7):930-938.
