Protein Recommendations

Following protein digestion, the constituent amino acids pass through the intestinal wall to be transported to the liver (via the Hepatic portal vein). Amino acids not used by the liver then enter the bloodstream, ultimately to be utilised by muscle and other target tissue. Muscle proteins are continually “turning over”. In other words, they are broken down into aminos and re-synthesised. The difference between (the anabolic) muscle synthesis and (catabolic) muscle breakdown is known as the Net Muscle Protein Balance. If it’s positive, then we accrue muscle. And if it’s negative, muscle atrophy will occur. With that in mind, how much protein do we actually need to tip the balance in our favour?

To answer that we need to establish how much protein we can effectively use. That will depend on training goal. Assuming that improving body composition (the ratio of muscle to fat) is the desired outcome, a study published in the Journal of Sports Sciences recommends a generous protein intake between 1.8-2.7g per kg of bodyweight when dieting (Phillips and Van Loon, 2011). This figure should be scaled upwards with the severity of calorie deficit and leanness of the individual.

Once daily protein targets have been established, recommendations should be in place for how much protein can be used in a single meal. The “muscle full” theory offers a blanket recommendation of 20-25g of protein per meal, regardless of the size of the individual. The misconception being that any protein exceeding this limit is burned as fuel or excreted as urea. However, a recent study published in the Journal of the International Society of Sport Nutrition by fellow ACA contributor Brad Schoenfeld is able to provide more individualised recommendations. Schoenfeld et al. (2018) recommend 0.4-0.55g per kg of bodyweight per meal across >4 meals. This was supported by previous research by Moore et al. (2014), who also added that older participants might require as much as 0.6g/kg/bodyweight/meal to achieve the same anabolic response.

A key factor influencing the upper anabolic threshold for per-meal protein intake is the rate of protein absorption. “Fast-acting” whey is rapidly absorbed at 10g per hour (Bilsborough and Mann, 2006), taking a mere two-hours for a protein shake to be fully ingested. On the other hand, protein sources such as eggs have a far slower absorption rate at just 3g/hour. So it would take almost seven-hours to absorb the equivalent 20g protein from an omelet – resulting in greater overall protein uptake. Whole-food meals containing a mix of protein, carbohydrate and fat will delay protein absorption when compared to protein shakes. Aminos will be released into circulation at a slower rate, meaning a larger volume of protein can be consumed and efficiently used in a single meal.

Written by ACA Contributor Jason Jackson

Jason’s career began in 2008 when he joined an experienced personal training team at a Virgin Active health club in Northwest London. By 2012 Jason had become an accredited strength and conditioning coach, giving him the necessary credentials to work with professional athletes. Jason spent a season at Brentford Football Club, before a further two-years conducting research at the Saracens’ human performance lab.

In 2017 Jason became a Master of Science in sport nutrition. For his thesis, Jason spent two-years conducting a systematic review of over 100 testosterone studies. In addition to the well-documented physical effects on muscle mass and body fat, Jason examined testosterone’s significant influence on cognitive performance and wellbeing. Jason then integrated his findings into a unified strategy to successfully reverse the age-related decline in testosterone.

Jason is a registered nutritionist with SENr, the performance-orientated division of the British Dietetic Association. In his role as educator, Jason delivers seminars on performance and wellbeing at corporate accounts across the City of London. Clients include All Saints, RBS and exclusive high-end members club The Ned. The number one trainer in Virgin Active’s 20-year history, Jason wrote the book (literally) on nutrition strategy for the company.

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REFERENCES

1. Bilsborough, S. and Mann, N., 2006. A review of issues of dietary protein intake in humans. International journal of sport nutrition and exercise metabolism, 16(2), pp.129-152.

2. Moore, D.R., Churchward-Venne, T.A., Witard, O., Breen, L., Burd, N.A., Tipton, K.D. and Phillips, S.M., 2014. Protein ingestion to stimulate myofibrillar protein synthesis requires greater relative protein intakes in healthy older versus younger men.Journals of Gerontology Series A: Biomedical Sciences and Medical Sciences, 70(1), pp.57-62.

3. Phillips, S.M. and Van Loon, L.J., 2011. Dietary protein for athletes: from requirements to optimum adaptation.Journal of sports sciences, 29(sup1), pp.S29-S38.

4. Schoenfeld, B.J. and Aragon, A.A., 2018. How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution.Journal of the International Society of Sports Nutrition, 15(1), p.10.
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