Aug 09, 2021 in DIS-TANZ-SOLO

Nutrition is a major concern for virtually all athletes, and especially when it comes to strength training programs, adequate protein intake is a key consideration.

There are a number of myths associated with high-protein diets (e.g. that they lead to osteoporosis and kidney damage) but most of them have now been debunked. At the bottom of the page you will find links to a number of systematic reviews and meta-analyses that deal with these topics in detail.

Another question that is always discussed is how much protein the body can actually absorb. However, this is a misleading discussion, because ultimately the question is not how much protein is absorbed (all of it!), but how large a proportion can actually be utilized for building muscle.

The rough guideline would be to consume about 1,6 – 2,4g per kg per day, and 20 – 40g per sitting, but it is important to remember that these numbers depend on many different factors: age, body size, proportion of lean body mass, amount of muscle mass being trained, etc.

Also, the time window for protein intake, which has long been considered to be 30-60 minutes after training, is not necessarily correct. It rather seems that the time frame is significantly larger and therefore you are pretty much on the safe side as long as you spread your meals evenly throughout the day.

Read on through the article to get plenty more important information about the role of protein and to discover a range of useful resources on the topic.

Muscle Protein Synthesis

When you eat protein, the protein is broken down into amino acids. These amino acids are absorbed in the intestine and then released into the bloodstream, from where they can be transported to the peripheral tissues and built up into tissue protein. The process of building new proteins is called protein synthesis, which basically takes place in all organs. Accordingly, muscle protein synthesis specifically refers to the process of building muscle protein.

There is an opposing process called muscle protein breakdown. Both of these processes occur constantly and simultaneously in the body. The speed at which the two processes take place determines whether you gain or lose muscle mass. If muscle protein synthesis exceeds muscle protein breakdown, your muscles will grow. If, on the other hand, muscle protein breakdown exceeds muscle protein synthesis, you will lose muscle mass.

Both muscle protein synthesis and muscle protein breakdown are important metabolic components of muscle remodelling, adaptation to training and muscle mass gain. But since muscle protein breakdown in healthy individuals is only marginally influenced by exercise, we want to focus on muscle protein synthesis.

A recent study by Felipe Damas et al. showed that while untrained subjects have a large increase in muscle protein synthesis after their first training sessions, they also have a lot of muscle damage. So in the early stages, muscle protein synthesis is mainly used to repair damaged muscle protein, not for growth. But after only 3 weeks of training, the muscle damage is significantly reduced and the increase in muscle protein synthesis is actually used for muscle hypertrophy.

Now if you have listened to Brad Schoenfeld and his guidelines for muscle hypertrophy in my recent post THE HYPERTROPHY SPECIALIST, then you already know what factors are involved in optimizing muscle growth. To recap very briefly: Multiple sets appear to stimulate muscle protein synthesis more effectively than a single set. Different repetition ranges are equally effective in stimulating muscle protein synthesis as long as the set is performed close to failure. Too short rest periods between sets decrease muscle protein synthesis rates. It is suboptimal to train a muscle group only once a week. In more trained athletes, the increase in muscle protein synthesis is lower, but so is the muscle damage after strength training.

Muscle metabolism expert Dr. Jorn Trommelen recommends the following nutritional guidelines for optimal muscle protein synthesis on his website nutritiontactics.com: Eat 4-5 meals throughout the day: e.g. breakfast, lunch, post-workout shake, dinner and before bed. Consume 20-40 g protein at each meal. Amounts above 20 g provide a small additional benefit. Choose animal protein (whey protein is the best). Or compensate by eating larger amounts of plant protein (more on this in the following section). If your main goal is to build muscle, you should consume at least maintenance calories.

Michael Loehr - The Power of Protein - Animal Protein Photo
Michael Loehr - The Power of Protein - Plant Protein Photo

Animal vs. Plant Protein

The discussion about nutrition is an extraordinarily emotional one. That is why I have so far avoided making recommendations in one direction or another. However, there are a few differences worth knowing when it comes to deciding between animal and plant proteins.

When we talk about high-quality proteins, we mean that they have a well balanced spectrum of all nine essential amino acids (histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine).

As a general rule, animal-based proteins such as meat, dairy products and eggs contain all the essential amino acids. In contrast, most plant-based proteins from foods such as beans, grains, nuts and soy are rich in some amino acids, while others may be lacking.

While a number of plant-based proteins, such as quinoa, buckwheat and spirulina, do actually contain all the essential amino acids, the levels of some of these amino acids are too low to form a balanced and therefore 'useful' protein. This means that when building muscle, if you rely solely on such an unbalanced protein as your protein source, there is naturally a limit to how much muscle mass you can build.

But that doesn't mean you're necessarily screwed as a vegan athlete, you just have to put in a little more effort. One option would be to choose one of the above-mentioned plant protein sources (one that is unbalanced but has all essential amino acids) and simply consume more of that one protein to eventually have enough of the least available amino acid in the body. But that would surely not be very practical.

A better way is to combine different plant proteins with complementary amino acid profiles and thereby cover the full spectrum needed. This requires an extra level of research and mindfulness when putting together one's meals, but it is undoubtedly possible.

Protein Sources

Among the most protein-rich foods are chicken, beef, tuna, soy, lentils, beans, Greek yoghurt, cottage cheese and eggs. I have compiled a PDF with the PROTEIN CONTENT OF SELECTED FOODS to give you an introductory overview. Naturally, one could extend such lists ad infinitum, but I think it contains enough information to give a solid starting point for managing your protein supply.

Please keep in mind that the nutritional information of certain products may vary depending on the manufacturer. Especially when it comes to targeted nutrition and achieving specific training goals, it is always advisable to double-check the information on the food packaging.

Michael Loehr - The Power of Protein - Protein Content PDF

Orgainic Whey Protein

For quite a while I have been looking for a protein shake that is not completely over-sugared and free of artificial flavours and chemical additives. Although I've had a handful of recommendations over time, most of the shakes I've tried have been rather unpleasant to drink. That's why I was quite happy when I discovered the German brand ORGAINIC, which specialises in organic sports nutrition without additives.

Their whey protein is sourced from grass-fed cows in Bavaria and Austria, contains all essential amino acids and BCAAs, and the 'natural' flavour really only has one single ingredient: organic whey protein concentrate.

Anyone expecting a really intense-tasting drink, like a sweet milkshake, will of course be disappointed. But the fact that this 'natural' whey contains no flavourings does not mean that the protein shake has no taste. It tastes like natural whey powder. In addition, ORGAINIC does not use solubilizers, which means that you may have to put a little more effort into shaking to dissolve the powder completely. These are a few things to keep in mind when buying so as not to be unpleasantly surprised.

In any case, I was completely convinced by this product and can warmly recommend it. For those looking for a little more flavour, there are also vanilla, cocoa, strawberry and blueberry flavours to choose from. For all vegans, there is also a vegan protein that consists of 60% rice protein and 40% pea protein and thus equally covers the entire spectrum of essential amino acids. Give it a try and let me know what you think.

Michael Loehr - The Power of Protein - Orgainic Whey Protein
Learn more about ORGAINIC's food supplements without artificial additives and shop their whey protein or vegan protein on their website orgainic.com

Listen and learn from Jeff & Jorn

To give you even more insight into the power of protein, here is a conversation between professional natural bodybuilder and powerlifter Jeff Nippard and muscle protein synthesis expert Dr. Jorn Trommelen. The first part deals more with the training aspects of the topic, while the second part focuses more on the issue of nutrition. All in all, it's two and a half hours of information-packed conversation.

When you open the videos, you will be able to see the timestamps and the individual topics covered, so you can navigate directly to the questions that particularly catch your interest.

If you still haven't had enough and would like to learn even more about the role of proteins in muscle growth, or need a more structured overview to recap what you've heard in the videos, I recommend you take a look at Jorn Trommelen's Ultimate Guide to Muscle Protein Synthesis. His article really gives a comprehensive overview of all the important aspects on this topic. Even more than the video discussion, it is dense with a lot of very detailed information, but in its easy-to-understand language it is still aimed at any curious athlete who is interested in the relevant scientific background to better achieve their training goals.

Relevant scientific papers and articles


A systematic review, meta-analysis and meta- regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults

by Robert W. Morton, Kevin T. Murphy, Sean R. McKellar, Brad J. Schoenfeld, Menno Henselmans, Eric Helms, Alan A. Aragon, Michaela C. Devries, Laura Banfield, James W. Krieger & Stuart M. Phillips
(British Journal of Sports Medicine 52/6, March 2018)

Objective: We performed a systematic review, meta-analysis and meta-regression to determine if dietary protein supplementation augments resistance exercise training (RET)-induced gains in muscle mass and strength. / Data sources: A systematic search of Medline, Embase, CINAHL and SportDiscus. / Eligibility criteria: Only randomised controlled trials with RET ≥6 weeks in duration and dietary protein supplementation. / Design: Random-effects meta-analyses and meta-regressions with four a priori determined covariates. Two-phase break point analysis was used to determine the relationship between total protein intake and changes in fat-free mass (FFM). / Results: Data from 49 studies with 1863 participants showed that dietary protein supplementation significantly (all p<0.05) increased changes (means (95% CI)) in: strength—one-repetition-maximum (2.49 kg (0.64, 4.33)), FFM (0.30 kg (0.09, 0.52)) and muscle size—muscle fibre cross-sectional area (CSA; 310 µm2 (51, 570)) and mid-femur CSA (7.2 mm2 (0.20, 14.30)) during periods of prolonged RET. The impact of protein supplementation on gains in FFM was reduced with increasing age (−0.01 kg (−0.02,–0.00), p=0.002) and was more effective in resistance-trained individuals (0.75 kg (0.09, 1.40), p=0.03). Protein supplementation beyond total protein intakes of 1.62 g/kg/day resulted in no further RET-induced gains in FFM. / Summary/conclusion: Dietary protein supplementation significantly enhanced changes in muscle strength and size during prolonged RET in healthy adults. Increasing age reduces and training experience increases the efficacy of protein supplementation during RET. With protein supplementation, protein intakes at amounts greater than ~1.6 g/kg/day do not further contribute RET-induced gains in FFM.


A Systematic Review of Dietary Protein During Caloric Restriction in Resistance Trained Lean Athletes: A Case for Higher Intakes

by Eric R. Helms, Caryn Zinn, David S. Rowlands & Scott R. Brown
(International Journal of Sport Nutrition and Exercise Metabolism 24/2, April 2014)

Caloric restriction occurs when athletes attempt to reduce body fat or make weight. There is evidence that protein needs increase when athletes restrict calories or have low body fat. The aims of this review were to evaluate the effects of dietary protein on body composition in energy-restricted resistance-trained athletes and to provide protein recommendations for these athletes. Database searches were performed from earliest record to July 2013 using the terms protein, and intake, or diet, and weight, or train, or restrict, or energy, or strength, and athlete. Studies (N = 6) needed to use adult (≥ 18 yrs), energy-restricted, resistance-trained (> 6 months) humans of lower body fat (males ≤ 23% and females ≤ 35%) performing resistance training. Protein intake, fat free mass (FFM) and body fat had to be reported. Body fat percentage decreased (0.5–6.6%) in all study groups (N = 13) and FFM decreased (0.3–2.7kg) in nine of 13. Six groups gained, did not lose, or lost nonsignificant amounts of FFM. Five out of these six groups were among the highest in body fat, lowest in caloric restriction, or underwent novel resistance training stimuli. However, the one group that was not high in body fat that underwent substantial caloric restriction, without novel training stimuli, consumed the highest protein intake out of all the groups in this review (2.5–2.6g/kg). Protein needs for energy-restricted resistance-trained athletes are likely 2.3–3.1g/kg of FFM scaled upwards with severity of caloric restriction and leanness.


Changes in Kidney Function Do Not Differ between Healthy Adults Consuming Higher- Compared with Lower- or Normal-Protein Diets: A Systematic Review and Meta-Analysis

Michaela C. Devries, Arjun Sithamparapillai, K. Scott Brimble, Laura Banfield, Robert W Morton & Stuart M. Phillips
(The Journal of Nutrition 148/11, November 2018)

Higher-protein (HP) diets are advocated for several reasons, including mitigation of sarcopenia, but their effects on kidney function are unclear. This meta-analysis was conducted to determine the effect of HP intakes on kidney function in healthy adults. We conducted a systematic review and meta-analysis of trials comparing HP (≥1.5 g/kg body weight or ≥20% energy intake or ≥100 g protein/d) with normal- or lower-protein (NLP; ≥5% less energy intake from protein/d compared with HP group) intakes on kidney function. Medline and EMBASE databases were searched. Randomized controlled trials comparing the effects of HP with NLP (>4 d duration) intakes on glomerular filtration rate (GFR) in adults without kidney disease were included. A total of 2144 abstracts were reviewed, with 40 articles selected for full-text review; 28 of these were analyzed and included data from 1358 participants. Data were analyzed using random-effects meta-analysis (RevMan 5; The Cochrane Collaboration), meta-regression (STATA; StataCorp), and dose-response analysis (Prism; GraphPad). Analyses were conducted using postintervention (post) GFR and the change in GFR from preintervention to post. The post-only comparison showed a trivial effect for GFR to be higher after HP intakes [standardized mean difference (SMD): 0.19; 95% CI: 0.07, 0.31; P = 0.002]. The change in GFR did not differ between interventions (SMD: 0.11; 95% CI: −0.05, 0.27; P = 0.16). There was a linear relation between protein intake and GFR in the post-only comparison (r = 0.332, P = 0.03), but not between protein intake and the change in GFR (r = 0.184, P = 0.33). The main limitation of the current analysis is the unclear risk of selection bias of the included trials. Postintervention GFR comparisons indicate that HP diets result in higher GFRs; however, when changes in GFR were compared, dietary protein had no effect. Our analysis indicates that HP intakes do not adversely influence kidney function on GFR in healthy adults.


Dietary protein and bone health: a systematic review and meta-analysis from the National Osteoporosis Foundation

Marissa M. Shams-White, Mei Chung, Mengxi Du, Zhuxuan Fu, Karl L. Insogna, Micaela C. Karlsen, Meryl S. LeBoff, Sue A. Shapses, Joachim Sackey, Taylor C. Wallace & Connie M. Weaver
(The American Journal of Clinical Nutrition 105/6, June 2017)

Considerable attention has recently focused on dietary protein’s role in the mature skeleton, prompted partly by an interest in non-pharmacologic approaches to maintain skeletal health in adult life. The aim was to conduct a systematic review and meta-analysis evaluating the effects of dietary protein intake alone and with calcium with or without vitamin D (Ca6D) on bone health measures in adults. Searches across 5 databases were conducted through October 2016 including randomized controlled trials (RCTs) and prospective cohort studies examining 1) the effects of “high versus low” protein intake or 2) dietary protein’s synergistic effect with Ca6D intake on bone health outcomes. Two investigators independently conducted abstract and full-text screenings, data extractions, and risk of bias (ROB) assessments. Strength of evidence was rated by group consensus. Random-effects meta-analyses for outcomes with $4 RCTs were performed. Sixteen RCTs and 20 prospective cohort studies were included in the systematic review. Overall ROB was medium. Moderate evidence suggested that higher protein intake may have a protective effect on lumbar spine (LS) bone mineral density (BMD) compared with lower protein intake (net percentage change: 0.52%; 95% CI: 0.06%, 0.97%, I2: 0%; n = 5) but no effect on total hip (TH), femoral neck (FN), or total body BMD or bone biomarkers. Limited evidence did not support an effect of protein with Ca6D on LS BMD, TH BMD, or forearm fractures; there was insufficient evidence for FN BMD and overall fractures. Current evidence shows no adverse effects of higher protein intakes. Although there were positive trends on BMD at most bone sites, only the LS showed moderate evidence to support benefits of higher protein intake. Studies were heterogeneous, and confounding could not be excluded. High-quality, long-term studies are needed to clarify dietary protein’s role in bone health.

Surgery Journal Cover

Digestion and absorption

Anthony D. Jackson & John McLaughlin
(Surgery 27/6, June 2009)

The gastrointestinal tract exists to support nutrition, digesting and assimilating nutrients including water and salts. Disorders of the gut readily impair nutritional status, although there is considerable functional reserve. Many macronutrients are structural components of animals and plants, and therefore ingested in complex molecular forms that cannot be readily absorbed. They must be digested to simpler components in the gastrointestinal tract before absorption and assimilation can occur. For the major complex macronutrients, (fat, carbohydrate, protein), the gut secretes specific enzymes that catalyse the hydrolysis of these nutrients to their basic oligomeric subunits, which are then taken up by specific transport proteins expressed in the epithelial membrane for optimal transport from the lumen into enterocytes. The digestive process is progressive, beginning in the oral cavity and continuing during passage to the small intestine, the key site of most nutrient absorption. The colonic bacterial flora salvages nutrients from otherwise indigestible fibre. Micronutrients (vitamins, minerals), electrolytes and water must be absorbed; specific transport mechanisms exist for each. The magnitude of specialized processes that act in conjunction to enable effective digestion and absorption (along with the regulatory inputs that converge to coordinate these events) demonstrate how finely adapted the gastrointestinal tract is to its function.

Computational and Structural Biotechnology Journal Cover

High Versus low Dietary Protein Intake and Bone Health in Older Adults: a Systematic Review and Meta-Analysis

Inge Groenendijk, Laura den Boeft, Luc J.C. van Loon & Lisette C.P.G.M. de Groot
(Computational and Structural Biotechnology Journal 19, 2019)

Protein may play a beneficial role in the prevention of bone loss and in slowing down osteoporosis. The effect of dietary protein may be different in older adults compared to younger adults, since this population has a greater need for protein. The aim of this systematic review and meta-analysis was to investigate the impact of a dietary protein intake above the Recommended Dietary Allowance (RDA) of 0.8 g/kg body weight/day from any source on Bone Mineral Density (BMD)/Bone Mineral Content (BMC), bone turnover markers, and fracture risk in older adults compared to a lower dietary protein intake. A systematic search was conducted through October 2018 in 3 databases: CENTRAL, MEDLINE, and EMBASE. We included all prospective cohort studies and Randomized Controlled Trials (RCTs) among adults aged ≥65 years that examined the relation between protein intake on bone health outcomes. Two investigators independently conducted abstract and full-text screenings, data extractions, and risk of bias assessments. Authors were contacted for missing data. After screening of 523 records, twelve cohort studies and one RCT were included. Qualitative evaluation showed a positive trend between higher protein intakes and higher femoral neck and total hip BMD. Meta-analysis of four cohort studies showed that higher protein intakes resulted in a significant decrease in hip fractures (pooled hazard ratio: 0.89; 95% confidence interval: 0.84, 0.94). This systematic review supports that a protein intake above the current RDA may reduce hip fracture risk and may play a beneficial role in BMD maintenance and loss in older adults.


Protein Recommendations for Weight Loss in Elite Athletes: A Focus on Body Composition and Performance

Amy J. Hector & Stuart M. Phillips
(International Journal of Sport Nutrition and Exercise Metabolism 28/2, January 2018)

There exists a large body of scientific evidence to support protein intakes in excess of the recommended dietary allowance (RDA) (0.8 g protein/kg/day) to promote the retention of skeletal muscle and loss of adipose tissue during dietary energy restriction. Diet-induced weight loss with as low as possible ratio of skeletal muscle to fat mass loss is a situation we refer to as high-quality weight loss. We propose that high-quality weight loss is often of importance to elite athletes in order to maintain their muscle (engine) and shed unwanted fat mass, potentially improving athletic performance. Current recommendations for protein intakes during weight loss in athletes are set at 1.6–2.4 g protein/kg/day. However, the severity of the caloric de!cit and type and intensity of training performed by the athlete will influence at what end of this range athletes choose to be. Other considerations regarding protein intake that may help elite athletes achieve weight loss goals include the quality of protein consumed, and the timing and distribution of protein intake throughout the day. This review highlights the scienti!c evidence used to support protein recommendations for high-quality weight loss and preservation of performance in athletes. Additionally, the current knowledge surrounding the use of protein supplements, branched chain amino acids (BCAA), β-hydroxy β-methylbutyrate (HMB), and other dietary supplements with weight loss claims will be discussed.

The Journal of Physiology Cover

Resistance training-induced changes in integrated myofibrillar protein synthesis are related to hypertrophy only after attenuation of muscle damage

Felipe Damas, Stuart M. Phillips, Cleiton A. Libardi, Felipe C. Vechin, Manoel E. Lixandrão, Paulo R. Jannig, Luiz A. R. Costa, Aline V. Bacurau, Tim Snijders, Gianni Parise, Valmor Tricoli, Hamilton Roschel & Carlos Ugrinowitsch
(The Journal of Physiology 594/18, September 2016)

Skeletal muscle hypertrophy is one of the main outcomes of resistance training (RT), but how hypertrophy is modulated and the mechanisms regulating it are still unknown. To investigate how muscle hypertrophy is modulated through RT, we measured day-to-day integrated myofibrillar protein synthesis (MyoPS) using deuterium oxide and assessed muscle damage at the beginning (T1), at 3 weeks (T2) and at 10 weeks of RT (T3). Ten young men (27 (1) years, mean (SEM)) had muscle biopsies (vastus lateralis) taken to measure integrated MyoPS and muscle damage (Z-band streaming and indirect parameters) before, and 24 h and 48 h post resistance exercise (post-RE) at T1, T2 and T3. Fibre cross-sectional area (fCSA) was evaluated using biopsies at T1, T2 and T3. Increases in fCSA were observed only at T3 (P = 0.017). Changes in MyoPS post-RE at T1, T2 and T3 were greater at T1 (P < 0.03) than at T2 and T3 (similar values between T2 and T3). Muscle damage was the highest during post-RE recovery at T1, attenuated at T2 and further attenuated at T3. The change in MyoPS post-RE at both T2 and T3, but not at T1, was strongly correlated (r ≈ 0.9, P < 0.04) with muscle hypertrophy. Initial MyoPS response post-RE in an RT programme is not directed to support muscle hypertrophy, coinciding with the greatest muscle damage. However, integrated MyoPS is quickly ‘refined’ by 3 weeks of RT, and is related to muscle hypertrophy. We conclude that muscle hypertrophy is the result of accumulated intermittent changes in MyoPS post-RE in RT, which coincides with progressive attenuation of muscle damage.

Header photo by Evan Lorne on Shutterstock
Animal protein image by Yulia Furman on Shutterstock
Plant protein image by Oleksandra Naumenko on Shutterstock
PDF button image by stockcreations on Shutterstock, Edited by Michael Loehr


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