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Muscle gains : are animal proteins superior to plant-based proteins?

by P. Debraux | 3 March 2023

muscle, gains, protein, animal, plant-based, nutrition, diet, exercise, alternative

Muscle tissue responds to mechanical stress (such as resistance training) by changing its architecture through the accumulation of myofibrillar proteins. This results in an increase in muscle volume called hypertrophy. Strength training is the best natural stimulus to increase muscle protein synthesis. And to support this growth, the macronutrient composition of our diet is particularly important. Thus, the ideal dietary protein intake to maximize muscle gains seems to be around 1.6 g/kg/day (kg body mass, not lean mass), on average.

While the optimal amount of protein for optimal muscle gain is now fairly well defined, the question of where it comes from remains unresolved. Indeed, most of the studies that have looked at this question have mainly used omnivorous diets in which proteins were mainly derived from animal sources (meat, fish, milk proteins). It is therefore difficult to know if these recommendations could be applied to the vegan diet.

Unlike the vegetarian diet, which excludes only meat, fish and seafood, the vegan diet bans the consumption of all animal products: meat, fish, seafood, but also eggs, dairy products, honey, gelatin, etc. The term "integral/environmental vegan" goes even further by extending this philosophy to all products derived from animal exploitation (clothing, cosmetics, certain medicines, etc.).

Plant-based proteins are generally considered inferior to proteins of animal origin. They would stimulate a lower rate of myofibrillar protein synthesis and would not allow to sustain as good a hypertrophy on the long term... However, more and more studies show similar results, whatever the diet adopted, and whatever the audience studied. So what's really going on?

The Study

To answer this question, British and American researchers compared the effects of a diet with proteins of exclusively animal origin with a diet with proteins of exclusively vegetable origin in young adults, resistance training practitioners, on the rate of muscle protein synthesis and on gains in muscle mass. To do this, the research team divided the study into 2 phases.

In the first phase, 16 people (8 women and 8 men) were divided into 2 groups, each group following a diet based on the source of protein (animal vs. vegetable) (1.8 g/kg/d). For 3 successive days, they performed 5 sets of 30 repetitions of unilateral and concentric knee extension on an isokinetic machine. Each day, the rate of muscle protein synthesis at rest and after exercise was measured.

In the second phase, 22 individuals (11 women and 11 men) participated in a 10-week training program with 5 sessions per week. The major muscle groups were trained twice a week. During these 10 weeks, the participants were divided into two groups based on their diet and the source of their protein (animal vs. vegetable [mainly from mushrooms]). In both cases, they ingested approximately 2 g/kg/d of protein per day. In addition, all participants were supplemented with creatine monohydrate.

Vastus lateralis muscle fiber cross-sectional area, whole body lean mass, thigh muscle volume, and maximal strength in the deadlift, squat, and incline bench press were assessed before and after the 10-week intervention.

Results & Analyzes

The main results of this study show that a diet rich in plant-based proteins allows a rate of muscle protein synthesis similar to that of a diet rich in animal proteins. And these results are confirmed after 10 weeks of bodybuilding training, an omnivorous or vegan diet, rich in protein (>1.6 g/kg/d), allows to obtain the same gains in muscle mass and strength, in young adults.

In 10 weeks, participants gained an average of 2.8 kg of lean mass, 8.3% of volume in the thigh and 32% of sectional area in the muscle fibres. These gains were achieved in a relatively linear fashion throughout the 10 weeks at a rate of +0.55% / week for lean mass, +0.83% / week for thigh volume and +3.2% for muscle fiber cross-sectional area. The gains in lean mass were 3.6 kg for men and 2.1 kg for women. This is comparable to results obtained in other studies over the same training periods.

Generally, plant-based proteins have a poor reputation and are considered inferior to animal-based proteins in their potential to support muscle hypertrophy. These results often come from studies that only look at the rate of muscle protein synthesis via low quality plant protein supplementation. The results of this study demonstrate the opposite: a diet and supplementation based mainly but not exclusively on mycoproteins (mushroom proteins) is a real alternative to an omnivorous diet.

Practical Applications

These results support emerging evidence suggesting that the vegan diet may be able to equivalently support skeletal muscle adaptive responses to strength training, assuming sufficient daily protein intake (≥ 1.6 g/kg/d) and overall caloric surplus. However, the researchers note that it appears more difficult for participants, from a practical standpoint, to achieve the set daily amount of protein in the vegan diet. In addition, for the vegan diet, specific supplementation, especially in vitamin B12, appears necessary to avoid certain deficiencies.

After 10 weeks of weight training, with 5 weekly sessions, comparable increases in muscle fiber size, muscle volume, whole body lean mass and muscle strength were observed. Thus, a carefully designed vegan diet (implying different plant protein sources to combine aminograms) would allow for equally significant gains. So all proteins should be considered. Even if a plant-based protein, in isolation, does not have the same aminogram as an animal protein, the problem must be approached holistically and all sources must be taken into account.


  1. Monteyne AJ, Coelho MO, Murton AJ, Abdelrahman DR, Blackwell JR, Koscien CP, Knapp KM, Fulford J, Finnigan TJ, Dirks ML, Stephens FB & Wall BT. Vegan and omnivorous high protein diets support comparable daily myofibrillar protein synthesis rates and skeletal muscle hypertrophy in young adults. J Nutr, Article in Press, 2023.

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