In the movie RockySylvester Stallone eats raw eggs for breakfast before facing Apollo Creed. A cult scene combining physical performance… and animal proteins ! Fifty years later, would the boxer rather draw a shaker of vegetable proteins powder? Are these alternatives really effective for gaining muscle?
What does muscle need to grow?
Muscle development relies on the interaction of three main factors: mechanical stimulation, nutritional intake and recovery. “ When a muscle is used repeatedly, mechanical stress causes slight alterations in the muscle fibers. Their repair requires an adequate intake of proteins, particularly essential amino acids, such as leucine, which plays a key role in the activation of muscle synthesis », explains Raphaël Gruman. This process is not limited to a simple repair: the body rebuilds the fibers, making them thicker and more resistant in order to better adapt to future efforts.
Do plant proteins help build muscle mass?
Although the animal proteins are generally considered more effective in stimulating muscle synthesis — due to their better digestibility and their richness in essential amino acids — several studies show that the source of protein has a limited influence on lean mass and strength, as long as total protein intake is sufficient. A meta-analysis published in July 2025 (Effect of plant versus animal proteins on muscle mass, strength, physical performance and sarcopenia) reports a slight benefit of animal protein on muscle mass in young adults, but not in older adults. She also emphasizes that soy proteins are equivalent to animal proteins in maintaining or improving muscle massregardless of age, and that no significant difference appears in the absence of resistance training.
These results echo those of a 2021 meta-analysis published in the journal Nutrientswho observes a slightly more favorable effect of animal proteins on lean mass, especially in young adults.
« Whether plant proteins are sufficient to maintain muscle mass in less active people, among athletes, the situation is more complex, explains Raphaël Gruman. Some high-level athletes are vegetarian or vegan, but this requires a good mastery of nutrition. It may be more difficult to optimize strong muscle growth with plant-based proteins alone. In this context, an appropriate protein intake, possibly supplemented by food supplements such as creatine, can be useful. »
Are they as effective as animal proteins?
Yes, with equal protein intake, muscle gains can be comparable. However, achieving these intakes can be more restrictive with plant sources: you often need more quantity… and you quickly reach saturation! “Consuming plant-based proteins like quinoa or lentils can quickly lead to a feeling of fullness, due to their high fiber content.confirms the dietician-nutritionist. This is why some vegetarian or vegan athletes use more concentrated vegetable protein powders in order to increase their intake without excessively increasing the food volume. Conversely, animal proteins are generally more protein dense and easier to consume in large quantities.”
Bodybuilding: what is the most effective plant protein?
To maintain muscle mass, vegetable proteins are more than enough, provided you consume a sufficient quantity and vary the sources. “ All essential amino acids are not always present in optimal quantities in a single plant source, which is why it is interesting to combine them during the day or during a meal: for example, lentils-rice or red beans-rice. »
On the other hand, when it comes to developing muscle mass, soy is one of the best options. It contains all the essential amino acids in proportions favorable to muscle synthesis, with an effectiveness close to that of animal proteins. Other sources, such as pea or rice protein, can also support muscle gain, when combined to provide a complete profile.
