Youtube is full of bodybuilders who are Vegan and think you should be too. Some of my favorites are Derek Simnet, Jon Venus and Brian Turner, but despite the obvious success of these guys, is a plant based diet truly the best for building muscle?

Our take: of course, it is entirely possible to build muscle on a Vegan diet, but as I explain below, the bodybuilding buzz is largely hype.

Nevertheless, documentaries like The Game Changers really push the idea that you can go Vegan and get ripped, even going so far as to suggest that it’s the best way to build muscle by featuring a roster of Vegan athlete converts (many of whom would be strong no matter what they ate). And while I don’t dispute that there are some really shredded Vegans, this latest “Vegans are muscle men and women” campaign is misleading for the majority of people consuming the content.

In fact, one of the primary reasons a plant based diet is healthy (it keeps IGF-1 levels in check), is the same reason it’s harder to gain huge amounts of muscle as a Vegan.

To understand why Vegans will usually have a harder time gaining muscle, I will rely heavily on the research of Dr. Valter Longo, head of longevity at USC, and creator of the Fasting Mimicking Diet, a popular new approach to fasting that many in health and wellness circles are raving about.

For those playing along at home, Dr. Longo’s paper titled Protein and Amino Acid Restriction, Aging and Disease; from yeast to humans is worth a read.

Dr. Longo is mostly Vegan. He advocates for a plant based diet plus fish, and the addition of goat and sheep dairy and additional animal protein after age 65 when our IGF-1 levels are the lowest.

Why is Dr. Longo mostly Vegan and what is IGF-1?

Insulin like growth factor, or IGF-1, is a hormone that is responsible for cell growth, both good and bad. We need IGF-1 to grow from children into adults and to build muscle, but high levels of IGF-1 also trigger a pathway, called mTOR, that is thought to be responsible for cancer growth and aging. 1

In order to grow muscle, we have to target pathways associated with the regulation of metabolism and growth. When these pathways are turned off, humans develop fewer diseases, but they also stay skinnier.  For example, researchers discovered a small town in Ecuador where the population lacks growth hormone receptors. These people remain very small in stature throughout their entire lives, but are also largely free of the diseases that plague our western world. 2

Amino acids and IGF-1

Dr. Longo’s research shows that certain amino acids are more effective at activating the growth pathways in the body by increasing IGF-1, which in turn, builds muscle.

However, the same pathways that grow muscle can also increase our risk for a host of different diseases. The muscle building amino acids (which are often also pro-inflammatory) are found in their most potent form in animal protein, or sometimes exclusively in animal protein. Because of different amino acid composition, plant proteins do not have the same “anabolic” effect as do animal proteins.

To quote this paper which appeared in the Journal of Nutrition:

The possible lower anabolic properties of plant-based protein sources may be attributed to the lower digestibility of plant-based sources… The latter may be related to the relative lack of specific essential amino acids in plant- as opposed to animal-based proteins. Furthermore, most plant proteins have a relatively low leucine content, which may further reduce their anabolic properties when compared with animal proteins.

Plant proteins are often low in methionine, tryptophan, lycine and isoleucine, which according to Longo, are among the biggest culprits in increasing IGF-1. This makes plant proteins healthy, but not the ideal source for gaining bodybuilder style muscle mass. It is for this reason that Dr. Longo recommends eating plant sources of protein and largely avoiding animal protein. He makes these recommendations to stay healthy, but not to get “big.”

Plant proteins are tougher to digest

Ever tried eating huge portions of beans or tofu? It’s not easy, and yet this is exactly what the most visible Vegan bodybuilders are forced to do – eat huge quantities of soy, tempeh and other processed meats to make up for the shortfall of BCAAs in their Vegan diets.

Plant based proteins are typically much less digestible than animal proteins and because of fiber content, tougher to eat in the quantities necessary to bulk up and gain muscle. 3The Protein Digestibility Corrected Amino Acid Score (PDCAAS) and Digestible Indispensable Amino Acid Score (DIAAS) are two scales commonly used to rate protein digestibility. Interestingly, soy scores remarkably close to whey in relation to digestibility, but other plant sources such as legumes and rices score markedly lower compared to eggs. Based on these figures, this study recommends that vegan athletes should aim for 1.4-2.0 kg/day of protein intake. This high intake is already in the realm of the 1 g/lb ratio commonly used in the body building community, suggesting that vegan bodybuilders may need to push this further. But no exact research has been performed in such a population. Bottom line here is that if your goal is bodybuilding, it’s much harder to get the nutrients you need from plant proteins.

Are skinny vegans healthier?

I admire the passion of the Vegan community, but there can be no doubt that they are just as aggressive with marketing as many of the industries they criticize.

By claiming that going plant based solves every problem, Vegan world overplays its hand and undermines credibility in the process.

The fact that it’s harder to gain muscle on a Vegan diet is also the triumph of a largely Vegan diet, it is thought to reduce expression of mTOR and therefore reduce the risk of cancer. Dr. Longo’s work corroborates the studies performed by T. Colin Campbell that show a diet comprised of 5% animal protein keeps cancer at bay, but a diet of 20% animal protein turns it on.

But here’s the rub: the amino acid profile of an exclusively plant based diet will make it that much harder to grow muscle. IGF-1 is what grows muscle and it’s the goal of a Vegan diet to keep IGF-1 low. 4


Last modified: 29th November 2020