Physiology Friday #139: Does Swapping Meat for a Plant-based diet Improve Athletic Performance?
Here's what happens to strength and endurance when omnivores go meat-free.
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Plant vs. Animal Protein for Performance
Ethical considerations aside, there will always be debate about whether plant-based diets or omnivorous diets are superior for human health. Science hasn’t done a great job of helping us elucidate the “optimal human diet” either. One week, red meat is killing us and eggs are clogging our arteries; the next week, eggs are lowering our risk for diabetes and red meat is absolved of all of its sins against heart health. Because most of these associations are just that — associations — they don’t really provide insight into whether eating these foods is causing disease.
A similar plant-based vs. animal-based battle is ongoing in the sports performance world, and the topic of discussion usually centers around protein. Can vegan and vegetarian athletes get enough protein — and enough high-quality protein at that — from a plant-based diet? Some would argue no, but vegan bodybuilders or plant-based endurance athletes (who are highly successful) would tend to disagree. There are examples all over social media of athletes succeeding on meat-heavy or meat-free diets.
The best way to isolate the effects of a dietary factor on performance is to conduct a randomized controlled trial. If we’re ever going to find an answer about the benefits or detriments of a plant-based diet for performance, well-controlled studies are a necessary starting point.
What happens when omnivores go meat-free?
A new study — aptly titled the SWAP-MEAT Athlete study— pitted three different diets head to head to determine, once and for all (joking, of course), whether plant or animal protein is superior for athletic performance.
22 recreational athletes were enrolled in the study. Eleven of the participants were runners, and the other half participated in resistance training.
Everyone was placed on 1 of 3 different diets, each for 4 weeks at a time.
One diet was a whole food plant-based diet (WFPB) which contained at least two meals per day emphasizing the intake of vegetables, legumes, fruits, nuts, seeds, and whole grains, with protein sources including quinoa, beans, and tofu. The intake of processed foods, eggs, and dairy was minimized, and participants weren’t allowed to eat meat, plant-based meat alternatives, or fish.
Another diet was a plant-based meat alternatives (PBMA) diet consisting of at least two servings per day of plant-based meat alternative protein sources (i.e., Beyond Meat, Impossible Burger). Dairy and eggs were permitted, but participants weren’t allowed to eat meat, and fish was allowed just once per week.
The last diet was an omnivorous diet (Animal) consisting of at least two servings of animal meat per day, predominantly in the form of red meat or poultry. Participants were allowed to eat fish once per week.
At the beginning of the study and after each diet phase, participants’ performance, body weight, and body fat % were measured.
The runners completed a 12-minute run and performed a VO2 max test. The resistance training group completed a maximal set of push-ups and pull-ups, and their strength was assessed on three different exercises: chest press, leg press, and lateral pulldown.
None of the performance outcomes were different between the diet groups. Runners covered the same distance during the 12-minute run after the WFPB, PBMA, and Animal diets. They also had a similar VO2 max after each diet. However, the runners did reduce their body weight and body fat % after the plant-based diets when compared to the Animal diet.
The resistance training group had the same strength, maximal pull-ups, and maximal pull-ups after each diet. Their body weight and body fat % was lower after the WFPB diet compared to the Animal diet.
Regarding dietary intake, all of the 3 diets provided adequate protein to meet the recommended levels for the participants’ activity levels: 72 grams per day on the WFPB diet, 85 grams per day on the PBMA diet, and 107 grams per day on the Animal diet (significantly higher than the plant-based diets). They also consumed adequate dietary carbohydrates (for their activity level) on each diet, though carbohydrate intake was slightly lower in the Animal diet compared to the plant-based diets.
One interesting thing to note is that during the study, participants reported that it was harder to adhere to the plant based meat alternative diet, due to a greater difficulty finding the “fake meats” in restaurants and purchasing them in stores. They seemed to rate the plant-based and the Animal diet similar in terms of feasibility and adherence.
What can we conclude from these findings? The 4-week duration (quite short for a dietary intervention) precludes me from saying that meat-free and meat-containing diets are equally good when it comes to supporting athletic performance. If we extended this study to 6 months, a year, or longer, then the small differences in protein or other nutrients between the two diets might actually manifest in performance outcomes.
But, I do think that, overall, if someone chooses to eat meat or consume a mostly plant-based diet, both can support health and performance as long as energy intake is adequate, macronutrients carefully tracked, and no real deficiencies are present.
Would these same results hold up in a population of elite athletes with a much heavier training volume? I’m not sure. There are plenty of examples of plant-based strength and endurance athletes who have been quite successful sans meat. These anecdotes can be powerful, but most people involved in the diet wars want hard data, not n=1 studies.
I’ve been plant based before, and I’ve run some of my personal best performances on a vegan(ish) diet. Now, I eat plenty of meat, and my health and performance are just as good as ever. Each of us has to experiment with our own nutrition to find what works best in the long run. It’s part of the fun of life and athletics. I’m not sure I’ll ever cut out meat from my diet again, but I completely support those who do, and think this dietary pattern can be a path to a healthy life and successful athletic achievement.
Thanks for reading.
See you next Friday.