Plant-based Diets and Exercise Performance
Do omnivorous athletes have an advantage in the gym, or is meat-free best for fitness gains?
“Eat food. Not too much. Mostly plants.”
This quippy dietary advice comes from author Michael Pollan in his book “In Defense of Food.”
Most people would agree with the first two imperatives but not the last.
Indeed, one of the most controversial topics in health and nutrition is whether one should include or exclude — or at the very least limit — animal foods from their diet. Plant-based foods like vegetables, fruits, whole grains, nuts, and legumes all appear to be an important part of most diets (unless you’re in the “vegetables are trying to kill you” camp). However, red meat, poultry, and fish also have crucial nutrients that support health and performance.
A majority of people are omnivores — consuming a variety of plant- and animal-based foods. But of course, some choose to exclude animal products from their diet, and others exclude anything with a tinge of green.
Generally, plant-based diets are recommended for their positive impact on cardiovascular health and their supposed environmental sustainability — though this latter aspect is the subject of much debate. Plant-based diets tend to be lower in saturated fat and higher in plant compounds like antioxidants and polyphenols, which support cardiovascular health.
When it comes to exercise performance, athletes express concerns about the potential drawbacks of cutting out meat from their diet, the main one being an inadequate protein intake which could lead to diminished performance, particularly in strength-based sports.
Despite these concerns, cross-sectional studies have indicated that vegans and vegetarians often exhibit similar or improved muscle strength, endurance, and cardiorespiratory fitness compared to omnivores.
In fact, a recent meta-analysis comparing vegetarian and vegan diets to omnivorous diets indicates that plant-based athletes demonstrate superior aerobic exercise performance to their meat-eating peers. When comparing strength and power, performance was similar — indicating that at the very least, meatless diets aren’t detrimental to performance.
A bit more info on this meta-analysis (a study of studies). A total of 10 articles were included, some of which were observational (studied people habitually consuming plant-based or omnivorous diets) and some of which were randomized controlled trials that assigned participants to different dietary regimens.
Given the different assessments used to measure aerobic exercise performance and strength/power, we can’t conclude much from this study. However, it is interesting to speculate why plant-based diets support better aerobic exercise performance.
I had a brief interaction on Twitter (X) about this.
Surprisingly, few studies have directly compared the performance effects of diets predominantly featuring plant-based or animal-based protein sources. This is because naturally, a long-term experiment of this sort is hard to conduct.
Swapping out meat for performance gains?
A recent study known as the SWAP-MEAT Athlete study (the acronym stands for “study with appetizing plant-food meat eating alternatives trial…quite the mouthful, pun intended) not only compared plant-based diets to meat-containing diets but also studied the effects of plant-based meat alternatives (another touchy subject…let’s not get into it).
Twenty-two recreational athletes (average age 27) were assigned to one of three diets for 4 weeks, with each participant completing all 3 diets. Some participants were primarily aerobic-exercise trained (“runners”) and some were primarily resistance-exercise trained (“lifters”).
Here’s a description of the diets:
Whole Food Plant-Based Diet (WFPB): Emphasized vegetables, legumes, fruits, nuts, seeds, and whole grains with protein sources like quinoa, beans, and tofu. Animal products and processed foods were restricted.
Plant-Based Meat Alternatives (PBMA): Incorporated at least two servings per day of plant-based meat alternatives (e.g., Beyond Meat, Impossible Burger). Dairy and eggs were allowed, but no animal meat was permitted except fish once a week.
Omnivorous Diet (Animal): Included at least two servings of animal meat per day, predominantly red meat or poultry, with fish once a week.
Participants maintained their physical activity levels and logged their dietary intake on three days per week.
What were the results?
Keep reading with a 7-day free trial
Subscribe to Physiologically Speaking to keep reading this post and get 7 days of free access to the full post archives.