“Animal products in human diets provide an important source of energy”
— National Cattlemen’s Beef Association (1)
While the notion that meat, dairy and eggs are necessary for protein is by far the most pervasive and dangerous myth associated with animal-based foods, another common myth is that without these foods you won’t have enough “energy”.
As Dr. James Loomis — former team physician for the World Series-winning St. Louis Cardinals and Super Bowl-winning St. Louis Rams — explains in The Game Changers:
“You would go to a pre-game dinner with the football team and would see this spread. There would be steak and chicken, very much protein oriented, because their perception was that the protein is what sustains their energy, but in fact, that's not the case.”
As further explained in the film, the “scientific” beginning of this misconception can be traced back to Baron Justus von Liebig, a famous German chemist who falsely claimed that muscular energy comes from animal protein (2). This myth became so widely believed that it even helped shape the USDA's first recommendations for daily protein intake (3).
As discussed in The Plant-Based Advantage, we now know that hard-working muscles run primarily on glycogen, made from the carbohydrates found in plants, which also give our brain the glucose it needs to stay alert and on point during long and intense workouts and competitions.
While the benefits of a plant-based diet start with delayed fatigue and increased stamina, they also include decreased risk of joint pain and disease, increased aerobic fitness, improved immune function, and higher quality overall nutrition.
More than 40% of runners report “hitting the wall” during a marathon. This feeling of complete exhaustion happens when our liver and muscles run out of carbohydrates and is devastating to physical performance (4). Carbohydrate depletion also affect our brains, impairing concentration, coordination, and the ability to pace ourselves properly, while simultaneously making the same workload feel more difficult (5). These obstacles can make the difference between a successful workout or competition and major disappointment.
Since performance based eating patterns based on meat and other animal products typically provide dietary fat at the expense of carbohydrates (6-9), plant-based diets, which naturally contain ample carbohydrates, are much better suited to energy-intense performance sports and other activities (10).
As we also discussed in The Plant-Based Advantage, nitrate-packed vegetables make muscles more efficient and help preserve our limited fuel supply, which can significantly affect stamina. In one study, for example, simply adding beet juice allowed test subjects to cycle 22% longer than those in the control group (11).
Even without deliberately emphasizing nitrate-rich vegetables, eating plants has been shown to combat fatigue. In another study, recreational runners were able to shave 6% off their 5K run times just four days after switching to a plant-based diet. In this case, the researchers hypothesized that the anti-inflammatory nature of the antioxidant-rich plant foods also contributed to the faster run times (12).
The Plant-Based Advantage also explains how unchecked inflammation can not only prolong recovery times between workouts and competitions, but can also increase joint pain and risk of disease.
People who train or compete frequently, especially in endurance activities that rely upon thousands of repetitive motions (or, in the case of Scott Jurek’s 2200-mile run featured in The Game Changers, millions), are at higher risk of repetitive stress injuries and degenerative joint diseases (13-15).
Fortunately, diet can play a major role in how our bodies respond to this repetitive stress, either increasing inflammation or decreasing it.
As also discussed in The Plant-Based Advantage, the difference between the inflammatory effects of animal vs. plant foods is striking. In one study, for example, just one month on a low-carbohydrate animal-based diet increased inflammatory markers by 46%, while those on a high-carbohydrate plant-based diet decreased these same markers by 28% (16). Plant-based diets are not only associated with lower inflammatory markers (17), they're also linked to lower odds of joint pain. The difference between the two diets is so dramatic that eating meat as little as once per week has been linked to 43-49% higher rates of soft tissue disorders like tendinitis and degenerative arthritis than those who avoid meat (18).
Taking all of this into account, it’s little wonder why so many professional athletes are turning to plant-based diets, not only to increase their performance, but also to prolong their careers.
As we discuss in Getting and Staying Lean, plant-based diets have been shown to decrease body fat and the majority of those who follow them have a lower overall body fat percentage. The effects of lower body fat not only affect one’s appearance and general health, but also have a significant impact on endurance.
Much like running with a backpack weighs us down, carrying extra body fat for miles at a time can be taxing on the body. Endurance athletes of equal VO2 max (the maximum amount of oxygen you can utilize during exercise) but different body weights will not perform the same; the lighter athlete will demonstrate greater stamina and outperform the heavier one (19,20).
The same holds true for people who aren’t trained athletes, since weight loss has been shown to improve relative V02 max by 15% (21). And even without weight loss, a meat-free diet has been shown to decrease body fat and increase aerobic fitness (22).
While moderate exercise improves immunity, more rigorous training can actually lower immune function, putting high-performance athletes at increased risk of upper respiratory infections, including colds, flus and even pneumonia (23). And the stress doesn’t need to be physical; mental stress — experienced by competitive athletes and everyday people alike — can also lead to lowered immune function (24).
Once again, plant foods offer significant advantages, improving immune function through a variety of ways (25-27). Interestingly, one of these ways is by simply consuming more carbohydrates, which helps protect our immune system from hard exercise (28).
Another helpful plant-sourced ingredient is carotenoids, a class of antioxidants found abundantly in yellow, orange and red fruits and vegetables, which also enhance immunity (29). Beta-glucan, a type of fiber found in oats and numerous other grains, has also been shown to improve immune function, significantly reducing cold symptoms after a marathon for up to a month (30), while helping people under stress feel healthier and more energized (31). These, and other elements of plant-based diets, help explain why plant-based runners also experience allergies less frequently than people who eat meat and other animal products (32).
Whether you’re a high-performance athlete, worker, student, or parent, improved immunity means less time spent sick and more time training, competing, working, studying, or simply enjoying everyday life.
As we discussed in What About Protein?, endurance athletes require more protein than non-athletes, roughly 1.2-1.4 grams per kilogram of bodyweight per day (33). While many people might consider this a challenge to achieve on a plant-based diet, research has shown that endurance athletes who don’t consume meat get the same amount of protein per pound as those who do (34). Likewise, a cross-sectional study comparing vitamin B12 and vitamin D levels in recreational runners on plant- vs animal-based diets showed no significant differences (35).
High quality nutrition is about more than just protein and vitamins, since countless other nutrients contribute to how we feel and perform, including the pigments in vegetables, the polyphenols in fruits, and the phytochemicals in nuts, all of which improve exercise performance and accelerate recovery after training (10).
The abundance of health-promoting nutrients found in plants explain why, compared to their meat-eating counterparts, plant-based runners earn higher overall diet quality scores (33).
While the common misconception is that animal foods are required for optimized energy and stamina at both the physical and mental levels, the evidence shows that an animal-based diet tends to undermine these goals. Meanwhile a plant-based diet can offer numerous distinct benefits, not only helping to improve our energy and stamina, but also helping to protect our joints, increase our aerobic fitness, aid our immune systems, and improve our overall nutrition.
Given that even a 0.5-1.5% improvement in performance can make a critical difference in competitive sports (37), the compound effect of these plant-based benefits can be very significant, whether you’re an endurance athlete or someone simply looking to stay active and energized.
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Will I get enough energy? What about carbs? Our experts and athletes weigh in on the most commonly asked questions about plant-based eating and going the distance.View All