WATCH: Eat Like an Olympian with Vegan Ultra-Endurance Athlete Rich Roll

The 2016 Olympics may not officially kick off until tonight, but there is already a group of winners from Team USA! Tennis stars Venus and Serena Williams, beach volleyball gold-medal favorite April Ross, and weightlifter Kendrick Farris are a few of the growing number of American athletes powering their performances with plant-based foods.

More and more athletes are finding that a plant-based diet can easily provide all of the necessary vitamins, minerals, and yes—even protein—to fuel a medal-winning performance.

"I believe in the power of plant-based eating, and as an athlete, I always need to feel my best," says Venus Williams, who fuels her victories with green smoothies, brown rice, quinoa, tons of fresh vegetables, and even vegan pizza.

Australian sprinter Morgan Mitchell made the switch to a vegan diet two years before she made the trip to Rio—much to the dismay of her coaches and teammates. But after an initial learning curve, Morgan reports that she began to feel “lighter and cleaner” and her sprinting times immediately improved.

Curious about how it all works? This week, the Physicians Committee is teaming up with ultra-endurance athlete Rich Roll, who was named one of the “25 Fittest Men in the World” by Men’s Fitness, to show how powerful plant-based nutrition is for athletes. Rich, fueled entirely by plants, is widely famed for being the first person to complete five Ironman-distance triathlons on five Hawaiian islands in less than a week.

In a new video, Rich joins the Physicians Committee’s Karen Smith, R.D.—the fastest Delaware woman to run the 2016 Boston Marathon—to talk about some of their favorite foods to fuel athletic performance.

Get the recipes for Rich’s Superfood Energy Balls, Veggie Burgers, One Bowls, and Epic5 Smoothies from Rich’s book The Plantpower Way.