Kristina Carillo-Bucaram runs six to eight miles a day, and she eats nothing but raw vegetables and fruits.
"I eat about 3,000 calories a day," Carillo-Bucaram said.
She says that's enough to provide energy for running. Before the raw diet, where she eats nothing that is cooked, she was underweight.
"I was very sick all the time, I was nauseous. I almost didn't graduate from high school from having so many sick days," Carillo-Bucaram said.
Arian Foster of the Texans recently announced he was going vegan, a diet where you can eat cooked vegetables, but no products from animals, meaning no milk or cheese. But athletes can't just drop all protein.
"Our body needs protein in order to build and maintain our muscles, our lean mass. And you've got to remember our heart is also a muscle," said Dr. Penny Wilson with the Ironman Sports Medicine Institute at Memorial Hermann.
Could going vegan affect Foster's game?
"It could be that he starts potentially getting some injuries and it could also be that he doesn't play as well because he's not recovering," Wilson said.
So they must get protein elsewhere.
"A cup of beans, any one of these, is about the same amount of protein as two ounces of meat," Wilson said.
Oatmeal, spaghetti, lentils, soy, tofu and vegan burgers all have protein. But Wilson warns it takes extra time to plan and cook meals when you're replacing protein. And you should ease into a vegan diet, or you could face cramps and gastrointestinal problems.
Dr. Wilson says if you're going on a vegan diet, it's best to do it slowly. She suggests going vegan for one meal a day, then adding meals until your body adjusts. Going off a vegan diet suddenly can also cause GI problems.