You already know you should eat healthy stuff, but maybe you'd like some specific advice straight from the mouth of a BJJ legend. After a student asked him which types of food are suitable for jiu-jitsu, Rickson Gracie provided just that.
"Jiu-jitsu demands from you a lot of effort, physically—you sweat a lot, you tear ligaments—so you have to have a good nutritional-value diet," he said. "Clean proteins, if you eat beef and meat—very clean. Vegetables, superfoods, supplements like glucosamin, calcium, [?]—all the valuable nutrients for you to keep a healthy lifestyle.
"I love superfoods; I love bee pollen, I love spirulina, I love quinoas in my meals, sweet potatoes, clean carbohydrates. Stay away from sugars. Everything that comes in a box: stay away. Stay more in the natural food environment, cooking fresh food. Health comes in through your mouth; and if you eat poorly, you're not gonna have results in your body. So you have to eat healthy stuff, and definitely, your body will thank you, and your jiu-jitsu also."