The CrossFit prescription for nutrition is:
Eat meat and vegetables, nuts and seeds, some fruit, little starch and no sugar. Keep intake to levels that will support exercise but not body fat.
The Caveman or Paleolithic Model for Nutrition
Modern diets are ill suited for our genetic composition. Evolution has not kept pace with advances in agriculture and food processing resulting in a plague of health problems for modern man. Coronary heart disease, diabetes, cancer, osteoporosis, obesity and psychological dysfunction have all been scientifically linked to a diet too high in refined or processed carbohydrate. The Paleo/Primal/Keto/Bulletproof Diets are perfectly consistent with the CrossFit prescription. The following books are a great start in learning about nutrition:
But if you are just starting out, we suggest NoSAG.
Food science and Paleo nutrition can become very complex topics, and so No SAG a simplified nutrition program that will work as a great starting point for people to make incredibly positive changes in their diets.
The No SAG prescription is to avoid all added sugar, alcohol, or grains of any kind. It's really that simple.
There are many positive changes in the body when gluten and sugars are removed, but the most obvious change is in body composition.