The same should be said about Carbs. ppl crack me up with this 'no carb" shit. there is a difference between the Carbs he needs to have energy to be able to go to the gym and bs empty carbs that fuk you up.
Stay away from Carbs from, white bread, white rice, sugar (no fukkn sugar unless it comes from fruit), pasta (unless whole grain). beer (hard one), soda. you get the idea.
eat Carbs from whole grains. oatmeal, brown rice, wheat bread, A good way to realize they the Carbs you want is they are generally high in dietary fiber.
If you are going about things right and putting in work in the gym you have to have Carbs, i guess there some diets that say "no carbs" and maybe they work but i doubt it has the long term effects a lifestyle change will have.