It's very important. There are some people that say fitness is 80% and nutrition is 20%. I think it's more like 50-50. Nutrition is important but is not hard to follow because the American Dietetics Association basic recommendations are very well. For the high protein dieters I think that's fine, but first of all, it is clearly not necessary. There are many cases where somebody embarks on fitness and a physical life style. For example doing a low carbohydrate diet
is very difficult to do because the body does run on glycogen and carbohydrate.