1) Eating very little or excessive protein.
Protein is the key nutrient in any bodybuilding diet plan. In order to build muscle one should consume at least 1 gram of protein per pound of lean bodyweight. Less protein can actually hinder one's progress significantly and result in frustration and lack of results. On the other hand excessive protein calories in a diet can be stored as body fat or in some cases used as energy. One gram per pound of lean bodyweight spread over 6 nutritious meals is a great starting point. If you want to build more muscle or you train harder OR you find that you are not recovering as fast you can slowly increase your protein intake to 1.1 grams per pound or 1.25 grams. Protein is the building block for muscle tissue and if you want to build mass OR get ripped you have to start eating more.
2) Eating the wrong types of carbs.
This is one of the most common nutritional mistakes I come across. I see people who want to add muscle and they eat anything for carbs, from chocolate bars & donuts to rice & potatoes! Fact of the matter is, not all carbs are created equal and you will be what you eat, eventually! Most people tend to overeat simple carbs (sugars) which give them an almost immediate rise in energy but also an equally sudden slump. A proper bodybuilding diet, whether it's for mass gaining purposes or leaning out, should consist mostly of complex carbs. Complex carbs are digested slowly and released into the bloodstream steadily over a period of time. This provides a steady source of energy for muscles throughout the day. With complex carbs there are no highs and lows in energy as they stay steady throughout the day.
