Protein is an essential nutrient in the diet. Typically 0.7g per kg bodyweight of protein per day is recommended to ensure you get enough in your diet. This intake increases for those people who exercise and varies for the type of exercise you are doing. Protein needs for endurance athletes are 1.2 -1.4 g/kg and 1.4-1.8 g/kg for strength and power athletes. Some bodybuilders may take 2-3 g/kg of protein per day but studies have shown that these higher levels do not result in further muscle mass and strength gain beyond that which is achieved with the recommended intake. With strength training you need approximately double protein intake of a sedentary person, but when your intake limit is reached, then additional protein will not be converted into muscle.
Firstly, part of the protein is converted to urea in the liver which is excreted in the urine. Next, the rest of the protein molecule is converted to glucose which can either be used as a fuel for energy or be stored as glycogen. However, if you are already consuming adequate carbohydrate in your diet and your glycogen stores are full then the excess protein can be converted into fat by the body.
Conversion of protein to fat does not occur to a huge extent. Eating protein is associated with an increase in metabolic rate so most of the protein calories will be given off as heat. It is the excess calories from fat and carbohydrates that are associated with weight gain due to stored fat increases. Certain risks such as dehydration, liver & kidney damage and osteoporosis have been associated with high protein diets in the past but these claims are largely unfounded. However, long term adherence to a high protein diet is not ideal and will offer no advantages for strength and muscle mass beyond a certain intake.
Please feel free to contact the G4 Didsbury Clinic (Manchester) to speak to a member of our diet & nutrition team for any questions that you may have or if you wish to arrange a consultation to discuss your diet, nutrition and lifestyle.