When you consume more protein than your body needs to supply its amino acid demands, the excess protein can be burned for energy. Your body burns molecules for energy using a series of chemical reactions known as the citric acid cycle. Excess amino acids can be turned into molecules that can be used in the citric acid cycle via a chemical process known as transamination. For example, some amino acids can be converted into the molecule acetyl CoA, an important molecule for the citric acid cycle. If you consume more protein than your body needs each day, the excess protein will be converted into body fat. Many athletes consume large amounts of protein to try to promote weight gain, but much of this added weight will be in the form of fat. In addition, consuming excessive amounts of protein can also affect the health of other parts of your body, esp kidneys.
A calorie is a calorie. Once you meet your basic nutrient needs it doesn't matter where the rest of your calories come from. If it's more energy than you need, you'll gain weight. The average adult only needs 0.8 grams of protein per kg body weight. If you are doing intense muscle building exercise raise that to 1 or 1.2. Otherwise any surplus protein just gets converted to fat. Keep in mind that you need to be eating carbohydrates in addition to protein. Your body needs a constant supply of glucose, mostly for brain function. If your body doesn't get this glucose from carbs it will break down the protein your feeding it instead. Not a huge deal..but a waste of expensive high-quality protein. I would suggest using the 0.8/kg body weight ratio to figure out how much you need. Dieters/exercisers tend to get obsessed with protein for some reason. All protien contains calories (Optimum protien shake 120 calories per shake).
