MYTH: Excess protein in the diet just gets excreted and cannot make you "fat"
THE SCIENCE: it is true the body's ability to store excess protein is limited. It is true that a portion of the protein is excreted in the urine (the nitrogen group i.e.: protein urea). However, the other portion(carbon group) is converted to fat or glucose depending on the body's current needs. Ultimately excess consumption has the same fate as other overconsumption of macronutrients fat or carbohydrate and that is the storage of fat.
Protein consumption ranges should be 15-35% of daily caloric consumption depending on activity. Plant based protein intakes need to be 10% higher for vegans. The most complete sources are whey, eggs, beef and soy providing both the essential and non essential amino acids required for complete protein. Other sources should be combined to meet requirements of all essential amino acids for example beans plus rice.
Heres a handy food list for combining foods to complete proteins
Legumes + Grains
Legumes + Nuts
Dairy + Grains
Legumes + Seeds
Below is a great graphic of servings of protein