I hear this question a lot, especially since I advocate higher protein diets. I've had some anti-protein nazis fight me on this one, saying that we get way too much protein in our American diet as it is. Well guess what? The vast majority of Americans get way too much of EVERYTHING in their diets, so this isn't a surprise. But if you're going to target macronutrients to cut down on, protein is the last one to target.So does excessive protein lead to weight gain? Of course. Your body converts excess protein and stores it as fat. Is protein more taxing on the body to digest? Yes, for several reasons. One of them is because of the nitrogen-based waste products can tax the kidneys. But really now, this isn't the end of the world. Fats, alcohol, and fructose in large quantities are also taxing on the body, in this case the liver.
The one thing you must prevent is the breakdown of your muscle tissue. You work too hard at the gym for your muscles. If you aren't getting enough protein, your body breaks down your functional muscle tissues and consumes the amino acids found there. Plus, if you're constantly breaking down muscle (as you should be during resistance training) you're going to need more proteins overall.
So in short, I recommend at least 1g per kg body weight per day, and up to 2g. The quality of the protein is also important. Protein quality refers to the usability of the amino acids making up the protein. Animal proteins are more usable than plant proteins. The rule "the less legs the better" will give you a simple way to rate your proteins for usability and fat content. Seafood would be the best, with chicken next and pork and beef third. Plant proteins need to be consumed in the right combinations (such as rice and beans) to get all the essential amino acids. Though less usable than animal protein, soy has all the essential amino acids, but the phytoestrogen content of soy may make it unhealthy as a regular source of protein.
The bottom line is you need to eat. If you replace some of the excess fat and refined sugar with lean protein, then all the better. Besides, if you're deficient in protein, you lose vital muscle. If you're deficient in sugar or fat, you burn stored fat... I'd clearly rather burned stored fat from undereating than muscle.
