You should keep aiming for that 1,500-a-day calorie count, and make sure you're eating enough protein. By the time you reach 50, you don't process it as well as you did in previous decades, so you have to exceed the recommended daily amount of 46 grams. A UTMB study found that eating 4 ounces of protein-rich food per meal (as opposed to eating 12 ounces all in one sitting) maximizes your body's muscle-building rate by up to 50 percent. The news also appears on ABC News.