Along with being delicious, beef contains important nutrients that your body needs. The recommended serving size is 4 ounces for raw beef (about the size of a deck of cards), which translates to about 3 ounces of cooked beef. Beef delivers 10 essential nutrients; on average, a 3-ounce serving of cooked beef provides 175 calories and protein (51% DV), B12 (41% DV), zinc (39% DV), selenium (38% DV), niacin (25% DV), B6 (24% DV), phosphorous (20% DV), riboflavin (14% DV), iron (14% DV) and choline (13% DV). DV refers to Daily Value, the amount of nutrient needed for a healthy adult on a 2,000 calorie diet.