When estimating a serving size, it is good to know that 3 oz. of is about the size of a deck of cards.

When estimating a serving size, it is good to know that 3 oz. of meat, poultry, or fish is about the size of a deck of cards. One should strive for two to three servings of meat per day for protein content. Be sure to watch fats, however, as some meats are fattier and therefore unhealthier than others.