On average, Americans eat far too much protein. The current recommendation is that proteins make up around 15-20 percent of your total calories for the day. Protein has four calories per gram, so for a 2000 calorie-a-day diet you could eat 75-100 grams of protein. However, most of us consume more than that. Eating too much protein is damaging to your body.

A more accurate way of calculating protein needs is to allow 0.36g of protein per pound of body weight, or 0.36g per pound. For example, 135 lb person would need 48g of protein per day. Growing children need about one gram of protein for every two pounds of body weight. For example, a 56 lb child needs about 28 grams of protein a day to sustain her growth.