Determining how much protein an adult should consume each day might seem confusing. According to the Institute of Medicine, which sets nutrition recommendations, a healthy adult should consume anywhere from 10 to 35 percent of total calories in protein per day. That’s a big range. The average American diet amounts to about 15 percent protein, or about 75 grams a day for those on a 2,000 calorie-a-day diet.
Additionally, the Institute of Medicine advises that adults should eat a minimum of 0.8 grams of protein per kilogram (or 0.37 grams per pound) of ideal body weight. For a person whose ideal weight is 160 pounds, for example, that would be a minimum of about 60 grams of protein.
Paying attention to both pieces of guidance is important — particularly if you’re severely restricting calories for weight loss. If you’re eating, say, 1,200 calories a day, and you’re keeping your protein to the minimum of 10 percent of total calories, you’d only be consuming 30 grams of protein a day (each gram of protein has 4 calories). That’s not nearly enough for most adults. You’ll want to eat a higher percentage of protein and trim back one or both of the other macronutrients, carbohydrates and fat.
Note that when you make shifts in one macronutrient, it affects the percentages you’re consuming in the whole diet. Total fat should be limited to 30 percent of total calories, with most coming from healthier unsaturated types. For carbohydrates, the recommended range is 45 to 65 percent of total calories, with half coming from healthier whole grains. A minimum intake of 130 grams of carbohydrates per day is necessary for normal brain function.
For protein, the best choices include meats with relatively little fat, including lean beef, pork and poultry; fish, including salmon, trout and other choices high in omega-3 fatty acids; and beans, peas, soy products and unsalted nuts. For more detail, see the advice for protein in the 2010 Dietary Guidelines for Americans at http://bit.ly/chooseprotein.
If you’re trying to lose weight, you might have noticed that many mainstream diet plans recommend a higher proportion of dietary protein. And it’s true that protein helps with satiety, that feeling of fullness after eating. So, if you’re stuck in your attempt at losing weight, you might consider bumping up your lean protein intake while reducing carbohydrates, as long as you stay in the overall guidelines. That said, a 2009 study published in the New England Journal of Medicine comparing different regimens showed restricting calories overall was the key to weight loss, not where the calories come from.