The Recommended Dietary Allowance (RDA) for protein is a modest 0.8 grams of protein per kilogram of body weight. The RDA is the amount of a nutrient you need to meet your basic nutritional requirements. In a sense, it’s the minimum amount you need to keep from getting sick — not the specific amount you are supposed to eat every day.
To determine your RDA for protein, you can multiply your weight in pounds by 0.36, or use this online protein calculator. For a 50-year-old woman who weighs 140 pounds woman and who is sedentary (doesn’t exercise), that translates into 53 grams of protein a day.
But use of the RDA to set daily protein targets has actually caused a lot of confusion. “There’s a misunderstanding not only among the public, but also somewhat in our profession about the RDA,” says Nancy Rodriguez, a registered dietitian and professor of nutritional science at the University of Connecticut in Storrs. “People in general think we all eat too much protein.”
Rodriguez was among more than 40 nutrition scientists who gathered in Washington, D.C., for a “Protein Summit” to discuss research on protein and human health. The summit was organized and sponsored by beef, egg, and other animal-based food industry groups, but it also generated a set of scientific reports that were independently published a special supplement to the June issue of the American Journal of Clinical Nutrition (AJCN).
Protein: Is more better?
For a relatively active adult, eating enough protein to meet the RDA would supply as little as 10% of his or her total daily calories. In comparison, the average American consumes around 16% of his or her daily calories in the form of protein, from both plant and animal sources.
The Protein Summit reports in AJCN argue that 16% is anything but excessive. In fact, the reports suggest that Americans may eat too little protein, not too much. The potential benefits of higher protein intake, these researchers argue, include preserving muscle strength despite aging and maintaining a lean, fat-burning physique. Some studies described in the summit reports suggest that protein is more effective if you space it out over the day’s meals and snacks, rather than loading up at dinner like many Americans do.
Based on the totality of the research presented at the summit, Rodriguez estimates that taking in up to twice the RDA of protein “is a safe and good range to aim for.” This equates roughly to 15% to 25% of total daily calories, although it could be above or below this range depending on your age, sex, and activity level. That range fits nicely into the recommendation from the current Dietary Guidelines for Americans that we get 10% to 35% of daily calories from protein.
What should you do?
Research on the optimal amount of protein to eat for good health is ongoing, and is far from settled. The value of high-protein diets for weight loss or cardiovascular health, for example, remains controversial.
Before you start packing in more protein, there are a few important things to consider. For one, don’t read “get more protein” as “eat more meat.” Beef, poultry, and pork (as well as milk, cheese, and eggs) can certainly provide high-quality protein, but so can many plant foods — including whole grains, beans and other legumes, nuts, and vegetables. The table below provides some good sources of protein.
It’s also important to consider the protein “package” — the fats, carbohydrates, vitamins, minerals, and other nutrients that invariably come along with protein. Aim for protein sources low in saturated fat and processed carbohydrates and rich in many nutrients.
One more thing: if you increase protein, dietary arithmetic demands that you eat less of other things to keep your daily calorie intake steady. The switches you make can affect your nutrition, for better or for worse. For example, eating more protein instead of low-quality refined carbohydrates, like white bread and sweets, is a healthy choice — though how healthy the choice is also depends on the total protein package.
“If you are not eating much fish and you want to increase that — yes, that might improve the overall nutrient profile that would subsequently improve your health,” says registered dietitian Kathy McManus, director of the Department of Nutrition at Harvard-affiliated Brigham and Women’s Hospital. “But I think the data are pretty strong against significantly increasing red meat, and certainly processed meat, to get protein.”
If weight loss is your main concern, trying a higher-protein diet is reasonable, but don’t expect it to be a panacea. “Patients come to me all the time asking if more protein will help them in weight loss,” McManus says. “I tell them the verdict is still out. Some studies support it, some studies don’t.”
Good sources of protein
|3 ounces tuna, salmon, haddock, or trout||21|
|3 ounces cooked turkey or chicken||19|
|6 ounces plain Greek yogurt||17|
|½ cup cottage cheese||14|
|½ cup cooked beans||8|
|1 cup of milk||8|
|1 cup cooked pasta||8|
|¼ cup or 1 ounce of nuts (all types)||7|
|Source: USDA National Nutrient Database, 2015|