The National Academy of Sciences Dietary Reference Intakes (DRIs) are widely accepted as the most authoritative source for defining nutritional requirements. The DRIs are the basis for the more commonly recognized recommendations from the USDA, known as the Dietary Guidelines for Americans, and translated for the public as My Plate. The DRIs define the Recommended Dietary Allowance (RDA) for a wide range of micronutrients (vitamins and minerals), and also for protein and carbohydrate (but not for fat). In addition, the DRIs express the recommended dietary intakes of protein, carbohydrate, and fat in terms of a percentage of total caloric intake.
The Recommended Dietary Allowance (RDA)
The RDA for protein is 0.8 grams for every 2.2 pounds of body weight. So, a 175-pound person needs to eat about 63-65 grams of protein (or 2.2 ounces) per day to meet the RDA.
The average American eats approximately 4-5 ounces of protein per day, or about twice the RDA. This may seem like a small amount of protein considering you’ve got a 10-ounce steak on the menu for dinner tonight. However, it is important to distinguish the intake of pure protein, reflected by dietary guidelines, from protein food sources.
Even a high-quality protein food source like meat is not pure protein. There are approximately 7 grams of protein in 1 ounce of meat, so a 175-pound person can indeed satisfy the RDA for protein by eating a 9-ounce steak. However, there are many sources of protein in the diet, many of which have less protein per gram than steak does. If you add up all protein food sources you eat in the day, including perhaps eggs, yogurt, or cereal with milk for breakfast, some ice cream or pudding for dessert after lunch, and a dinner with fish, chicken, or meat, you are probably eating at least twice the RDA for protein. Add to the obvious protein food sources the amount of protein in foods like wheat, peas, potatoes, soy, etc., and you are likely eating quite a bit more than the RDA.
Does eating more protein than the RDA suggests lead to health issues like obesity and diabetes? Some doctors and health professionals believe so. Who hasn’t heard the admonition to quit eating red meat? However, you must remember that the RDA is defined as the minimum amount that should be eaten to maintain body protein—that’s the lowest dietary protein intake at which the rates of protein synthesis and breakdown are theoretically matched throughout the day. As for sticking to this minimum…well, there has never been a study with health outcomes that has shown that eating the RDA for protein is preferable to eating a greater amount of protein.
Dietary Protein Intake as a Percent of Total Calories
In addition to the RDA, the DRIs also recommend that protein intake falls within a certain percentage of total caloric intake. Since all the food we eat is in the form of three macronutrients—carbohydrate, fat, and protein (four if you include alcohol)—the DRIs committee accounted for the fact that the amount of each macronutrient eaten will influence the amount of the other macronutrients in the diet.
For example, if you eat a high-protein diet, you are, at the same time, decreasing the amount of fat and/or carbohydrate that you eat. Recommended ranges of calorie intake for each macronutrient were set to account for this interrelationship. The DRIs recommend that dietary protein constitutes between 10-35% of dietary caloric intake. They also state that there is no evidence of harmful effects for intakes above this level. For the average-size, non-active person, the RDA for protein provides about 10% of the caloric intake in a day, the lower limit of the range for protein. A diet providing 3.5 times more protein is still within the recommendations of the DRIs.
A recommendation of dietary protein intake with a range of 3.5 times (or more) can hardly be considered a useful guideline. Consequently, we have to accept that the “experts” have let us down as far as giving us concrete guidelines for dietary protein intake. We need to figure this out for ourselves. The place to start is to understand the difference between the optimal as opposed to the minimal amount of protein intake.
Minimal vs. Optimal Protein Consumption
The RDA for protein corresponds to about 10% of daily caloric intake. This is the minimal amount of protein you need to avoid losing muscle mass. Since the RDA is only equivalent to about 10% of dietary calories, you might consider protein content a minor component of diet. This perspective is missing the boat. Protein should take center stage in most every person’s diet. There is a particularly good argument for the centrality of protein in an athlete’s diet, in terms of both muscle mass and strength. More generally, dietary protein has a central role in the nutritional arsenal against the chronic diseases and stress many of us deal with every day. Many of these beneficial effects are also related to dietary protein’s influence on muscle. The starting point of good nutrition to improve physical health and performance is a balanced diet that contains the optimal amount of protein, rather than the minimal amount of dietary protein.
When it comes to answering the question how much protein should I eat all data points to the optimal level of protein intake being greater than the RDA of 10% of caloric intake.
The average American eats about 20% of caloric intake, which is a reasonable amount. While consuming more protein may provide further benefits, the total amount of calories from protein food sources makes greater protein intake difficult to accomplish in the context of a balanced diet. That’s where amino acid supplementation can come in handy. The potential role of essential amino acid supplements in achieving optimal protein intake becomes evident when you consider that supplements provide the active components of dietary proteins without the accompanying non-protein components (carbs and fats). Learn more about the best high-protein foods to eat and amino acid nutrition here.