Why You Might Want to Ignore the Recommended Daily Allowance for Protein
At this point, you've heard that protein plays a role in muscle gain. What's not always so clear is whether high-protein diets are beneficial to everyone—or only athletes and serious weightlifters. A recent study published in Advances in Nutrition might have an answer.
Two groups of people, in particular, seem to benefit from surpassing the recommended daily allowance (RDA) of protein. (More on exactly how much that is, below.) Researchers looked at 18 existing studies that compared adults who consumed the RDA of protein with adults who exceeded the guideline. They found that in each case, people in the higher protein consumption group were more likely to gain or hold on to lean muscle mass than those in the other RDA group.
Before you order a burger, there's a caveat: Exceeding the RDA only proved to be beneficial for people who are A) limiting their overall calorie intake or B) incorporating resistance training. More specifically, the researchers found that people who were restricting their calories were less likely to lose lean muscle mass if they exceded the RDA of protein, and people who were practicing resistance training were more likely to gain lean muscle mass when exceeding the RDA. But for people who weren't cutting calories or resistance training, overshooting the RDA didn't make a difference in their lean muscle.
What is the Recommended Daily Allowance for protein?
The Institute of Medicine sets the RDA for protein in the U.S., and right now it's at 0.8 grams per kilogram of body weight (about 0.8 grams per 2.2 pounds). That means someone who weighs 150 pounds is advised to consume about 54 grams of protein per day. The National Institutes of Health defines RDA as the "average daily level of intake sufficient to meet the nutrient requirements of nearly all (97-98 percent) healthy people." So it's not presented as an ideal amount for everyone, but a general guideline based on the average healthy person.
In this latest study, however, the study authors wrote that their results show that "under stressful conditions such as energy restriction (ER) and physical activity, the RDA for protein may no longer be an appropriate recommendation." (Related: Who Should Eat a High-Protein Diet?)
How much protein should you eat if you're strength training?
Many registered dietitians are already suggesting a protein goal above the RDA to their active clients. "Registered dieticians know that there are different recommendations of protein based on various types and levels of physical activity," says Susan Wilson, R.D.N., L.D.N., president of the Kentucky Academy of Nutrition and Dietetics. "For those who are doing frequent resistance or weight training, the need can go up as high as around 1.7 grams per kilogram of body weight." Some dieticians advise clients who are serious athletes to consume 2 grams per kilogram of body weight during intense training, she says. But even cardio bunnies need more protein than the average recommendation. "Even doing a more aerobic type of activity increases the need for protein," says Wilson. "Typically, the recommendations are 1.0-1.2 grams per kilogram for light activity and 1.5 for moderate activity, like resistance training with lighter weight and higher reps."
How much protein should you eat if you're trying to lose weight?
Calculating the ideal amount of protein while cutting calories is a little more complex. "Typically I like to recommend that 10 to 15 percent of the total calories consumed comes from protein for the average person," says Wilson. A lot of factors play into how many calories you should consume when trying to lose weight, though, like your activity level and the timeframe you're trying to lose weight within. Wilson warns against playing around with these numbers too much if you aren't versed in nutrition. "Screwing around with your metabolism when you really don't know what you're doing and not under the guidance of a knowledgeable health professional can have some unintended consequences, not only for the number on your scale but possibly for your overall health as well," she says. (Related: 20 High-Protein Recipes That'll Fill You Up)
Is there such a thing as eating too much protein?
In either case, you want to avoid going too far over the RDA, since consuming too much protein carries risks. Protein is filtered through the kidneys, so excess protein can cause problems for people with kidney issues. A less scary risk is unintended weight gain. "If you're consuming more protein than your body needs, your body may choose to store that energy for future use," says Wilson. Meaning, yep, it gets stored as fat.
Bottom line: Your protein needs will largely depend on how you're eating and exercising, and what your goals are. If you're cutting or workout out often, you can probably benefit from exceeding the RDA for protein.