Q: I am a 29-year-old woman and have been training hard for several years now. I want to take my body to the next level. How much protein do I need to consume to achieve my goal?
Well, if you go by the Recommended Dietary Allowances (RDA) espoused by the United States Department of Agriculture, it’s 46 grams daily – a modest 0.8 grams of protein per kilogram of bodyweight. The RDA, however, has a major flaw in its design: it bases protein requirements on the average couch potato. While this is fine if you want to be average, it has little relevance if you are a hard-training fitness enthusiast. In truth, those who aspire to optimize body composition require significantly more protein than what is prescribed in the RDA.
For active individuals, especially those involved in strength-training regimens, studies have consistently shown optimal intake to be about eight-tenths of a gram of protein per pound of bodyweight. The reasons are twofold: first, during exercise, amino acids are oxidized for fuel at an accelerated rate. Depending on the intensity and duration of training, these amino acids can supply up to 10 percent of the body’s energy needs. What’s more, the stresses associated with physical activity cause an increased breakdown of body proteins, leaving the body in a catabolic state. The only way to reverse these effects and promote an anabolic environment is by consuming additional dietary protein, over and above RDA guidelines. Abide by the RDA, and you’ll surely be in a negative nitrogen balance (i.e., your body is breaking down proteins at a greater rate than it’s synthesizing them).
A protein-rich diet also confers specific metabolic benefits. For one, a large percentage of calories from protein are burned off in the digestion process – a phenomenon called the thermic effect of food (TEF). Of all the macronutrients, protein has the highest thermic effect, burning off approximately 25 percent of the calories consumed. In comparison, only 10 percent of the calories from carbs are burned off in digestion; fat has virtually no thermic effect whatsoever. When the TEF is factored into a mixed meal, higher intakes of protein can as much as double postprandial thermogenesis (the number of calories burned after eating), leaving fewer calories available to be stored as fat.
Further, protein tends to curb appetite. During its digestion, protein potentiates the secretion of a hormone called cholecystokinin (CCK), which acts to suppress the body’s hunger mechanisms. These satiety-inducing effects are pronounced, lasting several hours after a meal. And when appetite isn’t driven by hunger, food choices can more easily be made based on rationale rather than impulse. This is why studies have consistently shown that when people are left to make their own nutritional decisions (called an ad libitum diet), those who consume high amounts of protein take in significantly fewer calories than those who don’t eat lots of protein.
Lastly, protein is “insulin friendly.” You see, insulin acts as a storage hormone. While its primary purpose is to neutralize blood sugar, insulin is also responsible for shuttling fat into fat cells. As insulin levels rise, so does the potential for fat deposition. Protein, however, has only a modest impact on insulin secretion. In fact, certain amino acids stimulate the release of glucagon, a hormone that opposes insulin and keeps it in check. The end result: your body is more apt to burn fat than to store it.
A higher protein intake is especially important when you are restricting calories (if the goal is weight loss). During stringent dieting, there is a tendency for your body to break down protein stores into glucose (through a process called gluconeogenesis) so that the brain and other tissues have adequate fuel. Since skeletal muscle is not necessary for sustenance (as opposed to the internal organs and other protein-based tissues), it is the primary bodily tissue to be cannibalized. The only way to counteract this occurrence is by consuming extra protein. Keeping protein intake high helps to preserve lean tissue, preventing the negative consequences of muscle wasting.
Taking all factors into account, my recommendation is to consume approximately 1 gram of protein per pound of bodyweight. This provides a margin of safety, ensuring you never fall into negative nitrogen balance. There really is no downside to the approach – taking in a little extra protein won’t hurt; not getting enough surely will.