How much protein do we need?
The recommended dietary allowance (RDA) for protein is 0.8 grams per kilogram of bodyweight—that’s about 46 grams per day for a woman and 56 grams per day for a man. However, that number could vary wildly depending on your daily caloric intake and physical activity. “If you’re strength training, your body requires more protein than the average person in order to repair muscle that’s broken down during training and build new muscle tissue,” says Lisa Davis, PhD, chief nutrition officer at Terra’s Kitchen. “The average weight lifter may need 1 gram of protein per kilogram of body weight, whereas a professional bodybuilder may need 1.5 grams per kilogram of body weight. (Here’s what could happen if you don’t eat enough protein.)
Soybeans have a high protein profile—just one cup, roasted, has a whopping 43 grams. Soy also comes in the form of soy milk, tempeh, miso, and tofu. “Firm tofu packs 10 grams of protein per half-cup, and the firmer the better when it comes to amount of protein,” says Dr. Davis. Soy is also rich in magnesium, a nutrient needed for energy metabolism, especially when you’re pumping iron (or any weight-bearing exercise) to build muscle. It also plays a vital role in muscle growth and repair. In fact, magnesium is so key to muscle building that some research suggests taking supplements when you’re doing resistance training to help increase strength further, according to Krissy Kendall, PhD, of bodybuilding.com. “Low levels can lead to fatigue, lethargy, reduced powered output, and muscle cramps,” she adds.