It's not about protein quantity, it's about *quality*

Each product we feature has been independently selected and reviewed by our editorial team. If you make a purchase using the links included, we may earn commission.
Getty Images

When you're meat-free and a gym rat, you're used to a barrage of people trying to convince you you're not getting enough protein. Truth is, you probably have your daily count under control (soy milk! Quinoa!). But exercise scientists are urging vegetarians-particularly vegans-to start asking a different question: Am I getting the right kind of protein?

"Plant-based proteins are very low in essential amino acids, and without animal or dairy-based protein, it's harder for vegetarians and vegans to get a quality supply of nutrients," says Jacob Wilson, Ph.D., director of the Human Performance and Sports Nutrition Lab at the University of Tampa.

The 21 crucial amino acids-most of which your body produces-are the building blocks of protein. And to stimulate protein synthesis-which turns on the muscle building effect-your amino acid levels need to reach a certain threshold. Without both a high enough level and enough varieties of amino acids, your muscle-building potential is stifled, explains Wilson.

Why does this matter most for vegetarians and vegans? The richest sources of the nine essential amino acids that your body can't produce are animal-based proteins, like red meat, chicken, eggs, and dairy. Three of those nine are branched-chain amino acids (BCAA) and are particularly important for workout recovery. Your post-workout shake might take care of the problem: If plant eaters consume high-quality protein powders, like whey and soy, which have all nine compounds, there's no concern, Wilson says. (Shop for whey protein to find your flavor and type at GNC Live Well.) The complication comes when food allergies and diet restrictions make it such that whey and soy may not be an option.

You're also not doomed on a plant-based diet. Certain plant proteins are "complete," meaning they contain all nine essential amino acids in a single food. The most obtainable of these are quinoa, hempseeds, chia seeds, and soy.

Incomplete proteins, though, are a bit more complicated: "Most plant-based proteins are not void of all essential amino acids, just certain ones, and which ones vary from food to food," says Brad Schoenfeld, Ph.D., director of the Human Performance Lab at the City University of New York. "You have to combine plant proteins strategically throughout the day to provide a complete fill of all essential amino acids."

Beans, for example, are low in the amino acid lysine, but paired with lysine-rich rice allows a meal of the two to become a complete protein source. Other ace combinations include hummus and pita, peanut butter and whole wheat bread, and tofu and rice-all of which provide all nine essential amino acids when paired together. And you don't have to eat the pair all in the same meal. Your body holds a reserve of amino acids, so you can have beans for breakfast and rice for lunch, Schoenfeld adds.

So is it possible to gain enough amino acids from a plant-based diet? Yes, says Schoenfeld. But one meal of complete protein in a day isn't enough to keep your reserves up. That means unless you're actively monitoring what proteins you're eating and are conscious of their chemical makeup, maintaining an adequate and comprehensive amino acid pool can be hard to keep up with-especially if you're active and have muscles with a higher amino acid demand, he adds.

Stocking Up with Protein Supplements

If you're a vegan, soy-free, and dairy-free, or slack on pairing your plant-based protein sources, consider trying an amino acid supplement once a day for a few weeks (there's little harm in ingesting extra amino acids, researchers assure).

Both Schoenfeld and Wilson-along with most researchers-agree that supplementing will help keep your muscles from breaking down. Women in a 2010 Japanese study who took BCAA supplements before a workout recovered from post-gym muscle soreness faster in the following hours and days. A 2011 Brazilian study found that 300 milligrams of BCAA increased the amount of oxygen in participants' bloodstream, helping them feel less tired after an exhaustive workout.

The best way to add amino acid supplements to your diet?

Supplement post-workout: Most studies show the best results when participants add amino acids in after a workout. The most important time to replenish is if you sweat at sunrise, Wilson says. If you run or workout in a fasted state, afterward your body is trying to recover on nothing until you replenish it with protein and amino acids.

Look for leucine: Researchers from the U.S. Army Research Institute of Environmental Medicine found that when participants took a leucine-rich essential amino acid supplement (versus the basic) during a 60 minute bike ride, their muscle protein synthesis increased by 33 percent. MusclePharm's Amino 1 has a great balance of amino acids, and comes in smaller sizes for your trail period ($18 for 15 servings,