Q: What is protein and is it crucial to make sure I get enough?
A: Protein comprises 20 building blocks called amino acids. Of those 20, the body makes 11 called nonessential amino acids. The other nine, called essential amino acids, must be supplied by food, or dietary protein, explains Julie Burns, M.S., R.D., owner of SportFuel Inc., a sports-nutrition company in Western Springs, III.
There are two kinds of dietary protein -- complete and incomplete, Burns says. Animal and soy proteins are called "complete" proteins because they contain all nine essential amino acids. Plant products, including vegetables, nuts and legumes, are called "incomplete" proteins because they lack one or more essential amino acids, she says.
As a macronutrient, protein helps curb your appetite, which may help you lose weight. Compared to carbs and fats -- which are primarily energy sources -- proteins play crucial roles in the body. They provide structural features of body tissue and serve as immune-system antibodies/signaling molecules. In the form of enzymes and hormones, proteins help regulate sleep, digestion and ovulation.
For these functions and others, your body requires complete proteins. However, by combining a variety of plant products throughout the day or over the course of a few clays, you can easily satisfy your body's needs without eating meat or soy products, Burns says. If you're a vegetarian or vegan, eat combinations of plant proteins that complement each other, such as rice and beans, peanut butter and bread, or hummus and pita.
Q: I've heard some forms of protein are "superior." Is that true?
A: Just because animal protein is complete doesn't mean it's healthier than incomplete plant proteins, Burns says. Sources of animal protein are usually higher in fat, particularly saturated fat, and lower in fiber than plant-based sources, although there are plenty of lean complete proteins: seafood, lean beef, pork tenderloin, the breast meat of poultry, nonfat milk and egg whites are a few examples, says Burns. Plant sources of protein, on the other hand, don't contain saturated fat, are always cholesterol-free and have lots of disease-fighting phytochemicals.
Q: How much protein do I really need to eat every day?
A: If you're mildly active (you exercise three times a week for 30-60 minutes), you probably don't need more than the RDA -- 0.4 grams per pound of ideal body weight, says Melinda Manore, Ph.D. To calculate your daily protein needs in grams, multiply your weight by 0.4. (For a 145-pound woman, that's 58 grams, or 12-15 percent of total daily calories.)
If you're moderately active (you exercise four to six days a week for 30-60 minutes), you may need slightly more -- from 0.6-0.7 grams. (That's 87-101.5 grams, or about 20 percent of total daily calories, for a 145-pound woman.)
If you're highly active (you exercise daily for an hour or more) you may need even more protein than that -- from 0.9-1 gram. (For a 145-pound woman, that's 130.5-145 grams, or about 30 percent of total daily calories.)
You also may need this amount if you are recovering from a serious illness or exercising at higher altitudes than usual -- for example, you're backpacking at 7,000 feet but live at sea level. At higher altitudes, your body is deprived of oxygen until you adapt, placing a stress on all systems and increasing cellular damage. Protein helps protect and repair cells while your body acclimates, which can take several weeks.
Q: Is it a problem if my protein intake is higher than the RDA?
A: If you consume more protein than you really need, you risk several negative consequences. First, you could gain weight. Consuming more calories than you need in a day, even if they're protein calories, will cause your body to store the extra calories as fat.
In addition, eating protein at the expense of vegetables, grains and other healthy foods can deprive your body of essential nutrients. Plus, it can cause dehydration because it takes a lot of water to eliminate extra protein.
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