Q: As a fairly new vegetarian, I'm not sure I'm getting enough protein. Is there a formula to figure out how much I need, and is age ever a factor?

A: Protein is the major component of all of your body's cells, and you're right, it's important to make sure you're getting enough. Recent research indicates that we may need more than previously thought. The recommended dietary allowance (RDA) for all adults is 0.37 grams of protein per pound of body weight, or about 15 percent of your daily calories.

But you probably need more if you exercise, if you're dieting and as you age. One dramatic study of 855 people found that those who ate just the RDA of protein had alarming bone losses compared to those who ate more than the RDA. Those who ate the least protein lost the most bone mass—4 percent in four years. People who ate the most protein (about 20 percent of calories) had the smallest losses-less than 1.5 percent in four years, reported the Journal of Bone and Mineral Research in 2000. Although the study was done on older men and women, the results may be important for all adults. "When you're young, you need protein to build bone. After age 30, you need it to keep bone from being lost," says Kathleen Tucker, associate professor of Nutritional Epidemiology at Tufts University. "Keeping bones strong is a life-long effort."

Dieters, take note: New research has found that a protein-dense diet may be essential for weight loss. It helps maximize fat loss while minimizing muscle loss. That's important because "losing muscle slows your resting metabolic rate—the speed at which your body burns calories. That makes it harder to maintain a healthy weight and lose fat," says William Evans, director of the Nutrition, Metabolism, and Exercise Laboratory at the Donald W. Reynolds Center on Aging at the University of Arkansas for Medical Sciences.

Many of us don't get the RDA for protein. Roughly 25 percent of adults over age 20, and 40 percent of those age 70 and up, fall below it, according to United States Department of Agriculture (USDA) statistics, let alone eat enough to protect bones or muscle. And thin women, dieting women and elderly women—who are especially vulnerable to the ravages of bone and muscle loss—are notoriously low on protein. "Losing muscle causes older people to become weak and frail," says Evans.

"It seems pretty clear that older adults may need more protein," agrees dietitian Reed Mangels, nutrition advisor to the Vegetarian Resource Group and co-author of The Dietitian's Guide to Vegetarian Diets. "Older vegetarians need to concentrate on eating protein-dense foods, such as legumes and soy."

Based on the new findings, I now recommend that moderately active people and older adults increase their protein to about 20 percent of their calories, or 0.45–0.54 grams per pound of ideal body weight. For what this means in real food, see below. If you're an athlete or body builder, you may need even more. On an individual basis, you can use the following formula to figure out your protein needs.

What You Need

You can figure out your own recommended dietary allowance (RDA) for protein. Just grab a calculator, and multiply your ideal weight by 0.37 grams of protein. So if your ideal weight is 150 pounds:

150 lb. x 0.37 grams protein = 56 grams of protein per day

But for active people and older adults, calculate 0.45–0.54 grams of protein per pound of body weight. So, if you're moderately active and your ideal weight is about 150:

• 150 lb. x 0.45 grams protein = 68 grams of protein
• 150 lb. x 0.54 grams protein = 81 grams of protein

This means you should get 68–81 grams of protein per day.

So, what does this mean in terms of real food? Because little protein comes from vegetables, you'll need to be aware of other foods from which you can obtain the protein you need. By eating regularly from the foods on the list below, you'll get more than enough. Remember, too, that combining several foods in one recipe makes it easier.

• 8 oz. milk/yogurt = 8 grams protein
• 1 cup tempeh = 31 grams
• 1/2 cup cooked or 1 cup raw vegetables = 2 grams
• 1 cup cooked beans = 16 grams
• 1/2 cup tofu = 8 grams
• 1 large egg = 7 grams
• 2 Tbs. peanut butter = 8 grams
• 1 cup low-fat ricotta/cottage cheese = 28 grams
• 1 oz. nuts = 6 grams
• 1 cup regular trail mix = 21 grams

Article by Katherine Tallmadge from Vegetarian Times, January 2005.
Copyright© Vegetarian Times. Reprinted with permission.