The Protein Puzzle

photo by ADA

The Washington Post
By Katherine Tallmadge

When I work with clients who are interested in losing weight I urge them to avoid falling into an easy, tempting but very unhealthy trap: making draconian cuts in their consumption of protein. Not all of us are on low-carb, high-protein diets. We love our soup and salad at lunch, and adding protein can mean adding calories.

Protein is essential for healthy living. It is one of the most important nutrients in the human body.

“Bone health, muscle function, muscle strength, muscle mass and immune function — all are impaired with a low protein intake,” says Carmen Castaneda, protein researcher and acting director of the Nutrition, Exercise Physiology and Sarcopenia Laboratory at the Human Nutrition Research Center on Aging at Tufts University.

But how much protein do we need, dieting or not?

I first became interested in this issue when I came across a study that found that people who ate the recommended dietary allowance of protein experienced alarming bone losses as compared with those who ate higher protein levels. This grabbed my attention. The recommended dietary allowance (RDA) is a guideline for healthful eating that is set by the Food and Nutrition Board of the National Research Council of the National Academy of Science. The amount of protein it recommends depends on several factors, such as sex and age. But if the study found that people who were eating the recommended amount of protein were still losing bone mass, what could it mean for those of us who weren’t eating even the minimum requirement? Or for those of us who were trying to lose weight by cutting back on protein?

New research has found that a higher protein diet is essential to effective weight loss: it’s more likely to minimize muscle loss and maximize fat loss. Keeping muscle stores high is critical for several reasons.

“Losing muscle decreases resting metabolic rate, making it harder to maintain a healthy weight and lose body 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.

Protein is also essential for bone health. Should we risk bone loss tomorrow to lose pounds today?

Your bones, composed of protein, calcium and other minerals, are constantly in a state of flux and in need of replenishment to keep them strong and dense. Until age 30, you are building bone mass. After your early thirties, you’re losing it. It’s critical to maximize your bone mass, so that your bones are strong and dense enough to prevent osteoporosis. Osteoporosis leads to humped backs, broken bones and pain for its 10 million sufferers in the United States.

For many years, scientists have observed that protein undernutrition was associated with osteoporosis, frailty and bone fractures. But the relationship had never been fully understood until researchers decided to test the theory for the first time in a group of 855 participants from the Framingham Study (originally established in 1948). Researchers analyzed food intake and bone mass every other year for four years. Their findings, published in the Journal of Bone and Mineral Research in 2000, were dramatic.

The subjects eating the lowest protein diets lost the most bone mass — 4 percent in four years. People who ate the highest protein diets experienced the smallest losses — less than 1.5 percent in four years. Think about it: If you’re losing as much as 4 percent of your bone mass in four years, that means that one-fifth of your bone mass will be lost in 20 years. That is not a positive development.

And while these studies were conducted on older men and women (68-plus years old), Katherine Tucker, Associate Professor of Nutritional Epidemiology at Tufts University, says the data may be important to people of all ages.

“At younger ages, you need the protein to build the bone, and after age 30 you need the protein to protect the bone from being lost,” said Tucker. “Keeping bones is a life-long effort,” she said.

This study and others have shown that eating about 20 percent of your calories as protein protected bone mass most efficiently — but that’s more than the recommended dietary allowance (RDA) for protein, which is about 15 percent of calories.

Should the requirement be changed?

It’s been reported for years that high-protein diets result in high levels of calcium in the urine, and it’s been assumed that this would affect bone mass negatively and might produce kidney stones. But it appears, instead, to be a function of just how much protein is consumed and how balanced the diet is. The National Academy of Sciences, in a recent report, recommended Americans never exceed 35 percent of their calories as protein, as that may be when adverse symptoms begin to appear. Other researchers surmise that if protein is extremely high while carbohydrates are very low, this may be responsible for the negative consequences.

It may take years before this new research is confirmed by additional studies and in turn can result in changes in the offcial recommended protein levels.

In the meantime, it would not be harmful to increase protein intakes to 20 percent of calories, says NAS food and nutrition board protein panelist Peter Garlick.

“Even though the National Academy of Science’s Food and Nutrition board did not change the RDA for protein because we’re still waiting for more evidence to show that it’s necessary, these are safe and reasonable levels,” said Garlick.

In Pursuit of Protein

Although for most Americans the recommended dietary allowance of protein may be adequate, if you’re losing weight or are worried about bone loss, consider increasing your protein.

Protein can be found in a wide range of foods. Animal protein is in seafood, dairy, meat, poultry and eggs. Vegetarian protein can be found in legumes, soy, vegetables and grains. And while it’s true that high-protein foods often bring fat and calories along as uninvited guests, it doesn’t have to be that way.

The lowest-calorie animal protein sources are the leanest. Go for seafood, poultry with no skin, lean veal cuts, pork tenderloin, lean beef cuts such as the round or tenderloin or 95 percent lean hams (less than 3 grams of fat per ounce). Soy products also provide great low-calorie options.

Toss four ounces of lean beef, chicken or seafood or 12 ounces of spiced tofu into your salad and gain 28 grams of high-quality protein and no more than 150 to 200 calories.


At present, the recommended dietary allowance for protein is computed using the following formula:

0.37 grams of protein per pound of body (this usually means people are eating about 15 percent of their calories as protein).

But some evidence suggests that to protect bones and muscle we can consume more, though the amount of protein should never be more than 35 percent of daily calories.

So, if you weigh 150 pounds, this means the minimum amount is:

150 pounds X 0.37 grams protein per pound = 55.5 grams of protein

But you could safely increase your protein intake:

150 pounds X 0.45 grams protein per pound = 67.5 grams of protein

150 pounds X 0.55 grams protein per pound = 82.5 grams of protein

So, the sample 150-pound active woman should get between 67.5 and 82.5 grams of protein per day


8 ounces milk/yogurt . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 grams protein

1/2 cup cooked beans/tofu . . . . . . . . . . . . . . . . . . . . . . . . 8 grams protein

1 ounce meat/fish/chicken/cheese (the leaner the meat,

the more protein and the fewer calories). . . . . . . . . . . 7 grams protein

1 large egg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 grams protein

1/2 cup cooked or one ounce dry

(1 slice bread) grain . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 grams protein

1/2 cup cooked or one cup raw vegetables . . . . . . . . . . . . 2 grams protein

— Katherine Tallmadge

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