Optimum protein levels

Vicki Koenig, MS, RD, CDN

How much protein do we need? We need a minimum for growth and maintenance. Some studies suggest there are benefits to increasing protein intake beyond this. What’s optimum?

Minimum protein needs

The recommended daily allowance (RDA) for protein means adequate to meet the known nutrient needs for practically all healthy people. The minimum adult RDA is considered 0.8 grams per kilogram of body weight. To calculate your needs, divide your weight in pounds by 2.2 (2.2 lbs =
1 kg).

A 150-lb. person needs at least 54 grams of protein per day
(150 ÷ 2.2) = 68 kg × 0.8 = 54 grams

Most Americans get enough protein. Half our protein comes from concentrated sources like meat, chicken, fish, cheese, milk, yogurt, legumes, nuts, seeds and eggs. The other half is from vegetables and grains. Here’s a description of common protein-rich foods.

Average protein grams per serving

What’s optimum for specific needs?

• Weight loss. A 2009 study found that moderate protein at 1.6 grams per kg sustained weight loss greater than the carbohydrate diet at 12 months. Those on the protein diet lost more fat and maintained more lean tissue. The study compared 125 grams to 65 grams of protein per day. Unlike very high-protein diets, these diets still contain significant amounts of fiber.
• Exercise. Higher levels of protein can build muscle for athletes. There is no exact formula for all sports; the timing of protein as well as type of amino acids may be more important. Studies suggest athletes are more efficient at using protein for muscle building versus breaking it down for energy. Eating more than the RDA may help with training.
• Diabetes and blood sugar control. A 2003 study showed that a diet with 1.6 grams of protein per kg of body weight stabilized glucose levels with less insulin during weight loss, compared with a high-carbohydrate diet.
• Strong bones. Bone requires protein to be synthesized along with calcium. If calcium intake is low and protein is high, calcium will be excreted. Dairy is considered a well-absorbed form. Perhaps this is because it has both calcium and protein.

Too much protein?

There is limited evidence for harmful effects from a high-protein diet. Our bodies use it or modify it for energy. Check with your doctor before making changes in your diet. Choose healthy carbs and a moderate amount of lean protein, and don’t forget the fiber. Include low-fat dairy products such as milk and yogurt, and you’re covering your bases and your bones.

For more information:

• Farnsworth E et al. “Effect of a high-protein, energy-restricted diet on body composition, glycemic control, and lipid concentrations in overweight and obese hyperinsulinemic men and women.” Am J Clin Nutr Jul 2003;78(1):31–39.
• Food and Nutrition Board. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. 2005. 1324–25.
• Layman DK. “Protein Quantity and Quality at Levels above the RDA Improves Adult Weight Loss.” J Am Coll Nutr 2004;23(90006):631S–636S.
• Layman DK and Baum JI. "Dietary Protein Impact on Glycemic Control during Weight Loss.” J Nutr Apr 2004;134:968S–973S.
• Layman DK et al. “A Moderate-Protein Diet Produces Sustained Weight Loss and Long-Term Changes in Body Composition and Blood Lipids in Obese Adults.” J Nutr Mar 2009;139(3):514–521.
• Noakes M et al. “Effect of an energy-restricted, high-protein, low-fat diet relative to a conventional high-carbohydrate, low-fat diet on weight loss, body composition, nutritional status, and markers of cardiovascular health in obese women.” Am J Clin Nutr Jun 2005;81(6):1298–1306.
• Roughead ZK. “Is the Interaction between Dietary Protein and Calcium Destructive or Constructive for Bone?: Summary.” J Nutr Mar 2003; 133(3):866S–869S.