Protein to maintain or rebuild muscle is vital to health, but thinking only in terms of total amount now appears to be missing the boat. Gradual loss of muscle typical as we get older is not just a concern for how it slows metabolism – making it easy to gain weight and hard to lose it. Loss of lean muscle sneaks up on you, limiting your ability to take care of daily life activities. When it becomes significant, especially after an illness or prolonged bedrest, it’s linked to mortality.
Here in Part 1 of a series, Doug Paddon-Jones, PhD, explains ground-breaking research on crucial points that determine how protein is used to build and maintain muscle. Dr. Paddon-Jones is Associate Professor in the Department of Physical Therapy at the University of Texas Medical Branch in Galveston, where he conducts research on muscle loss and formation. The new understandings he shares here are completely changing ideas about how eating choices and timing support your long-term health.
Following the video, read on for clarifying details.
Total Protein vs Protein Distribution
Protein in our diet provides “essential amino acids” (ones the body can’t make from other sources) that are the building blocks of body proteins in muscle, enzymes and hormones. Although dietitians and nutrition researchers often discuss protein amount as a proportion of calories, official recommendations, called Dietary Reference Intakes, are based on body weight. These standards call for about 0.4 grams of protein per pound of body weight as an amount that meets the needs of almost all healthy adults. Certain health problems or medications may increase needs. And up to about 1 gram of protein per pound of body weight is identified as safe for healthy adults.
Research by Dr. Paddon-Jones and others, however, shows that it’s protein’s availability through the day that determines how much of the protein you eat actually gets used to create and repair muscle.
- The body can use about 30 grams of protein consumed at one time to build muscle. Anything beyond that can be used as a source of calories, but apparently does not further enhance muscle formation. Large portions of protein-rich foods don’t build any more muscle than moderate portions.
- Too little protein at one time, even though contributing to total for the day, may not do all we think. Studies suggest a “threshold” we need to get over. A meal with 10 grams of protein may not provide enough to cross that threshold and support muscle growth. A breakfast or even lunch with 10 grams of protein is not unusual among health-conscious adults, and many Americans eat most of their protein at dinner.
- Although we often hear people talk about eating five or six mini-meals daily in an effort to maintain energy or support weight loss, this research suggests problems with such an approach. Even a moderately high 90 grams of total protein for the day (which is actually typical in the U.S.), if broken down into six mini-meals with 15 grams of protein each, may never get over the threshold needed to stimulate muscle formation.
- Young people show some decrease in muscle formation with small amounts of protein at a time, but older adults are especially affected. Among healthy middle-aged and older adults, decreased muscle may not be dramatic, but would probably contribute to a gradual loss of muscle over time. In people who are ill, the impact could be significant more quickly.
A Typical Example: Why Distribution of Your Protein Matters
Dr. Paddon-Jones gives the example of someone who gets about 10 grams of protein at breakfast, 15 grams at lunch, and with a “protein extravaganza” typical of many Americans, gets 65 grams of protein at dinner. This adds up to 90 grams of protein, which for a 152-pound woman would be well within total protein recommendations, supplying about 0.6 grams of protein per pound of body weight.
10 + 15 + 65 = 90…..but effectively equals 55 or less
However, since only 30 grams of that dinner protein can be used for muscle tissue, her “usable” protein for muscle support totals about 55 grams for the day. This does meet the minimum recommendation for health. But the 10 grams of protein at breakfast, and perhaps even the 15 grams at lunch, may not have been enough to support muscle formation, bringing the “effective” total even lower. What’s more, emerging research suggests that current total recommendations may not be enough to meet needs of older adults.
Bonus for a healthy weight: protein in our diet supports satiety – keeping you from the hunger that can derail your calorie-cutting attempts to lose weight. Protein in the range that supports muscle also supports satiety. Very high amounts that aren’t any better for muscle, also show no added benefit for satiety.
Before you forget, sign up by RSS feed or email to make sure you don’t miss the next Smart Bytes®! — You won’t want to miss the next segments of my interview with Dr. Paddon-Jones, when we talk about how choices of protein-containing foods play into this issue, and what it means for people with special protein needs.
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Symons TB, Sheffield-Moore M, Wolfe RR, Paddon-Jones D. A moderate serving of high-quality protein maximally stimulates skeletal muscle protein synthesis in young and elderly subjects. J Am Diet Assoc. 2009 Sep;109(9):1582-6.
Paddon-Jones D, Short KR, Campbell WW, Volpi E, Wolfe RR. Role of dietary protein in the sarcopenia of aging. Am J Clin Nutr. 2008 May;87(5):1562S-1566S.
Leidy HJ, Tang M, Armstrong CL, Martin CB, Campbell WW. The effects of consuming frequent, higher protein meals on appetite and satiety during weight loss in overweight/obese men. Obesity (Silver Spring). 2011 Apr;19(4):818-24.