Both men and women lose muscle mass with age. Muscle mass begins to decline after the age of 30. Men and women who are inactive lose as much as 3 to 5% of their muscle mass each decade after the big 30. Loss of muscle mass isn’t just a cosmetic problem. When you lose muscle tissue and strength, you’re at greater risk for falls, injuries, and accidents. That’s why sarcopenia, the age-related loss of muscle, is now recognized as a major health issue.
Although men and women both lose muscle mass with age, women may have an easier time avoiding sarcopenia than men once they reach a certain age. Some studies reveal women lose lean body mass more slowly than men later in life. For example, a study in the 1970s showed between the ages of 25 and 65, the average woman loses about 11 pounds of muscle while the average male loses more than twice as much. Of course, these are men and women who haven’t resistance trained to help preserve the muscle they have. The question is why do men naturally lose more muscle mass than women as they grow older?
Men and Women Respond Differently to a Protein Meal
A study published in PLOS One looked at the issue of gender and loss of muscle due to aging. Researchers used muscle biopsies, protein drinks and intravenous infusions of amino acids to see how men and women age 65 and over responded to protein intake. Each participant was asked to drink a protein drink after undergoing a muscle biopsy. The muscle biopsy was repeated after each participant had finished their drink.
Based on the muscle biopsies, male participants showed a greater increase in muscle protein synthesis after drinking the protein drink than women BUT the women had greater baseline muscle protein synthesis throughout the day relative to men. In other words, older men get a greater boost in muscle protein synthesis in response to a protein meal but synthesize less when they haven’t eaten protein. Women synthesize more muscle protein than men throughout the day, yet don’t as easily jumpstart muscle protein synthesis in response to a meal. All in all, women have the advantage when it comes to preserving lean body mass because they spend more TOTAL time making muscle protein than men.
The picture isn’t as rosy as it sounds for women. Women have less lean body mass than men to begin with. As a result, they can’t afford to lose a lot. That’s why strength training and getting enough dietary protein is so essential. One thing this study points out is older women get less muscle protein synthesis in response to what they eat. The results of this study show older women may need to consume more protein as they get older to make up for greater difficulty in assimilating dietary protein into muscle tissue. Older women may also need to consume more protein throughout the day.
Maintaining Muscle: The Problem of Anabolic Resistance
Research suggests muscles become less responsive to anabolic stimuli, including dietary protein and resistance training, with age. This phenomenon is called anabolic resistance. As a result, women need to consume more protein and train using heavy resistance to maximally preserve lean body mass after the age of 65. Unfortunately, some women still subscribe to the myth that lifting heavy weights will make them bulky, but maximizing muscle mass becomes even more essential as the years go by.
Muscle tissue is constantly being broken down and re-synthesized. When more net muscle tissue is made than broken down, muscle mass increases. When more muscle tissue is broken down than synthesized, muscle tissue is lost. To maintain muscle tissue, you need roughly equal amounts of synthesis and breakdown. According to research, muscle protein breakdown doesn’t typically increase with age.
Most studies suggest muscle loss with aging is related to problems synthesizing muscle proteins. Why might this be? Older people may have more problems breaking digesting and absorbing dietary amino acids. Insulin resistance and hormonal issues may also be a factor. Studies also show a lack of physical activity contributes to anabolic resistance.
Interestingly, a study showed being physically active prior to eating a protein meal improved muscle protein synthesis. This isn’t surprising since exercise improves insulin sensitivity and uptake of amino acids into muscle cells.
Maintaining Muscle: What Does This Mean?
Maintaining muscle mass is vital for healthy aging. The main reason women (and men) become less functional and prone towards injury is they lose power and strength. Maintaining a healthy amount of muscle tissue requires enough protein and resistance training using adequate resistance to promote muscle growth. Anabolic resistance becomes a problem for women once they reach their 60s. Therefore, most women need to consume protein regularly throughout the day and have a protein snack within 30 minutes of completing a resistance training workout. Thirty minutes to an hour after a workout is when anabolic resistance is least. Whey protein is the most rapidly absorbed and may offer benefits over soy and casein, especially for older women with anabolic resistance.
Don’t underestimate the importance of diet for muscle growth. Make sure you’re getting enough protein AND progressively challenging your muscles when you work out.
WebMD. “Sarcopenia With Aging”
PLOS One. “Differences in Muscle Protein Synthesis and Anabolic Signaling in the Postabsorptive State and in Response to Food in 65-80 Year Old Men and Women” (2008)
Metabolism – Clinical and Experimental
Volume 19, Issue 9, Pages 653-663, September 1970.
Nutrition & Metabolism 2011, 8:68 doi:10.1186/1743-7075-8-68.
Am. J. Clin. Nutr. 2011; 93:322-31.
Medscape.com. “Anabolic Resistance of Muscle Protein Synthesis With Aging”
PLOS One. “ER Stress Induces Anabolic Resistance in Muscle Cells through PKB-Induced Blockade of mTORC1”
Gatorade Sports Science. “Protein Consumption and Resistance Exercise: Maximizing Anabolic Potential”
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