There's an exception. Feeding boosts muscle protein synthesis in men but not in women, note the researchers, who included Bettina Mittendorfer, PhD, of Washington University in St. Louis.
But most of the day isn't spent eating. So Mittendorfer's team argues that their findings may "partially explain the slower loss of muscle in older women."
"However," Mittendorfer tells WebMD via email, "one thing to consider is that women start out with less muscle mass so that overall they are probably at greater risk to reach a threshold of muscle loss that leads to functional disabilities. Their lack of response to food [in terms of making muscle protein] is a big problem for the prevention of age-associated loss of muscle mass."
The researchers studied 13 men and 16 women aged 65-80. Participants got muscle biopsies before and after drinking a liquid meal replacement.
Here's a key point that put all of their muscles at risk: None of the participants got regular exercise. Man or woman, young or old, that doesn't bode well for muscle strength.
Muscle loss picks up its pace with age. Exercise, especially strength training, builds muscle. It's never too late to start, but do check with your doctor first.
"Exercise [both strength and endurance] is obviously very important for preserving muscle mass and function as good as possible," writes Mittendorfer. "So far we only have preliminary data for this, but it looks like as with eating, old women do not gain as much muscle from working out as men do. Thus, it is particularly important for women to engage in exercise and eat well and enough protein ... to help keep their muscles."
The study appears in Public Library of Science One.