Muscle Mass and Aging

At 67 and looking preternaturally younger, Westcott has the same body composition as when he was in his 20s: He’s only about 12 percent fat, compared to an average American man’s 28 percent.

But the key isn’t fat, it’s muscle: His central point is that loss of muscle mass -- whether through inactivity or aging or dieting -- helps lead to many of our ills, from regaining weight to developing diabetes.

But it doesn’t have to be that way, if only we’ll do a modicum of strength training — defined as any exercise that uses resistance to build muscle, from weightlifting to push-ups --  and keep doing it.


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Twice a week of effective strength training is enough to maintain bone and muscle mass, according to the body of data that Westcott has helped build. In published studies of nearly 3,000 people, he said, twice a week is just as good as three days a week for muscle health.

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“If someone says, ‘I lost four pounds this week!’ Well, your body can only metabolize, or energize, about two pounds of fat per week maximum, so the other two pounds have to come from some other tissue,” he said. “And people say, ‘Well, it’s just water weight!’ And that’s partly true -- it is water, because water is stored in muscle. Muscle is about 77 percent water. Fat is only 7 percent water.

“So when you’re losing water weight, that’s not a good thing. That’s not coming from fat. That means you’re losing water from your muscles, and also the muscle proteins. So if a person loses four pounds a week, they may have lost two pounds of fat but almost two pounds of lean tissue, most of which would be muscle.”

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So muscle loss helps slow metabolism, and then the news gets even worse: “When you gain the weight back -- and 95 percent of people who are successful dieters regain all the weight they’ve lost, typically within one year -- you gain back more fat and less muscle than you lost.

“So when you return to the same weight, you say, ‘At least I’m no worse off than I was before,’ but yes, you are. You have more fat, less muscle. Your metabolism is lower, so you have to eat less. You’re going to gain weight again.”

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Van Joolen hit his peak weight of 237 after a cruise in December; he now weighs 190, and can do pull-ups and dips as part of his workouts. Before he enrolled in Westcott’s study, he said, there were parts of his body he thought would never go away -- mainly the fat around his middle.

“The first thing I noticed was, the love handles went away,” van Joolen said. “I was kind of shocked.”

Westcott celebrates van Joolen’s achievement with him but also cautioned, “He lost 45 pounds in six months, and one third of that loss was muscle. You can’t lose that much weight that quickly.”

Van Joolen is gaining the muscle back, Westcott added encouragingly, but often such muscle loss leads to a metabolic slowdown, which leads to a weight plateau, which frustrates people so much they give up.

“If you diet without strength training, you have to eat less and less,” he said. “If you diet with strength training, even when you hit your goal weight you can eat more, because you have more muscle mass and most likely a higher resting energy expenditure.”

Obesity specialists also emphasize that less extreme weight loss -- just 5 or 10 percent of a person’s weight -- tends to be more sustainable.

Source: WBUR