Fighting 40s Flab

It ranks right up there with "the check is in the mail," "the dog ate my homework," and "I will never lie to the American people." Of course, we're talking about "It isn't me, it's my metabolism."

Well, if you're over age 40, the oldest cop-out in the book may have some truth to it after all. Yes Virginia, you really can blame it on your metabolism.

But only a little.

Even if you're sitting or lying down while reading this article, your body is still burning calories; the rate at which it does so is called your resting metabolic rate. As you age, your metabolism tends to decelerate by about 5% for every decade of life past age 40, so that if your resting metabolic rate is, say, 1,200 calories per day at age 40, it will be around 1,140 at age 50.

"At age 40 to maintain your weight, that is to not gain weight, you're going to have to eat 100 calories less a day, and that has nothing to do with anything other than the natural course of aging. That means your resting metabolic rate," Madelyn Fernstrom, PhD, director of the University of Pittsburgh Medical Center Weight Management Center and associate director of the UPMC Nutrition Center in Pittsburgh, tells WebMD.

But metabolism is really only a small part of the story. Age and life tend to conspire against us in the battle to lose weight over 40, Fernstrom says.

"As we age, our lives become more complicated, whether it's with children, with work, with aging parents, and so we have less time really to be more physically active and pay attention to what we're eating. Food is available 24 hours a day, seven days a week, in large portions that are relatively economical and so food is always around, and we tend to have more mindless eating and cut down on activities," she says.

Mass Exodus

When it comes to pinning blame on changes in metabolism there are handful of prime suspects, says Pamela Peeke, MD, assistant clinical professor of medicine at the University of Maryland School of Medicine in Baltimore, who specializes in nutrition and stress, particularly among adults on the far side of 40.

"Metabolism is based upon three different factors," Peeke tells WebMD. "The first factor is genetics. We're good, but we can't fudge with that yet -- give us time, however.

"Number two is thyroid function, and interestingly enough, here's where we get gender specificity. Women have much greater thyroid issues than men, by a at least 10 to 1, and it's quite gradual, so women may find that they're losing some of that metabolic edge during their 40s also because thyroid issues begin to spring up."