You remember the moment it hit you: When you realize that, even though you’ve been eating about the same and exercising a fair amount, you’ve put on a few pounds.
Or, you came back from vacation only to realize you weren’t bouncing back as quickly as you used to from the fried foods and frozen margaritas (#noregrets). Maybe you’re not entirely sure what’s going on, but you think you have an idea: Your metabolism is slowing down.
And you are probably correct.
Caroline Cederquist, M.D., author of The MD Factor Diet, says that while it’s different for everybody, your metabolism slows down as you age. For most, it starts in your 20s or 30s. For others, it may not happen until your 40s or 50s. Regardless, it’s important to know how your metabolic system works, so you can keep its engines running at full throttle.
In Your 20s
On average, this is when most people experience their highest resting metabolic rate (RMR) — aka when your body burns the most calories just by sitting still. “Some of it is based on genetics, but a large part of it has to do with how active you are,” says Cederquist. We tend to have fewer commitments, which frees up time for active movement.
Not to mention your body continuously builds bone until you’re about 25, a process which gives your calorie burn a boost. In your late twenties you might start to notice that you can’t eat quite as frivolously as you used to, but for the most part, your body can bounce back quickly with a cleaner diet and regular exercise.
In Your 30s
If you haven’t started strength training yet, Caroline Apovian, M.D., author of The Age-Defying Diet: Outsmart Your Metabolism to Lose Weight, says now’s the time. “Your resting metabolic rate is directly related to your muscle mass,” she says. “The more you have, the more energy you’ll burn even when you’re not working out.”
The problem is that when you hit your 30s your muscle mass starts to naturally decline, says Apovian. “You lose about one percent each year,” she explains. But it doesn’t have to be that way. “When you don’t use your muscles, you’re essentially telling your body that you don’t need it, so it starts to store more fat,” she says. To prevent that, add strength training to your schedule two to three times a week.
Women may want to lean toward the higher end of that spectrum, as it takes more effort for them to maintain muscle mass, says Cederquist. Men typically have more testosterone, which contributes to a lower body fat percentage and more muscle tissue, both of which rev your metabolic engine.
As if that wasn’t enough, your 30s are also the decade in which you produce less human growth hormone (HGH), leading to a dip in metabolism, says Cederquist. Once again, though, strength training can help you produce more of it — so hit the weights already!
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