Does Your Metabolism Slow as You Age?

It’s considered an inevitable part of life that as you age, you’ll gain weight more easily and have even more trouble losing it.

It’s a lie.

Things do change as you get older — don’t get me wrong. There are certain differences you have to account for, and your metabolism plays a role in that.

But after coaching many people in their 30’s, 40’s, 50’s, and beyond, I’ve seen firsthand that for anyone at any age:

✅Losing weight doesn’t have to be a giant guessing game.

✅ Gaining weight isn’t an unavoidable part of getting older.

✅ You can have MORE control over your body than ever before.

As for your metabolism… it may change, it may not. The real question is, what should you do about it?

My Age and Metabolism

The first time I ever paid attention to my diet and tracked everything I ate, I was in my upper 20’s.

I wasn’t very good at it (as is the case with everyone when they first start out), but I can give you a rough estimate of how many calories I could eat each day without losing or gaining weight:


That’s a lot (even for my size).

Compare that to now, at 37 years old, and I’m currently maintaining my weight at roughly 2,750 calories.

I’m sure you’re good enough at math to realize that’s a difference of 750 calories between now and 10 years ago.

If I were just going about my life, continuing to eat the same amount as I used to, I’d gain more than a pound every week!

I’m clearly not a special case with super-human genetics. At first glance, it would make total sense for me to assume that my metabolism slowed down with age.

But there’s more to it than that.

Real Life Evidence

“If the internet says it, it has to be true” is a common joke.

I mention this because I know it can be difficult to trust some random study referenced on the interwebs.

But there was a research paper published recently that answered the question of whether your metabolism slows as you age, and it’s not just something I cherry-picked out of convenience.

It’s a massive study that was done by an astounding 83 authors (if I counted correctly), including the lead author who was already an established researcher in this field of study.

It involved over 6,000 people (2/3rds women), ages 8 days old (yep, days!) to 95 years old, in 29 different countries.

It’s legit (here’s the link).

The results of the study showed pretty conclusively that, between the ages of 20 and 60, your age doesn’t directly affect your metabolism. (And even after 60, the changes are less significant than you might think.)

But even though the equation is NOT:

You + Another Birthday = Slower Metabolism

…there’s a reason your metabolism may slow down anyway. There’s also another reason why it may only SEEM to slow down.

In either case, it’s avoidable if you make the right moves.

Let’s look at both.

1. Your Activity Level

As we get older, oftentimes it’s not that our metabolism slows down… it’s that WE do.

In other words, there’s a good chance you burn less calories now per day than you used to, but not because something changed internally. Rather, it’s because your external day-to-day activities are different than they used to be.

In my case, I know that’s what happened.

Ten years ago I had a job where I was on my feet most of the day. Now, as an online fitness and nutrition coach, I spend a lot of time on a computer sitting at my desk.

Don’t get me wrong, I’m not sedentary.

I work out 3 times per week.

I go for regular walks.

I rarely spend my limited free time in front of the TV.

I’m still active, just not as much as I was 10 years ago. And it’s reflected by the fact that I’m now eating 750 less calories than I used to so I don’t gain weight.

What to Do About It

With all other things being equal, if you’re as active at age 40 as at age 20, you could eat the same way and experience the same results (positive or negative).

You aren’t at a disadvantage just because you’re older by two decades. It only feels that way because you’ve gotten busier with “adulting.”

Because of that, it’s not realistic to think you can all of a sudden start living life like you did when you were young, single, and childless.

But what CAN you do? Could you:

⏰ Manage a workout 3 times per week for 30 minutes?

⚾️ Join a friend’s recreational softball team?

🚶‍♀️ Go for a short walk when the weather is half-decent?

⌚️ Have a realistic step count goal?

Any of those things will help.

You might not get to where you can eat like you did when you were 20.


On the other hand, if you’ve been inactive most of your life, you could get to where you can eat MORE than you did back then and even lose weight while doing it.

2. Your Lean Mass

OK, so your activity level affects how many calories you burn. But what if you’re fairly confident your activity level hasn’t changed over the years and you still have more trouble losing weight now?

What if your metabolism actually HAS slowed down?

It’s possible.

There are a number of different circumstances that can play a role in slowing your metabolism, but every single one of them boils down to a loss of lean mass (simplistically, this means muscle loss) — not age.

And while some of the things that contribute to muscle loss are often a byproduct of getting older…

  • Being less active (aka “adulting”)

  • Higher stress from work

  • Lack of sleep from kids

  • Obesity (more common in adults)

  • Menopausal hormone changes

…the negative effects to your metabolism can largely be avoided.

In fact, they can be avoided to the point where you hardly notice it at all.

What to Do About It

This is where the advice to simply “be more active” falls short.

As we’ve already seen, being active can help overall. But no matter how active you are, it isn’t addressing the specific problem of a slowed metabolism.

Since that comes from muscle loss and not simply the number of years you’ve been alive, there’s really only one solution:

Strength training.

And here’s where age DOES come into play.

A 40 year old mother of 3 should not be trying to follow the exercise program of a 20 year old collegiate athlete.

You may need more recovery time between workouts. You may have more past injuries that affect how you feel when you exercise.

You probably just have less time.

You can still reach your goals. You can still have a thriving metabolism and lose weight. You can be as strong, confident, and full of energy as you’ve ever been and more!

You just need workouts that fit your life as it is now (read 7 Key Strategies on Exercising for Weight Loss), not some arbitrary “ideal” you wish you could achieve.

And that’s ok — it’s not “slacking off,” it’s being smart.

In fact, more 22 year olds would do better to already start exercising like they’re 40 so they can have a more realistic foundation for staying fit as THEY get older.