Does your metabolism slow down after 40?

Short answer

Not the way most people think. A large 2021 study found that average daily energy expenditure, adjusted for fat-free mass and fat mass, was stable from about ages 20 to 60. Individual calorie needs can still change with body composition and activity, and sleep and menopause may also contribute to midlife weight changes.

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By Coach Josh · Get Your BMR

3 sources · Reviewed October 29, 2026

The short version

  • Adjusted energy expenditure was stable from about 20 to 60
  • Body composition and activity still matter
  • No supplement “resets” your metabolism
Illustration: a confident woman in her forties with grey-streaked hair walking under autumn trees.

What the 2021 study found

Researchers led by Herman Pontzer pooled a large database of daily energy use, measured with doubly labeled water, in people aged 8 days to 95 years. After accounting for body size and fat-free mass, energy use stayed stable through adulthood, from about 20 to 60, even during pregnancy. It started to decline after 60.

So the study does not support a sudden, age-driven “metabolism crash” at 40.

Then why is it harder after 40?

Real things change in midlife, just not a switch in your metabolism. Many women lose some muscle, move less as life gets busier, sleep less, and go through perimenopause and menopause, which The Menopause Society links with changes in where the body stores fat. These are possible contributors, and together they can make a real difference.

Can you boost your metabolism?

These sources do not establish a supplement or food that “resets” metabolism. Keeping muscle with strength work, and adding walking, are the parts you control.

Start with your numbers

Your calorie needs depend on your size and activity today, not your age alone. The free Get Your BMR quiz estimates your BMR and a daily target, and never cuts a woman below 1,200 calories.

Find your number first

Your BMR estimate, a daily calorie target & Coach Josh’s protein range, from four quick questions.

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The 3-Day Walk & Water Challenge

How a round works

  1. 1. Join a team

    Two to four of you on one team: a friend’s, your own, or one you join in the app. Your team gets a name, a crest & a spot on the live leaderboard.

  2. 2. Walk + water, 3 days

    Tuesday, Wednesday & Thursday. A step goal & a water goal sized to where you are today. The board updates as you walk & closes Thursday at midnight, Arizona time.

  3. 3. Friday winners

    Friday morning the results go up. The winning team’s card glows gold, badges land beside names on the board, and a new round starts Tuesday.

Bigger isn’t better. Teams rank on their AVERAGE.

A team’s score is its average per woman, not its total. So two friends can beat a team of four, and every walker’s day counts the same. When one of you goes quiet, the others notice & send a nudge in team chat.

The Walk & Water team card: team name and crest, team level, the average steps per woman, and each teammate’s steps and glasses of water.
Your team card. The big number is the average per woman.
The Walk & Water leaderboard: your rank this week, steps, glasses of water, day streak, and the 3-day challenge rankings.
The live leaderboard. Solo, team & global ranks for this round.

What actually helps

No supplements or tricks. Three habits that change what you burn and what you eat.

  1. Keep your muscle

    Strength work on 2 or more days a week, as U.S. guidelines advise. Strength work helps maintain muscle.

  2. Move more on most days

    Walking is the easiest place to start. More steps add to what you burn.

  3. Know your number

    Recheck your calorie estimate when your weight or routine changes.

Questions

Does metabolism slow down after 40?

A large 2021 study found that average daily energy expenditure, adjusted for fat-free mass and fat mass, was stable from about ages 20 to 60. Individual calorie needs can still change with body composition and activity.

How can I boost my metabolism after 40?

Strength work on 2 or more days a week helps maintain muscle, and moving more adds to what you burn. These sources do not establish a supplement or food that resets metabolism.

Why am I gaining weight in my 40s?

Common contributors include losing muscle, moving less, poor sleep, some medicines and menopause. See your doctor if the gain is fast or unexplained.

Does menopause slow metabolism?

The 2021 study found that average daily energy expenditure, adjusted for fat-free mass and fat mass, was stable from about ages 20 to 60. Individual calorie needs can still change with body composition and activity. Menopause is linked with changes in body composition and where fat is stored.

Sources

Written by Coach Josh and checked against these sources on October 29, 2026. General information, not medical advice.

Show all 3 sources
  1. Pontzer et al. (2021). Daily energy expenditure through the human life course. Science
  2. The Menopause Society — MenoNote: Midlife Weight Gain
  3. U.S. Department of Health and Human Services — Physical Activity Guidelines for Americans, 2nd edition
Coach Josh

Who writes these guides

Coach Josh

Professional trainer since 2018 · ISSA & NCCPT certified · Creator of Get Your BMR & the Walk & Water Challenge (BodyByReason)

I’m Josh. I built Get Your BMR so you could see what your body burns at rest, & I built Walk & Water so you’d have somewhere to use it with people who notice when you show up.

I walk every round too: same board, same three days, on my own team. I don’t always win. Tap Chat with Coach in the app & it’s me who answers.

About 7 in 10 women who finish a round come back & play the next one.

Walk & Water app data, 73 finishers, snapshot October 19, 2026.

Start with your number

Get my BMR estimate

Free · 4 questions · no email needed to see it

Already know your number? Join the 3-Day Walk & Water Challenge

Related guides

Get Your BMR is Coach Josh’s free calculator. The 3-Day Walk & Water Challenge is where you put the number to work, and it runs inside the APEX: Walk & Water app on iPhone and Android.