Metabolism and Weight System

You've probably been told it's your metabolism, that the body just burns less fat as the years go by, and the change around your weight is the price of getting older. It's a believable story, and an easy one to take for granted. However, it's not as we think it is. A research done in 2021 measured the energy the body burns, across thousands of people from babies to the elderly, it was consistent from our twenties through our fifties, and didn't really begin to drop until around sixty years old.¹

So if it's not your metabolism, what is it? It's the balance between fat and muscle that's shifting. Around this time, your body starts storing fat about twice as fast as before, and losing muscle at the same time.² That's why your clothes can fit differently, even though you haven't changed a thing about how you eat or move.

It's easy to take that very personal, like you've slipped, but you haven't. This is a hormonal shift with its own science, and the rest of this guide walks you through it: where the fat goes to, why muscle is the thing to protect, why food can taste and feel different, and what helps the most.

Why Your Shape Changes More Than the Scale Shows

Here's the part that throws everyone off: your body composition can shift faster than what any scale can show. On the inside, you're losing muscle and gaining more fat. Your body is always breaking muscle down and rebuilding it, and estrogen helps the rebuild. As it falls, you rebuild muscle slower than the muscle that is being broken down, so muscle mass starts going down.³ Some of that is due to age, but perimenopause speeds it up.

The extra weight is more of a secondary effect. Muscle burns energy just by being there throughout your daily routine, if you have less muscle you burn less energy, which means more of it gets stored as fat in your body. This does not end there, estrogen also helps your body move fat just under your skin and below the waist, As estrogen drops, more of it moves to your belly, and deeper, settling in around your organs as what's called visceral fat.⁴

So what about the scale? Why doesn't it move? Fat gain speeds up at this stage, but you're losing muscle at the same time, and on the scale, the two mostly balance each other out.² So the scale barely reacts to a real change in what your body's made of.

Why Food Itself Feels Different

A lot of women notice food feels different during this transition. There are two things that change, and both are real, not in your head.

The first is hunger. Estrogen helps your brain feel full, working on the switch that tells you you've had enough, though so far that's mostly been shown in animal studies and more research is needed.⁵ As estrogen drops, that sensation seems to fade, and the same meal that used to fill you up can leave you wanting more. That's not weak willpower; you just don't feel as full as you used to.

The second is taste, and this one surprises people. In smaller studies, women past menopause have a harder time picking up sweetness, they need to eat more of it to taste the same thing.⁶ Because of this, it's easy to reach for more food to get the same hit. The difference now is where that extra sugar goes.

Why Blood Sugar Gets Harder to Manage

Estrogen helps your body handle blood sugar as well, and here's how. After you eat, insulin tells your cells, mostly your muscles, to pull sugar out of your blood and burn it for energy. Estrogen helps your muscles hear that signal and take the sugar in.⁷ So when estrogen levels drop, they hear the signal less clearly. The sugar gets pulled in more slowly and lingers in your blood, where it should not be. And that's down to the change itself.

Two things make it worse. That visceral fat isn't just for show; it makes your muscles even slower to take sugar in. And those cravings for something sweet come up again, right when your body can't handle it.

All of this traces back to estrogen levels, and hormone therapy can bring some of that balance back for some women, so it's worth asking your doctor about it.⁷ It is recommended to keep track of your blood sugar as this transition is going on.

What May Help

This not only covers eating less, there are a few things that can be done during this transition. They're about supporting your muscles and keeping a steady blood sugar level. Some examples are:

Strength Training: This is the big one, because this transition takes your muscle, and lifting builds it back.⁸ Weights, bands, or even your own body weight all work, and the muscle you keep helps your shape and your blood sugar.
Protein: Muscles are made of protein, so you need enough to back up training, just don't overdo it. In one trial of postmenopausal women doing strength work, eating more than the recommended amount didn't build any extra muscle.⁹
Sleep: A short or restless night pushes your appetite up and messes with your blood sugar the next day, so protecting your sleep does real work here. How to do that is its own topic, and the Sleep and Thermoregulation guide covers it.
Your Gut: Your gut bacteria have a hand in how well your body handles sugar, and one in particular, Akkermansia muciniphila, keeps coming up in the research. In a small human study, the people who took it had better insulin sensitivity after three months,¹⁰ the blood-sugar side of all this. It's still new though and needs more research, but it shows the potential of this bacteria.

How This Changes From Perimenopause to Postmenopause

Here's the reassuring part: The fastest changes appear in the first years of the transition, and then they settle. In research tracking women during perimenopause and menopause, the fat gain and muscle loss sped up, then leveled off about two years after the final phase of the transition.²

Perimenopause vs postmenopause

What you might notice	Perimenopause	Postmenopause
Body fat, especially around your belly	Goes up faster	Stops going up, but stays higher than before²
Muscle	Starts to drop	Ends up lower, unless you keep lifting²
Blood sugar	Gets harder to keep steady	Stays harder to keep steady⁷

Common Questions

Why is it all going to my belly?

Because estrogen helps decide where your body stores fat, and as it goes down, the storage of fat shifts. Fat that used to settle on your hips and thighs now tends to gather around your waist instead. It isn't something you're doing wrong, it's a change in the body's wiring, and it's one of the most common things women notice in this stretch.

I‘m eating the same as always. Why am I gaining weight?

A few things at once. The lost muscle mass was in charge of burning that energy, so even the same diet will make your body gain more weight. There is just not enough muscle as before. At the same time, your body is trading muscle for fat, so more of what you're carrying is fat. The fix isn't eating less and less; it's maintaining your muscles active.

Will I keep gaining weight like this forever?

For most women, no. The fastest changes in weight appear in the few years after the transition ends and settles into a new normal rather than climbing without end.² That's also why the work you put in now, especially strength training, pays off so well: it lands right when the changes occur.

Do I need to eat a lot more protein?

Enough protein helps, since it's the raw material muscle is built from. But you don't need to chase huge amounts. In one trial of postmenopausal women doing strength training, eating more than the standard recommendation didn't build any more muscle than the normal amount did.⁹ Steady, adequate protein alongside the strength work is what moves the needle, not a giant number.

How Your Body Connects to the Rest of You

Your metabolism is not its own system. The same change is going on through the rest of your body, and two other systems are linked to this one.

First, sleep. After a short or broken night, your hunger and blood sugar are off the next day, so a rough night turns into a hungrier, shakier day. The Sleep and Thermoregulation guide covers why sleep falls apart now and how to protect it.

Second, your mind. Stress and low mood quietly steer what you reach for and whether you've got it in you to move, and carry on with your day. The Brain and Nervous System guide picks up that thread.

So looking after your sleep and your stress isn't separate from looking after your weight. support one, and some of the weight lifts off from the others.

That last one is the one we built a product around. Akkermansia Probiotics Complex is a daily Akkermansia muciniphila supplement, the same bacterium the research keeps pointing to for insulin sensitivity.¹⁰ The science is still early, and no capsule replaces the muscle you build or the sleep you protect. Think of it as one more bit of support for a system that's working too hard to keep up, not a shortcut to health.

See Akkermansia Probiotics Complex →

Also in this series:

[ What Is Perimenopause and Menopause: The Brain and Nervous System → ]

[ What Is Perimenopause and Menopause: Sleep and Thermoregulation → ]

← Back to the full guide

*These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.*

References

Pontzer H, Yamada Y, Sagayama H, et al. Daily energy expenditure through the human life course. Science. 2021;373(6556):808-812. doi:10.1126/science.abe5017
Greendale GA, Sternfeld B, Huang M, et al. Changes in body composition and weight during the menopause transition. JCI Insight. 2019;4(5):e124865. doi:10.1172/jci.insight.124865
Geraci A, Calvani R, Ferri E, et al. Sarcopenia and menopause: the role of estradiol. Front Endocrinol. 2021;12:682012. doi:10.3389/fendo.2021.682012
Szeliga A, Chedraui P, Meczekalski B. The impact of the menopausal transition on body composition and abdominal fat redistribution. J Clin Med. 2026;15(2):740. doi:10.3390/jcm15020740
De Jesus AN, Henry BA. The role of oestrogen in determining sexual dimorphism in energy balance. J Physiol. 2023;601(3):435-449. doi:10.1113/JP279501
Pedada D, Garlapati K, Badam R, et al. Taste changes and salivary flow rate disparities in premenopausal and postmenopausal women: exploring the zinc connection. Cureus. 2024;16(6):e62538. doi:10.7759/cureus.62538
De Paoli M, Zakharia A, Werstuck GH. The role of estrogen in insulin resistance: a review of clinical and preclinical data. Am J Pathol. 2021;191(9):1490-1498. doi:10.1016/j.ajpath.2021.05.011
Khalafi M, Habibi Maleki A, Sakhaei MH, et al. The effects of exercise training on body composition in postmenopausal women: a systematic review and meta-analysis. Front Endocrinol. 2023;14:1183765. doi:10.3389/fendo.2023.1183765
Rossato LT, Nahas PC, de Branco FMS, et al. Higher protein intake does not improve lean mass gain when compared with RDA recommendation in postmenopausal women following resistance exercise protocol: a randomized clinical trial. Nutrients. 2017;9(9):1007. doi:10.3390/nu9091007
Depommier C, Everard A, Druart C, et al. Supplementation with Akkermansia muciniphila in overweight and obese human volunteers: a proof-of-concept exploratory study. Nat Med. 2019;25(7):1096-1103. doi:10.1038/s41591-019-0495-2