Metabolism library
Perimenopause and metabolism: why can your body start to feel different?
Perhaps you are eating much as you always have, but your body seems to be responding differently.
Weight may be gathering more easily around your middle. Your energy may feel less predictable. Sleep may be disrupted. You may feel less strong than you once did, or find that approaches that previously helped you manage your weight no longer seem to have the same effect.
It is tempting to put all of this down to “a slowing metabolism”.
The reality is more interesting.
Perimenopause does not simply switch your metabolism off. Hormonal change happens alongside ageing, changes in muscle, sleep, activity, appetite, stress and lifestyle — and together these factors can influence body composition and metabolic health.
Understanding those connections can help you focus on what may actually be useful rather than simply eating less and exercising more.
In brief
Perimenopause is a period of hormonal transition, not metabolic failure.
During this stage of life:
- changing ovarian hormones may influence where fat is stored
- fat mass can increase and become more centrally distributed
- maintaining muscle becomes increasingly important
- disrupted sleep may affect appetite, energy and glucose regulation
- physical activity and everyday movement can change
- insulin sensitivity and cardiovascular risk factors deserve greater attention in some women
- nutrition needs to support muscle, bone and metabolic health rather than simply reduce calories
The important point is that these changes are not identical in every woman.
Your health history, genetics, medication, activity, sleep, diet and existing metabolic health all matter too.
First: what do we mean by metabolism?
Metabolism is often described as how quickly you “burn calories”, but it is much broader than that.
Your metabolism includes the thousands of chemical processes that allow your body to:
- convert food into usable energy
- build and maintain tissues
- store and release energy
- regulate blood glucose
- manufacture hormones and other molecules
- repair cells
- maintain body temperature
- keep organs functioning
So when we talk about metabolic health during perimenopause, I am interested in much more than body weight.
I am also thinking about:
muscle, blood glucose, insulin, fat distribution, cardiovascular markers, sleep, movement, nutrition and how these factors interact.
What changes during perimenopause?
Perimenopause is the transition leading up to menopause, during which ovarian hormone production becomes more variable.
Eventually, oestrogen and progesterone production decline as menopause is reached.
These hormonal changes can produce familiar symptoms such as changes in menstrual cycles, hot flushes, night sweats and sleep disruption. NICE recommends that menopause care is individualised because symptoms, priorities and treatment choices differ between women.
But the hormonal transition is happening at the same time as another process:
ageing.
That distinction matters.
If body composition changes at 45, 50 or 55, we cannot automatically attribute the whole change to menopause.
Age, activity, sleep, muscle mass, food intake, alcohol, stress, medication, genetics and health conditions may all contribute.
Perimenopause can change where fat is stored
One of the more consistent findings in menopause research is a tendency towards greater central fat accumulation.
This means that even when the number on the scales has not changed dramatically, body shape may change.
Research across the menopausal transition has found increases in measures including waist circumference, total fat and visceral fat, alongside changes in lean mass.
This helps explain a comment I hear reflected in many women's concerns:
“My weight hasn't changed that much, but my body has.”
That distinction is important.
Body weight alone cannot tell us how much of the body is:
- muscle
- fat
- bone
- water
or where fat is being stored.
Why does visceral fat matter?
Visceral fat is the fat stored deeper within the abdominal cavity around the internal organs.
It is different from subcutaneous fat, which is stored underneath the skin.
Higher levels of central and visceral fat are associated with a less favourable cardiometabolic profile, which is one reason waist distribution deserves attention alongside total body weight. Research has repeatedly linked the menopausal transition with a tendency towards more central fat distribution.
This does not mean that gaining weight around your middle during menopause automatically means you have a metabolic disorder.
It means it may be useful to look at the wider picture.
[Explore: What is visceral fat and why does it matter? →]
Muscle becomes increasingly important
One of the most useful shifts we can make in midlife is to stop thinking only about losing weight and start thinking about preserving and building muscle.
Muscle is not simply there to make us stronger.
It is metabolically active tissue and plays an important role in glucose disposal and metabolic health.
Across ageing and the menopausal transition, maintaining lean mass can become more challenging, and recent research continues to show lower lean and skeletal-muscle measures after menopause compared with earlier reproductive stages.
The encouraging part is that muscle responds to what we ask it to do.
Resistance training has been shown to improve strength and body composition in middle-aged and postmenopausal women, and meta-analytic evidence supports improvements in lean body mass.
NHS menopause guidance also specifically recommends strength and resistance exercise as part of looking after health through menopause.
Connect the dots
Less muscle + less movement → lower demand for glucose and energy
whereas:
using and building muscle → supports strength, function and metabolic health
This is why I am much more interested in helping women protect muscle than simply chasing a lower number on the scales.
[Explore: Why muscle matters for metabolic health and healthy ageing →]
What about insulin resistance?
Insulin is a hormone produced by the pancreas.
One of its important roles is helping glucose move from the bloodstream into cells where it can be used or stored.
Insulin resistance describes a situation in which cells become less responsive to insulin, meaning the body may need to produce more insulin to achieve the same effect.
The relationship between menopause itself and insulin resistance is not as simple as it is sometimes presented online.
Research suggests that ageing, increasing central fat, physical activity, body composition and hormonal change can all be involved, and some earlier research concluded that the independent effect of menopause on insulin resistance appeared relatively modest.
That is why I prefer not to say:
“Menopause causes insulin resistance.”
A more accurate question is:
What is happening to this woman's metabolic health as she moves through midlife?
For one person, glucose regulation may be excellent.
For another, we may see increasing waist circumference, raised triglycerides, an elevated HbA1c or other metabolic changes that deserve attention.
Context matters.
[Explore: What is insulin resistance? →]
Sleep can change the metabolic picture
Sleep disruption is extremely common during the menopausal transition.
Night sweats, hot flushes, anxiety, life pressures and changes in sleep itself may all contribute.
Poor sleep matters beyond feeling tired the following day.
It can affect appetite, food choices, motivation to exercise and glucose regulation.
This creates an important chain of connections:
menopausal symptoms → disrupted sleep → greater fatigue → less movement / different food choices → potential metabolic consequences
That doesn't mean poor sleep automatically causes weight gain.
It means sleep deserves a place in the conversation rather than treating nutrition and exercise as though they happen in isolation.
NICE recognises sleep problems among menopausal symptoms and includes treatment approaches for menopausal symptoms within its current guidance.
Has your metabolism actually slowed?
This is where language matters.
Energy expenditure can change as we age, particularly if we lose muscle or become less active.
But describing this simply as:
“Menopause slows your metabolism”
misses too much.
The evidence suggests that both ageing and the menopausal transition contribute to changes in body composition, energy balance and fat distribution.
For many women, everyday movement may also quietly decline.
You may still exercise three times a week but:
- sit for longer
- walk less
- have a more sedentary job
- feel too tired to move as much
- recover differently
- have less muscle than ten years ago
Those changes matter too.
Rather than asking only:
“How do I speed up my metabolism?”
I think the more useful questions are:
How well are you maintaining muscle?
How much are you moving across the whole week?
How is your sleep?
What is happening with your appetite and food intake?
How is your metabolic health?
Nutrition through perimenopause
There is no special “menopause diet” that every woman needs to follow.
What matters is building a pattern of eating that supports the priorities becoming increasingly important in midlife.
Protein
Protein provides the amino acids required to build and maintain body tissues, including muscle.
As preserving muscle becomes more important, I look carefully at whether someone is eating sufficient protein and, importantly, how it is distributed across the day.
That does not mean everyone needs protein shakes or an extremely high-protein diet.
The appropriate amount depends on the individual, including body size, activity, health status, diet and goals.
Fibre and plant foods
Vegetables, fruit, pulses, wholegrains, nuts and seeds can contribute fibre and a wide range of nutrients.
Rather than focusing on one “superfood”, I am generally more interested in the overall quality and diversity of someone's diet.
Fibre-containing foods can also help support digestive and cardiovascular health as part of a balanced dietary pattern.
Carbohydrate quality and context
Carbohydrates are not automatically a problem during menopause.
The more useful questions are:
What type?
How much?
What is it eaten with?
How active is the person?
How is their glucose regulation?
A meal containing carbohydrate alongside protein, fibre and fat creates a different nutritional context from consuming highly refined carbohydrate on its own.
There is no reason to assume every woman in perimenopause needs a low-carbohydrate diet.
Dietary fats
Fat is an essential part of the diet.
Rather than trying to make food “low fat”, I am interested in the type of fat being consumed and the wider dietary pattern.
Foods such as olive oil, nuts, seeds and oily fish can form part of a cardiometabolically supportive pattern of eating.
Eating less is not always the most useful first strategy
When body weight begins to change, the instinct is often to reduce food further.
Sometimes total energy intake does need attention.
But repeatedly cutting calories without considering protein, muscle, activity, sleep and food quality can be counterproductive to the wider goal of healthy ageing.
My focus is not simply:
How can we make the body smaller?
It is:
How can we improve body composition while supporting muscle, metabolic health, nourishment and a way of eating you can actually maintain?
Those are not always the same objective.
Movement: think beyond “burning calories”
Exercise has value far beyond the calories displayed on a watch.
Regular activity supports cardiovascular health, bone health, strength and physical function, and exercise interventions can improve body composition in postmenopausal women. Evidence suggests aerobic and resistance exercise can contribute in somewhat different ways, with resistance work particularly relevant to maintaining or increasing muscle.
The NHS specifically recommends regular exercise through menopause, including resistance and weight-bearing activity.
I like to think about movement in three layers:
Everyday movement
Walking, taking stairs, standing, gardening and simply spending less of the day sitting.
Cardiovascular exercise
Activity that challenges the heart and lungs.
Resistance training
Providing enough challenge to the muscles to encourage them to remain strong and adapt.
You do not have to become a gym enthusiast.
But muscle needs a reason to stay.
What I look at when working with women through midlife
There is no single “menopause metabolism test”.
Instead, I bring together different pieces of information.
Your symptoms and health history
What has changed?
When did it change?
Are you experiencing menopausal symptoms?
Are there existing diagnoses, medications or family-history considerations?
Your diet
Not simply calories.
I look at meal structure, protein, fibre, dietary diversity, eating patterns, alcohol and how food fits into everyday life.
Your movement and muscle
What exercise do you do?
Do you resistance train?
How much do you move outside formal exercise?
Your sleep and stress
Both can materially change how achievable nutrition and exercise recommendations are.
Your existing health results
Depending on your situation, existing GP or NHS blood results may already provide useful information.
These could include markers such as glucose, HbA1c, lipids or thyroid investigations where clinically appropriate.
Body composition
Sometimes weight tells us very little.
Waist measurement, muscle, fat distribution and changes over time can provide a more useful picture.
Additional testing
I do not believe every woman in perimenopause needs extensive functional testing.
Additional testing should answer a useful question and ideally change what we do next.
More data is not automatically better care.
Jo's perspective
When a woman tells me that her body has suddenly stopped responding in the way it used to, I don't start by assuming she needs to eat less.
I want to understand what has changed around the same time.
Has sleep deteriorated?
Has activity fallen?
Has muscle been lost?
Has appetite changed?
Are there new metabolic or thyroid markers to consider?
Has perimenopause coincided with a particularly stressful period of life?
What does her current diet actually look like?
My approach is to bring those pieces together before deciding where attention is likely to be most useful.
Because the goal isn't to fight your changing body.
It is to understand it well enough to work with it.
What can you realistically focus on?
You do not need to overhaul everything at once.
For many women, useful foundations include:
- eating enough protein to support muscle
- including plenty of fibre-rich plant foods
- resistance training regularly
- maintaining everyday movement
- supporting sleep where possible
- reducing long periods of inactivity
- considering alcohol intake
- looking beyond body weight to waist, strength and metabolic markers
- reviewing relevant medical issues rather than assuming every symptom is menopause
The priorities will be different for different women.
When should you speak to your GP?
Not every change in midlife is caused by perimenopause.
Speak to your GP or another appropriate healthcare professional if you have symptoms that are new, persistent, severe or concerning, or if you are unsure whether they are related to menopause.
Medical assessment may also be important where there are concerns relating to thyroid function, diabetes, cardiovascular health, abnormal bleeding or other medical conditions.
Nutritional therapy should complement appropriate medical care rather than replace it.
Connect the dots
Perimenopause and metabolism sit at the centre of several important health conversations.
Continue exploring:
What is insulin resistance?
Understand how insulin and glucose regulation work and why context matters.
[Read the guide →]
What is visceral fat?
Why where we store fat may tell us more than body weight alone.
[Read the guide →]
Why muscle matters in midlife
Explore the relationship between muscle, strength, glucose regulation and healthy ageing.
[Read the guide →]
Understanding blood glucose and HbA1c
What these markers tell us — and what they don't.
[Read the guide →]
Want to understand your own metabolic picture?
Your Body Library is designed to help you understand the science.
But a webpage cannot tell you why your body is changing.
If you would like personalised support, I can help you look at your nutrition, lifestyle, health history, symptoms and relevant results together and identify the areas that may deserve attention.
[Explore nutritional therapy →]
[Book a discovery call →]
This page is for educational purposes and does not provide medical diagnosis or treatment. If you have symptoms or health concerns requiring medical assessment, please speak to your GP or another appropriate healthcare professional.
References & further reading
- NICE. Menopause: identification and management (NG23). Current UK clinical guidance on menopause assessment and management.
- NHS. Things you can do to help menopause and perimenopause.
- Ambikairajah A et al. Fat mass changes during menopause: a meta-analysis. Menopause. 2019.
- Kapoor E et al. Weight Gain in Women at Midlife: A Concise Review of the Pathophysiology and Strategies for Management. Mayo Clinic Proceedings. 2017.
- Moccia P et al. Body weight and fat mass across the menopausal transition. 2022.
- González-Gálvez N et al. Resistance training effects on healthy postmenopausal women: systematic review and meta-analysis. 2024.
- Thomas E et al. The effect of resistance training programmes on lean body mass in postmenopausal and elderly women: a meta-analysis. 2021.