You may notice that your waist is getting larger, your clothes fit differently, or losing weight seems more difficult than it used to be. For some women, these changes begin in their 40s, around the time of the menopause transition.
Is perimenopause responsible? Does metabolism really slow down? And what can you do to lose excess body fat without sacrificing muscle?
Research provides some important answers, although studies specifically testing weight-loss strategies in perimenopausal women remain limited. Many dietary and exercise recommendations are based on research involving broader adult populations.
Why Does Weight and Body Composition Change During Perimenopause?
Perimenopause is the period surrounding the final menstrual period, characterised by changes in ovarian hormone production and menstrual cycles. It can begin in the 40s, although the timing varies. Under the STRAW+10 framework, perimenopause extends through the first 12 months after the final menstrual period. [1]
One important finding is that changes in body composition and changes in body weight do not necessarily follow the same pattern.
A 2019 analysis from the Study of Women's Health Across the Nation (SWAN) found that, during the menopause transition:
The average annual rate of fat-mass gain increased from approximately 1% to 1.7%.
Lean mass began to decline rather than increase.
Overall weight continued to increase, but its rate of gain did not significantly accelerate at the start of the transition. [2]
This means that body composition can become less favourable without a dramatic change in the number on the scale.
The distinction matters because lean mass includes muscle and other non-fat tissues. A reduction in lean mass cannot automatically be interpreted as an equivalent reduction in skeletal muscle.
Why Does Belly Fat Increase?
The menopause transition is associated with changes in abdominal fat accumulation.
In a longitudinal SWAN Heart Study involving 362 women, visceral abdominal fat increased more rapidly during the two years preceding the final menstrual period. Greater accumulation was associated with less favourable measures of carotid artery health. [3]
Visceral fat is the fat stored around internal organs. Higher levels are associated with cardiometabolic risk.
However, abdominal fat accumulation is influenced by both reproductive ageing and other factors. The menopause transition is not the sole explanation for an expanding waistline.
Does Metabolism Slow Down After 40?
The idea that metabolism suddenly slows down at 40 is not supported by the available evidence.
A large study of daily energy expenditure, published in Science in 2021, found that energy expenditure adjusted for body composition remained relatively stable between approximately 20 and 60 years of age. [4]
This does not mean that everyone's calorie requirements remain unchanged. Changes in body size, lean mass, physical activity and other individual factors can affect energy expenditure.
Importantly, this study was not designed to isolate the metabolic effects of perimenopause. It challenges the idea of an inevitable age-related metabolic collapse, but does not exclude individual hormonal or metabolic changes.
How to Lose Weight During Perimenopause
Weight loss remains possible during the menopause transition. However, the goal should be more specific than simply reducing body weight.
Weight loss is not the same as fat loss. A reduction on the scale can include fat, lean tissue and water. When losing weight, preserving muscle mass and physical function should also be priorities.
The following strategies are supported by weight-management research. Their effectiveness is established mainly in broader adult populations, with more limited direct evidence from perimenopausal women.
1. Create a Moderate, Sustainable Calorie Deficit
Losing excess body fat generally requires a sustained energy deficit, meaning that energy intake is lower than energy expenditure.
The size of that deficit matters. More aggressive restriction may increase the loss of lean tissue and make it harder to maintain adequate nutrition. [5]
Start by reviewing your usual food intake, meal portions and eating habits. A moderate reduction in energy intake, adjusted to individual requirements, is generally more practical than an unnecessarily restrictive diet.
There is no established calorie target that applies specifically to all perimenopausal women.
2. Prioritise Protein
Adequate protein intake is particularly relevant when reducing calorie intake.
A 2024 systematic review and meta-analysis of 47 studies involving 3,218 adults with overweight or obesity found that higher protein intake helped reduce muscle-mass loss during weight reduction. However, the analysis did not demonstrate significant improvements in muscle strength or physical function. [6]
Practical steps include incorporating protein-rich foods into regular meals, such as eggs, fish, poultry, dairy products, tofu, beans or lentils.
Protein requirements depend on body weight, activity, dietary energy intake and health status. There is currently no universally established perimenopause-specific protein target.
3. Include Strength Training
Resistance training can improve strength and support the preservation of lean mass during weight loss.
A 2022 systematic review and meta-analysis found that resistance training, particularly when combined with dietary energy restriction, improved body-composition outcomes in adults with overweight or obesity. [7]
The World Health Organization recommends muscle-strengthening activities involving all major muscle groups on at least two days per week. [8]
A practical approach is to begin with two full-body sessions weekly, gradually increasing resistance as strength improves.
4. Stay Physically Active Throughout the Week
Aerobic activity supports cardiovascular health, physical fitness and total energy expenditure.
WHO recommends 150–300 minutes of moderate-intensity aerobic activity or 75–150 minutes of vigorous-intensity activity per week for adults. [8]
Walking, cycling, swimming and other activities can contribute to this target.
These are general health recommendations rather than a prescription for a guaranteed amount of weight loss.
5. Address Sleep Problems and Menopausal Symptoms
Sleep disturbances, night sweats and hot flushes can affect daily functioning during perimenopause.
Poor sleep may also complicate weight management. Research in adults has identified relationships between sleep duration and energy intake, although evidence specifically demonstrating that treating menopause-related sleep problems produces weight loss is limited. [9]
If menopausal symptoms are repeatedly disrupting your sleep.
How Should You Measure Progress?
The scale provides useful information, but it cannot distinguish fat loss from changes in lean mass or body water.
Consider monitoring:
Body weight as a trend over several weeks.
Waist circumference, measured consistently.
Strength and exercise performance.
Changes in how clothes fit.
These measurements provide complementary information, although none can precisely quantify visceral fat or muscle mass at home.
If you are already at a healthy weight, improving strength, fitness and body composition may be more appropriate than pursuing further weight reduction.
What Does Research Specifically Tell Us About Weight Loss in Perimenopause?
The strongest menopause-specific evidence describes how body composition changes during the transition. There are fewer well-designed intervention trials testing which weight-loss methods work best specifically in this population.
A 2025 randomised trial examined a comprehensive lifestyle programme in 160 women aged 40–55. After six months, the intervention group showed improvements in weight-related and metabolic outcomes. However, more than 45% of participants were classified as postmenopausal at baseline, despite the study's perimenopause-focused title. The results therefore cannot be considered evidence exclusively for perimenopausal women. [10]
Current practical recommendations consequently combine menopause-transition research with broader evidence on nutrition, physical activity and weight management.
The Bottom Line
Perimenopause can affect body composition, including fat accumulation and the proportion of lean tissue, even when overall weight changes relatively little.
Research does not support the idea that turning 40 inevitably causes a sudden metabolic slowdown or makes weight loss impossible.
For women who would benefit from reducing excess body fat, the most defensible approach is a sustainable energy deficit, adequate protein intake, regular resistance training and aerobic activity, alongside appropriate management of menopausal symptoms.
The aim is not simply to weigh less, but to improve body composition while preserving strength and long-term health.
Scientific References
Harlow SD, et al. (2012). Executive summary of the Stages of Reproductive Aging Workshop +10. Menopause.
https://pmc.ncbi.nlm.nih.gov/articles/PMC3580996/Greendale GA, et al. (2019). Changes in body composition and weight during the menopause transition. JCI Insight, 4(5), e124865.
https://doi.org/10.1172/jci.insight.124865Samargandy S, et al. (2021). Abdominal visceral adipose tissue over the menopause transition and carotid atherosclerosis: the SWAN Heart Study. Menopause, 28(6), 626–633.
https://doi.org/10.1097/GME.0000000000001755Pontzer H, et al. (2021). Daily energy expenditure through the human life course. Science, 373, 808–812.
https://doi.org/10.1126/science.abe5017Murphy C, Koehler K. (2022). Energy deficiency impairs resistance training gains in lean mass but not strength: A meta-analysis and meta-regression. Scandinavian Journal of Medicine & Science in Sports, 32, 125–137.
https://doi.org/10.1111/sms.14075Kokura Y, et al. (2024). Enhanced protein intake on maintaining muscle mass, strength, and physical function in adults with overweight/obesity: A systematic review and meta-analysis. Clinical Nutrition ESPEN, 63, 417–426.
https://doi.org/10.1016/j.clnesp.2024.06.030Lopez P, et al. (2022). Resistance training effectiveness on body composition and body weight outcomes in individuals with overweight and obesity across the lifespan: A systematic review and meta-analysis. Obesity Reviews, 23, e13428.
https://doi.org/10.1111/obr.13428World Health Organization. (2020). WHO Guidelines on Physical Activity and Sedentary Behaviour.
https://www.who.int/publications/i/item/9789240015128Tasali E, et al. (2022). Effect of sleep extension on objectively assessed energy intake among adults with overweight in real-life settings. JAMA Internal Medicine, 182, 365–374.
https://doi.org/10.1001/jamainternmed.2021.8098Verma A, et al. (2025). Effectiveness of an Individualized Comprehensive Weight Management Program in Perimenopausal Women: An Open-label Randomized Control Trial. Journal of Mid-life Health, 16, 434–444.
https://doi.org/10.4103/jmh.jmh_205_24
