7 Reasons You’re Gaining Weight During Perimenopause (And How to Get Back on Track)

7 Reasons You’re Gaining Weight in Perimenopause (And How to Get Back on Track)

If you’re in your 40s or early 50s and struggling with unexpected weight gain, especially around your midsection, you’re not alone. Thousands of women across the United States and in other countries report weight gain in perimenopause, even when maintaining their usual food intake and exercise routines. The truth is, it’s not just about calories—it’s about the hormonal changes your body is going through.

As a functional medicine physician and dietitian, I work closely with women every day who are navigating the complex and often frustrating transition of perimenopause and menopause. I’ve dedicated my YouTube channel and blog to this critical—but often overlooked—stage of life, because it remains underrepresented in both medical research and clinical care. One of the most common and distressing concerns I hear from women in my practice is unexpected weight gain. But this isn’t just about appearance or chasing an ideal body image—it’s about reclaiming health, confidence, and a sense of well-being.

This guide outlines the top 7 reasons for weight gain in perimenopause and menopause, and offers practical, hormone-friendly strategies to support your healthy weight goals.

Please note this article contains affiliate links.  I only recommend products that I use myself or with my patients.  Always discuss any natural health product with your practitioner before starting it as this is not considered medical advice. 

1. Hormonal Imbalance & Fluctuating Estrogen Levels

During perimenopause, estrogen and progesterone fluctuate erratically. These hormonal shifts cause changes in fat distribution, commonly increasing visceral fat (the fat surrounding your internal organs) and belly fat. This isn’t just a cosmetic issue — excess fat mass around your midsection can be associated with metabolic disorders, diabetes, and an increased risk of cardiovascular issues.

The Connection Between Hormones and Weight Gain: Why you gain weight in perimenopause

Role of Estrogen in Body Fat Distribution

Estrogen plays a big role in regulating metabolism and fat distribution. As estrogen levels decline during the later stages of perimenopause, your body undergoes significant changes in how and where it stores fat.

Before perimenopause, estrogen helps distribute fat to your hips, thighs, and buttocks. This is why weight gain in these areas is more common in the early stages of perimenopause, when estrogen dominance is likely to occur.  In the later stages, With less estrogen circulating in your system, fat storage shifts predominantly to your abdominal area, creating that frustrating “menopause belly” many women experience.

Hormonal Changes Leading to Increased Abdominal Fat

The hormonal imbalance during perimenopause doesn’t just affect estrogen. Other hormone levels change too, creating a perfect storm for weight gain:

• Declining estrogen in later perimenopause and menopause leads to increased fat storage, particularly visceral fat around your organs, while spiking and rollercoastering estrogen in the early stages of perimenopause can lead to weight gain around the hips and thighs.
• Fluctuating testosterone levels can affect muscle mass and metabolism
• Rising cortisol from stress exacerbates belly fat accumulation
• Changes in insulin sensitivity can lead to increased blood sugar issues and fat storage

These hormonal shifts combine with a naturally slower metabolism as you age, making it easier to gain weight and harder to lose it. The result? Many women notice an increase in body fat and a decrease in lean body mass, even without changing their diet or exercise habits.

What to do:

• Consider hormone testing to assess estrogen, progesterone, and testosterone levels.  Check out my blog on female hormone testing to learn more!
• If you are in estrogen dominance, support estrogen detox pathways with cruciferous vegetables, fiber, and supplements like DIM and Calcium D Glucarate.
• If you are in late perimenopause or post menopause, talk to a healthcare professional about whether menopausal hormone therapy is right for you.  Or consider hormone-balancing supplemental blends like FemGuard Balance or Happy Mammoth Hormone Harmony (and save 10+% with this link)

2. Insulin Resistance and Blood Sugar Dysregulation

Lower estrogen levels can impair insulin sensitivity, making it harder to manage blood sugar and easier to gain weight. This is one reason postmenopausal women are at greater risk of developing type 2 diabetes.

Estrogen plays a key role in regulating how the body processes glucose, so when estrogen declines, the body becomes less efficient at using insulin to move glucose into the cells. As a result, blood sugar levels can rise, and the body is more likely to store excess glucose as fat—particularly in the abdominal area. This shift not only makes it harder to lose weight or maintain a healthy weight, but it also increases the risk of developing insulin resistance and eventually type 2 diabetes.

This is one of the key reasons why postmenopausal women are at greater risk for metabolic conditions. The combination of hormonal changes, reduced muscle mass, and sometimes a more sedentary life (this can be common due to the fatigue and joint pains that can happen) creates a perfect storm for weight gain and blood sugar instability. Understanding this connection helps explain why traditional weight loss advice doesn’t always work for women in midlife—and why a targeted, hormone-aware approach is better.

What to do:

• Reduce processed carbohydrates and added sugars.
• Eat a balanced diet high in fiber, lean proteins, and healthy fats.
• Try tracking macros to better understand your food intake.
• Engage in regular exercise that improves insulin sensitivity, like walking or strength training.
• Eat most of your carbohydrates in the earlier part of the day and structure your afternoon and evening meals around healthy proteins, non-starchy veggies, and healthy fats. Avoid breads, pastas, rice, and other low-fiber carbs later in the day.

3. Loss of Lean Body Mass and Slower Metabolism

Starting in your 30s and accelerating during perimenopause, you can begin to lose lean body mass, which reduces your basal metabolic rate and energy expenditure (how many calories your body burns at rest and how much you burn during exercise). This shift means that even if your calorie intake stays the same, you may gradually gain extra weight.

What to do:

• Incorporate weight training 2-3 times per week, 25-30 minutes per session.
• Ensure adequate protein to support muscle retention, and/or to support shifting your body fat into muscle.  Typically, you need half your body weight in ounces of protein at a minimum, and more if you are doing the recommended exercise.  A good goal for most women is 20-30 grams of protein per meal when eating three meals per day.
• Don’t slash calories drastically — this can further slow your metabolism and convince your body you are in starvation mode.

4. Poor Sleep, Night Sweats, and Hot Flashes

Hormonal fluctuations during perimenopause often lead to symptoms like night sweats and hot flashes, which contribute to poor sleep. Sleep deprivation can slow your metabolism, increase your appetite hormones, and cortisol, increasing the likelihood of weight gain.

What to do:

• Prioritize getting enough sleep with a consistent sleep routine.
• Avoid alcohol
• Avoid screens before bed.
• Support relaxation with magnesium glycinate, l-theanine, or even melatonin, which declines as we get into our 40s and beyond.  Adaptogenic herb blends can also be helpful- here’s one I use quite often with my patients. 
  

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    or this blend with L-theanine and GABA. 
  

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5. Too Much Cardio, Not Enough Strength Training

While aerobic exercise is important, excessive cardio can elevate cortisol and contribute to muscle loss. In perimenopausal women, this can backfire and lead to increased fat mass.  This is why it may be important for women to not try and exercise longer- but more tailored to what their body needs in this stage.

What to do:

• Prioritize weight training and shorter HIIT type workouts or other interval training to build lean body mass.
• Use aerobic exercise like brisk walking, light jogging, cycling, or swimming for cardiovascular benefits and try to keep it to 45 minutes or less per session.  It may also help to try and train using a smart watch that can track your heart rate, and aim for a goal in Zone 2.
• Avoid overtraining; stress management is essential.

6. Poor Gut Health and Ultra-Processed Foods

An imbalanced gut microbiome can affect hormone metabolism and appetite regulation. Ultra-processed foods spike blood sugar and promote fat storage while reducing microbial diversity (i/e, making for a poor gut environment and an unhappy balance of good to bad bacteria).

What to do:

• Eat a whole-food, high-fiber diet with probiotic-rich fermented foods.  Aim for 30-35 grams of fiber per day.
• Avoid processed snacks, additives, and artificial sweeteners.  If you don’t recognize the word as something natural and from the earth and/or the product ingredients label has more than 5 ingredients, it might be too processed.
• Read labels and look for a carbohydrate-to-fiber ratio of 10:1 or more (at least 1 gram of fiber for every gram of carbs on the nutrition label).
• Support gut health with targeted probiotics and small changes to increase fiber intake.  I have been seeing great results with the SEED Ds-01 Probiotic– it has synergistic prebiotic boosting polyphenols, an incredible and unique blend of probiotics, and enhanced absorption!
  

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7. Stress, Mood Swings, and Lifestyle Burnout

Lifestyle factors like chronic stress, mood swings, poor sleep, and the pressure to do it all can lead to elevated cortisol, reduced motivation and energy to exercise, and emotional eating.

What to do:

• Build in time for self-care and recovery.  Explore techniques like deep breathing, gentle yoga, meditation, journaling, nature walks, epsom salt baths, or other routines that bring you peace and decompression.
• Choose gentle movement like yoga or walking if you’re burned out vs more intense exercise that raises cortisol levels or depletes you.  Listen to your body and ensure you feel energized and not depleted after your exercise.
• Work with a coach or healthcare professional who understands the hormonal and psychological challenges of this life phase.  This is key- many women get blown off by their doctors, or their providers might not understand the significance of what they are feeling, or even know how to help.  Women are often offered an antidepressant instead of diving into a perimenopause or menopause discussion.

Final Thoughts

Weight gain in perimenopause is common, but it’s not inevitable. With the right support, you can improve your body composition, energy levels, and overall health.

Focus on nutrition, movement, mindset, and hormone health — not just losing pounds, but gaining strength, clarity, and resilience.

Resources:

• Check out my YouTube channel here!

• Download my free hormone-balancing checklist! Head over to DrShelleyMeyer.Com and sign up for my email list to have access to all of my free pdfs!

• Helpful posts on this site:

• Estrogen Dominance and Gut Health: How to Heal Both Naturally
• Taming the Cortisol and Perimenopause Chaos: Lifestyle Hacks to Bust Belly Fat

DrShelley

Dr. Shelley Meyer is a board-certified family physician and Institute of Functional Medicine-certified functional medicine physician, as well as a Registered Dietitian. She is passionate about helping women navigate the roller coaster of perimenopause and postmenopause.  She has her own Functional Medicine Practice in Denver, Colorado.