Understanding Insulin Resistance and Weight Changes During Perimenopause

Why Your Body Changes in Midlife—and How Nutrition and Lifestyle May Support Metabolic Health

"I'm eating well, exercising regularly, yet I'm still gaining weight around my middle."

If you've found yourself saying this during your 40s or early 50s, you're certainly not alone.

Many women notice changes in body composition during perimenopause. Weight may gradually shift towards the abdomen, energy levels can fluctuate, sugar cravings may become stronger and maintaining muscle feels more challenging than it once did.

These changes are often frustrating, particularly when your eating habits haven't changed significantly.

The good news is that these changes are not simply about willpower. Perimenopause is a time of significant hormonal, metabolic and physiological change. Understanding what is happening inside the body can help you make informed nutrition and lifestyle choices that support your health.

Understanding Insulin Resistance and Weight Changes During Perimenopause

What is insulin resistance?

Insulin is a hormone produced by the pancreas that helps move glucose (sugar) from the bloodstream into your body's cells, where it is used for energy.

When the body's cells become less responsive to insulin, the pancreas produces more insulin to keep blood glucose within a healthy range. This is known as insulin resistance.

Over time, reduced insulin sensitivity may be associated with:

• Weight changes, particularly around the abdomen

• Increased hunger

• Sugar cravings

• Fatigue after meals

• Elevated blood glucose

• An increased risk of prediabetes and type 2 diabetes

Insulin resistance often develops gradually and may occur for many years before blood glucose becomes abnormal.

Why can perimenopause influence insulin sensitivity?

During the reproductive years, estrogen plays an important role in supporting normal glucose metabolism and insulin sensitivity.

As estrogen levels begin to fluctuate and gradually decline during perimenopause, several physiological changes may occur.

These can include:

• Reduced insulin sensitivity

• Changes in body composition

• Gradual loss of muscle mass

• Changes in appetite regulation

• Poorer sleep quality

• Increased stress and cortisol

• Reduced energy expenditure

These changes vary from woman to woman, but together they may influence how the body stores and uses energy.

Why does abdominal fat increase?

Many women notice that fat begins accumulating around the waist rather than the hips or thighs.

This type of fat, known as visceral fat, surrounds the internal organs and is metabolically active.

Higher amounts of visceral fat have been associated with an increased risk of:

• Cardiovascular disease

• Type 2 diabetes

• High blood pressure

• Metabolic dysfunction-associated steatotic liver disease (MASLD)

• Elevated blood lipids

Supporting metabolic health rather than focusing solely on the number on the scales is often a more helpful long-term approach.

Could insulin resistance be contributing?

Although these signs are not diagnostic, they may be worth discussing with your GP.

Some people notice:

• Weight changes around the waist

• Increased cravings for sweet foods

• Feeling hungry shortly after meals

• Afternoon energy slumps

• Difficulty maintaining weight

• Elevated fasting glucose or HbA1c

• A history of PCOS

• A family history of type 2 diabetes

Appropriate pathology testing can help provide a clearer picture of your metabolic health.

Your gut microbiome may influence metabolic health

Your digestive tract is home to trillions of microorganisms collectively known as the gut microbiome.

Emerging research suggests that the gut microbiome may influence metabolic health through several pathways, including:

• Short-chain fatty acid production

• Gut barrier integrity

• Immune regulation

• Bile acid metabolism

• Appetite-regulating hormones such as GLP-1 and peptide YY

While the gut microbiome is only one part of the picture, supporting a healthy and diverse microbiome may contribute to overall wellbeing.

Ways to support your gut microbiome

Aim to include:

• A wide variety of colourful vegetables

• Legumes

• Whole grains

• Nuts and seeds

• Fruit

• Fermented foods if suitable for you

Many experts recommend aiming for around 30 different plant foods each week to help support microbial diversity.

Don't forget thyroid health

The thyroid gland plays an important role in regulating metabolism and energy production.

When thyroid hormone levels are not optimal, some people may experience:

• Fatigue

• Brain fog

• Constipation

• Feeling cold

• Dry skin

• Weight changes

• Reduced exercise tolerance

If you have symptoms that concern you, discuss appropriate thyroid function testing with your GP.

Nutrition strategies that may support healthy insulin sensitivity

Prioritise protein

Protein supports:

• Muscle maintenance

• Satiety

• Healthy blood glucose regulation

• Recovery after exercise

Including a source of protein with each meal may help you feel fuller for longer while supporting muscle health during midlife.

Examples include:

• Eggs

• Greek yoghurt

• Fish

• Chicken

• Lean meat

• Cottage cheese

• Tofu

• Tempeh

• Legumes

For some people, starting the day with a protein-rich breakfast may support satiety and help maintain more stable blood glucose levels throughout the morning.

Build balanced meals

Rather than focusing only on calories, consider building meals around:

✔ Protein

✔ Fibre-rich carbohydrates

✔ Healthy fats

Balanced meals may support satiety and help maintain more stable blood glucose levels.

Increase dietary fibre

Dietary fibre slows digestion and provides fuel for beneficial gut bacteria.

Aim to include:

• Vegetables

• Legumes

• Whole grains

• Oats

• Nuts

• Seeds

• Fruit

Variety is important because different fibres nourish different gut microbes.

Build and maintain muscle

Resistance training is one of the most effective lifestyle strategies for supporting healthy insulin sensitivity.

Benefits include:

• Improved glucose uptake by muscles

• Preservation of muscle mass

• Support for bone health

• Healthy ageing

Current Australian Physical Activity Guidelines recommend including muscle-strengthening activities at least two days each week.

Prioritise sleep

Sleep plays an important role in appetite regulation and metabolic health.

Poor sleep has been associated with increased hunger, stronger cravings and reduced insulin sensitivity.

Aim for around 7–9 hours of quality sleep where possible.

Manage stress

Long-term stress may influence eating behaviours and metabolic health.

Helpful strategies may include:

• Walking

• Yoga

• Meditation

• Deep breathing

• Spending time in nature

• Social connection

Time-restricted eating

Some research suggests that time-restricted eating may support insulin sensitivity in certain individuals.

One commonly discussed approach is a 16:8 eating pattern, where food is consumed within an eight-hour window and an overnight fasting period of around 16 hours is observed.

For example:

• Finish dinner around 6:00 pm.

• Eat your first meal around 10:00 am the next morning.

• Break the fast with a protein-rich meal.

This approach is not suitable for everyone, and any dietary changes should be individualised and discussed with your healthcare practitioner where appropriate.

Reducing concentrated sources of added sugars

Whole fruit provides fibre, vitamins, minerals and beneficial plant compounds and remains an important part of a balanced dietary pattern for most people.

However, frequent consumption of foods high in added sugars, particularly sugar-sweetened beverages and highly processed foods, may contribute to poorer metabolic health.

Examples include:

• Soft drinks

• Fruit juice

• Desserts

• Sweetened yoghurts

• Breakfast cereals high in added sugar

• Foods containing high-fructose corn syrup

Research suggests that high intakes of added sugars, particularly from sugar-sweetened beverages, may contribute to metabolic dysfunction through multiple pathways, including increased oxidative stress, inflammation and fat accumulation in the liver.

Supporting a healthy inflammatory response

Lifestyle habits that may support a healthy inflammatory response include:

• Eating a variety of colourful vegetables and fruit

• Including omega-3-rich foods such as oily fish, walnuts and chia seeds

• Choosing extra virgin olive oil

• Eating adequate fibre

• Supporting gut microbiome diversity

• Prioritising sleep

• Managing stress

• Being physically active most days

What about supplements?

Nutrition and lifestyle remain the foundation of supporting metabolic health.

Some supplements have been studied in specific populations, but they should complement—not replace—a balanced diet and healthy lifestyle.

Magnesium

Magnesium contributes to normal energy metabolism, muscle function and normal glucose metabolism.

People with inadequate magnesium intake may benefit from increasing magnesium-rich foods, and supplementation may be appropriate in some individuals following assessment by a qualified healthcare practitioner.

Myo-inositol

Research has explored myo-inositol in relation to insulin sensitivity in certain populations, including women with PCOS.

Whether supplementation is appropriate depends on individual circumstances and should always be discussed with your healthcare practitioner.

Practical steps you can start today

✔ Include protein with each meal.

✔ Build balanced meals with protein, fibre and healthy fats.

✔ Eat a diverse range of plant foods.

✔ Stay physically active and include resistance training.

✔ Prioritise sleep.

✔ Manage stress.

✔ Reduce sugar-sweetened beverages and highly processed foods.

✔ Discuss any concerns about blood glucose or thyroid function with your GP.

My approach as a Clinical Nutritionist

Every woman experiences perimenopause differently.

As a Clinical Nutritionist, I take an individualised approach by considering your symptoms, dietary intake, lifestyle, health history, pathology results and, where appropriate, gut microbiome testing.

Rather than focusing on restrictive diets, my aim is to help you build sustainable nutrition and lifestyle habits that support your overall health and wellbeing.

Ready to learn more?

If you're experiencing digestive concerns, thyroid conditions, perimenopause symptoms or would like personalised nutrition guidance, I'd be happy to support you.

Online consultations are available Australia-wide.

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References

• Briden L. Hormone Repair Manual. Chapters on insulin resistance and metabolic health.

• Australian Dietary Guidelines. National Health and Medical Research Council.

• Davis SR, Baber RJ, et al. International evidence on menopause and metabolic health.

• International Menopause Society. Lifestyle recommendations for women during midlife.

• Microba. Educational resources on the gut microbiome and metabolic health.

Disclaimer

This article is intended for general educational purposes only. It is not a substitute for personalised medical advice, diagnosis or treatment. Always consult your GP or another qualified healthcare professional before making significant dietary, lifestyle or supplement changes.