As women enter perimenopause, hormonal fluctuations begin to affect how carbohydrates are metabolised, leading many women over 40 to notice changes in energy, weight, and cravings.
Many women notice that foods they once tolerated well, particularly carbohydrate-rich ones, now seem to contribute to fat gain, energy crashes, or increased cravings. This shift isn’t in your head — it’s grounded in real, measurable changes in hormonal regulation and metabolic function.
In this post, we’ll look at:
- How estrogen influences carbohydrate metabolism.
- What changes occur in perimenopause.
- Why low-carb diets may not be ideal.
- Evidence-based strategies to optimise carbohydrate intake.
How Perimenopause Changes the Way We Process Carbohydrates
When you eat carbohydrates, your body breaks them down into simple sugars, mainly glucose. The glucose is then absorbed into your bloodstream, which can be used immediately for energy or stored in your muscles and liver for later use.
The Role of Estrogen in Carbohydrate Metabolism
Key actions of estrogen in carbohydrate metabolism include:
- Enhancing insulin sensitivity (how effectively our body responds to insulin, which helps shuttle glucose from the bloodstream into our cells).
- Promoting glucose uptake into skeletal muscle.
- Suppressing glucose production in the liver (the liver stores excess glucose, which can then be released back into the bloodstream, AND it can also create new glucose when stores are running low).
This means that under normal estrogen levels, the body manages blood glucose effectively and uses carbohydrates efficiently, particularly during and after physical activity.
What Changes During Perimenopause?
During perimenopause, estrogen and progesterone levels become erratic and begin to decline, which impacts how the body processes and stores carbohydrates.
- Reduced insulin sensitivity: This impairs glucose uptake, leading to higher blood glucose and a tendency to store more glucose as fat.
- Shift in body composition: Loss of estrogen contributes to increased abdominal fat, which produces low-level inflammation, making it harder for insulin to work properly.
- Decline in lean muscle mass: Muscle is a major site for glucose disposal, so reductions in muscle mass reduce metabolic efficiency.
- Altered appetite regulation: Estrogen interacts with appetite-regulating hormones (e.g., leptin, ghrelin), and its decline can lead to increased hunger and carbohydrate cravings.
These physiological changes mean the same carbohydrate intake may now result in higher blood sugar, increased fat storage, and reduced energy stability compared to earlier in life.
Why Low-Carb or Ketogenic Diets Are Not Ideal
While reducing refined carbohydrates is beneficial, extreme carbohydrate restriction is not appropriate for perimenopausal women, especially those who are active.
Potential downsides of very low-carb diets include:
- Increased cortisol levels: When carbohydrate intake is low, the body perceives it as a form of stress, especially if you’re also training hard and not eating enough overall.
- Glucose is the body’s preferred fuel, especially for the brain, red blood cells, and during high-intensity exercise.
- If you’re not eating enough carbs, your body has to make its own glucose, mostly through a process in the liver called gluconeogenesis.
- This process is stimulated by cortisol, so if you consistently eat too few carbs, your body raises cortisol to keep your blood sugar stable.
- Over time, this can lead to chronically elevated cortisol, especially when combined with other midlife stressors (work, family, hormonal shifts, poor sleep, etc.).
- Decreased thyroid function: Your thyroid helps control your metabolism, energy, mood, and even fat-burning. It makes a hormone called T4, which your body needs to convert into T3, the active form that keeps everything running smoothly.
- Your body needs enough carbohydrates to make that conversion happen properly.
- If you go too low-carb for too long, your body may slow down this process as a way to conserve energy, which can lead to:
- Feeling tired or sluggish, slower fat loss, brain fog, and digestive issues.
- Impaired sleep and mood: When you eat carbohydrates, your body releases insulin, which helps clear most amino acids from the bloodstream into the muscles, except for tryptophan. This gives tryptophan a better chance to cross the blood-brain barrier and enter the brain, where it can be converted into serotonin (our feel-good hormone).
- Without carbs insulin release is lower, so the other amino acids remain in the blood and compete with tryptophan to get into the brain.
- This means less tryptophan makes it in, and therefore, less serotonin is produced.
- Serotonin is also used to make melatonin, so if serotonin levels drop, so does melatonin which affects our sleep quality and circadian rhythm.
- Loss of lean muscle mass: Carbohydrates are our body’s preferred energy source. When you don’t eat enough carbs, your body still needs glucose to fuel vital functions, especially your brain and red blood cells.
- If there isn’t enough glucose coming from carbs, your body turns to other sources to make glucose.
- One major source is amino acids from muscle tissue, meaning your body starts breaking down muscle to keep blood sugar stable.
- When you combine: Low carbohydrate intake (leading to muscle breakdown for energy) + Lower estrogen (reducing muscle maintenance), it creates a perfect storm that accelerates the loss of lean muscle mass.
- Losing muscle is a big deal because muscle tissue helps maintain your metabolism: less muscle means your metabolism slows down, making it harder to lose fat and keep energy levels up.
Evidence-Based Strategies for Carbohydrate Intake in Perimenopause
Rather than eliminating carbohydrates, a more effective approach is to optimise the type, timing, and pairing of carbohydrates to work with your physiology.
Prioritise complex, fibre-rich carbohydrates
These support better glycemic control and feed the gut microbiota, which can influence metabolic health and estrogen metabolism.
Examples:
- Vegetables (especially root vegetables and leafy greens)
- Legumes (lentils, chickpeas, beans)
- Whole grains (quinoa, oats, barley, brown rice)
- Low-glycemic fruits (berries, apples, citrus)
Time carbohydrates around exercise
During and after exercise, skeletal muscle increases glucose uptake independently of insulin. Consuming carbohydrates post-workout can:
- Enhance glycogen resynthesis
- Support recovery
- Improve insulin sensitivity
Combine carbohydrates with protein and fat
This slows the digestion and absorption of glucose, reduces blood sugar spikes, and increases satiety. For example:
- Oats + Greek yogurt + chia seeds
- Sweet potato + grilled chicken + avocado
Moderate intake, don’t eliminate
Carbs aren’t the enemy!!! When used wisely, they can actually help you lose fat, sleep better, and improve mood and cognition.
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