As you move through perimenopause, changes in hormones, declining muscle mass, and shifts in metabolic function begin to occur.
Together, these changes alter how your body regulates energy, stores fat, and responds to training.
You’re now in a different physiological phase – your body no longer responds to food and training the same way.
Understanding how your new physiology works enables you to apply strategies that support fat loss and improve body composition.
Hormonal changes
The primary hormonal changes during perimenopause involve estrogen and progesterone.
Progesterone declines earlier, whereas estrogen fluctuates before gradually decreasing over time.
This results in a less stable hormonal environment compared to earlier years, where hormone levels were more predictable and consistent.
Loss of lean muscle mass
Alongside these hormonal changes, there is a gradual loss of lean muscle mass, which accelerates during perimenopause.
Muscle plays a central role in metabolic function. It influences how efficiently your body uses energy and how it responds to both nutrition and training.
As muscle mass declines, your body becomes less efficient at utilising fuel and requires fewer calories to function.
This directly reduces your resting metabolic rate – meaning your body burns less energy at rest than it did previously.
Muscle also plays a key role in how your body stores and uses carbohydrates. With less muscle available, your capacity to utilise carbohydrates effectively is reduced.
Loss of muscle mass is one of the most significant reasons fat loss becomes more difficult.
Increased cortisol and stress load
At the same time, the body’s response to stress begins to change.
During this stage of life, stress often increases (work, family, ageing parents, disrupted sleep, etc.), and your body’s ability to regulate that stress becomes less efficient.
As a result, cortisol is not only released more frequently, but it also takes longer to return to baseline.
This prolonged elevation of cortisol shifts how your body manages energy:
- Encourages the body to favour energy storage over energy use.
- Promotes the breakdown of muscle tissue to use as energy (which then reduces your capacity to utilise fuel efficiently).
- Increases the availability of glucose in the bloodstream.
It also disrupts appetite regulation, often increasing cravings for quick energy, while further impacting sleep and recovery.
A prolonged increase in cortisol shifts the body towards prioritising fat storage over fat loss.
Reduced insulin sensitivity
Insulin sensitivity refers to how effectively your body responds to insulin and clears glucose (blood sugar) from the bloodstream.
- When insulin sensitivity is high, glucose is efficiently taken up into cells.
- As insulin sensitivity decreases, this process becomes less effective.
More glucose remains in the bloodstream, increasing the likelihood of it being stored rather than used.
To compensate, the body produces more insulin in an attempt to bring blood glucose levels back down.
Over time, this creates an environment where energy is more likely to be stored than used.
Reduced insulin sensitivity creates an environment where fat storage is prioritised over fat loss.
Impaired carbohydrate metabolism
These changes directly affect how your body processes carbohydrates.
- Reduced muscle mass (lower capacity to store and use carbohydrates)
- Elevated cortisol levels (increased circulating glucose and reduced fuel efficiency)
- Decreased insulin sensitivity (reduced ability to clear glucose from the bloodstream)
Carbohydrate metabolism becomes less efficient, particularly in the absence of sufficient muscle mass and appropriate training stimulus.
This reduces your body’s capacity to utilise carbohydrates effectively.
The solution is not to reduce carbohydrates, but to improve your body’s ability to use them.
Why this matters
These hormonal and physiological changes create a very different internal environment compared to earlier years.
Your body is no longer operating under the same conditions, which is why the same approach to training and nutrition often produces different outcomes.
The same inputs no longer produce the same outputs.
What works now
For women 40+, your approach needs to align with your physiology.
This means moving away from doing more, and focusing on what actually supports your body now.
- Building and maintaining muscle.
- Lowering cortisol levels.
- Improving insulin sensitivity.
- Supporting metabolic function.
Without this, progress becomes harder to achieve no matter how consistent you are.
It’s not about doing more – it’s about applying the right stimulus for your new physiology.
If you want help applying this
If you’re ready to stop doing more and start applying what actually works for your body, this is exactly what I guide you through inside my 4 Week Challenge.
You’ll follow a structured plan designed specifically for women 40+, focused on supporting lean muscle, improving metabolic function, and driving fat loss.
No guesswork. Just a specific, science-based program that works with your physiology.
Once she stopped doing more and started applying the right approach for her body, the results followed.