Why You Feel More Tired in Perimenopause - and How Creatine Can Help

Wondering why your energy feels all over the place? Why workouts feel harder, recovery takes longer, or your brain just can’t keep up some days?

You’re not imagining it.

Perimenopause brings about major biological changes, and one of the most affected systems is your body’s ability to produce and recycle energy at the cellular level. At the centre of it all is ATP—your body’s main energy currency. Understanding how perimenopause impacts ATP helps explain those frustrating symptoms, and shows why creatine might be an unexpected but powerful ally.

ATP: Your Body’s Energy Engine

ATP (adenosine triphosphate) powers everything from muscle contractions and nerve signals to thought processes and metabolism. But here’s the catch: your body stores only a tiny amount of ATP and must constantly regenerate it.

This continuous production is often called the ATP energy loop, and during perimenopause, this loop comes under stress.

What Changes During Perimenopause?

Perimenopause is a time of fluctuating and gradually declining oestrogen. While most of us associate oestrogen with reproduction, it also plays a crucial role in energy metabolism, particularly in the brain and muscles.

When oestrogen becomes unpredictable—sometimes high, sometimes low—it causes instability across your body’s energy-producing systems.

How Oestrogen Supports ATP Production

Let’s break down how oestrogen influences energy:

1. Mitochondrial Function

Oestrogen regulates your mitochondria, your cells’ power plants. As oestrogen declines, mitochondrial efficiency drops, and ATP production becomes less effective.

2. Brain Glucose Metabolism

Your brain depends on glucose, and oestrogen helps neurons absorb and use it. Without that support, your brain may enter an “energy crisis” phase - cue brain fog and fatigue.

3. Muscle Energy and Recovery

Oestrogen supports muscle repair and creatine storage. As it drops, we lose muscle mass and our ability to quickly regenerate ATP during physical exertion declines.

The “Energy Gap” Explained

These hormonal shifts create what researchers call a bioenergetic gap - a mismatch between energy demand and supply.

You might notice:

• Faster physical fatigue

• Slower post-exercise recovery

• Reduced strength or stamina

• Mental fog and sluggishness

• That irresistible 3pm sugar or caffeine crash

It’s not in your head. It’s a real, physiological response to hormonal shifts - not laziness or lack of motivation.

Where Creatine (and Fuel) Fits In

Creatine plays a key role in your phosphocreatine system—the body’s fastest way to regenerate ATP, especially during times of high energy demand (like exercise, stress, or intense focus).

It works by donating a phosphate group to ADP, rapidly regenerating ATP without needing oxygen.

During perimenopause—when both mitochondrial and glucose systems are under strain—this quick energy system becomes even more vital.

Creatine and Muscle Energy

We naturally lose muscle mass as we age, but this accelerates during perimenopause. Since creatine is primarily stored in muscle, less muscle = lower creatine reserves.

Supplementing with creatine may:

• Increase phosphocreatine availability

• Boost power and endurance

• Improve training quality and outcomes

• Speed up post-exercise recovery

Studies show that creatine combined with resistance training leads to greater strength and lean mass gains in midlife and older women.

Creatine and Brain Energy

Despite only being ~2% of your body weight, your brain uses ~20% of your energy. During perimenopause, this demand increases just as oestrogen support declines.

Creatine helps by:

• Increasing brain phosphocreatine stores

• Supporting ATP regeneration in neurons

• Improving cognitive resilience under stress and fatigue

A randomised controlled trial in peri- and postmenopausal women showed creatine supplementation improved reaction time and mood stability, while increasing brain creatine levels.

Why Creatine Is Especially Helpful in Perimenopause

Several factors make creatine particularly valuable for women over 40:

• Women have naturally lower creatine stores than men

• Creatine intake often drops with age (especially on plant-based diets)

• Muscle mass declines, reducing creatine storage capacity

• Our mental and physical energy demands remain high

Unlike caffeine or stimulants, creatine doesn’t mask fatigue—it supports your body’s ability to meet energy demands at a cellular level.

Is Creatine Safe?

Creatine monohydrate is the most well-studied and widely recommended form. At daily doses of 3–5 grams, it’s proven to:

• Increase phosphocreatine stores

• Be safe for long-term use in healthy adults, including women and older adults

• Be effective for both physical and cognitive performance

As always, those with existing kidney conditions should consult their healthcare provider.

What Creatine Can and Can’t Do

Creatine is not a hormone replacement therapy. It won’t stop perimenopause—but it can help reduce energy-related symptoms, such as:

• Physical fatigue

• Poor exercise tolerance

• Brain fog

• Slower recovery

It works best alongside:

• Strength and resistance training

• Adequate protein intake

• Prioritising sleep (hello Reboot)

• Stress management tools

Supporting energy in perimenopause isn’t about pushing harder - it’s about rebuilding the systems that produce and protect your energy in the first place.

References

1. Brinton, R. D. (2009). Estrogen-induced plasticity from cells to circuits. Trends in Pharmacological Sciences, 30(4), 212–222.

2. Mosconi, L., et al. (2017). Menopause impacts human brain structure, connectivity, and energy metabolism. Scientific Reports, 7, 8990.

3. Phillips, S. K., et al. (1993). Muscle strength and estrogen. Journal of Applied Physiology, 74(5), 2154–2158.

4. Chilibeck, P. D., et al. (2015). Effect of creatine supplementation on muscle mass and strength in older women. Journal of Aging and Physical Activity, 23(4), 558–565.

5. Glaser, T., et al. (2023). Creatine supplementation and brain creatine in peri- and postmenopausal women. Menopause, 30(9), 1031–1040.

6. Kreider, R. B., et al. (2017). Safety and efficacy of creatine supplementation. Journal of the International Society of Sports Nutrition, 14, 18.