Brain Health for Women Over 40: Why Lactate Matters

For most of my life, when I heard the word lactate, it was usually in a negative context.

You may remember the old fitness advice.

“Lactic acid causes muscle soreness.”
“Lactate means your muscles are failing.”
“Too much lactate is bad.”

But the science has changed.

In fact, lactate may be one of the most important molecules for brain health for women over 40.

And this is where the work of exercise physiologist Dr Stacy Sims becomes fascinating.

She talks a lot about the importance of producing lactate through exercise, especially for women.

Not just for fitness.

But for protecting the brain.

When we start looking at the science around aging, metabolism, and dementia risk in women, it becomes clear why this matters so much.

 

Why Brain Health for Women Over 40 Deserves More Attention

In Australia, dementia — including Alzheimer’s disease — is now the leading cause of death in women.

Women are also about twice as likely as men to develop Alzheimer’s disease.

This makes protecting brain health for women over 40 an increasingly important conversation.

There are several reasons women may be more vulnerable:

• declining estrogen after menopause
• changes in brain glucose metabolism
• higher risk of insulin resistance
• loss of muscle mass
• increased inflammation

One emerging theory in neuroscience is that Alzheimer’s disease may involve an energy problem in the brain.

In other words, the brain becomes less efficient at using glucose.

When that happens, the brain benefits enormously from having alternative fuel sources available.

Two of those fuels are:

• lactate
• ketone bodies

But they come from very different metabolic pathways.

 

Lactate: The Exercise Fuel That Supports Brain Health

Lactate is produced when your muscles work very hard.

When exercise intensity increases — sprinting, lifting heavy weights, or pushing hard on a bike — your muscles need energy faster than oxygen-based metabolism can provide it.

So your body rapidly breaks down glucose.

This process produces lactate.

For years scientists thought lactate was simply a waste product.

We now know something very different.

Lactate is actually an important fuel and signaling molecule that may play a role in supporting brain health for women over 40.

Once produced by your muscles, lactate enters the bloodstream and travels to several organs:

• the heart
• other muscles
• and the brain

The brain has specialized transporters that allow lactate to cross the blood–brain barrier.

Once inside the brain, lactate can be used directly by neurons as fuel.

But perhaps even more interesting is what lactate signals the brain to do.

 

Lactate and Brain Regeneration

Research suggests lactate stimulates the release of BDNF (brain-derived neurotrophic factor).

BDNF is often described as fertilizer for the brain.

It supports:

• growth of new neurons
• strengthening of neural connections
• improved memory formation
• protection against neurodegeneration

Higher BDNF levels are associated with:

• better cognitive function
• improved learning
• reduced risk of dementia

This is one reason why exercise that produces lactate is increasingly being studied as a strategy for supporting brain health for women over 40.

 

What Exercises Produce Lactate?

Not all exercise produces significant lactate.

Gentle movement is wonderful for health — but it doesn’t create the same metabolic signal.

To produce meaningful lactate, the body needs short bursts of higher effort.

Examples include:

Sprint intervals

Short bursts of fast walking, running, cycling, or rowing.

For example:

30 seconds hard effort
1–2 minutes recovery

Heavy strength training

Compound movements such as:

• squats
• deadlifts
• lunges
• step-ups
• hip thrusts

These exercises recruit large muscle groups and stimulate lactate production.

Hill walking or stair climbing

Even brisk hill walking can generate lactate when intensity rises.

Power movements

Exercises such as kettlebell swings or medicine ball throws recruit fast-twitch muscle fibers that naturally produce more lactate.

These types of exercises help stimulate metabolic pathways that may protect brain health for women over 40.

 

Why This Is Especially Important After Menopause

After the age of 40 — and particularly after menopause — women begin to lose muscle mass more rapidly.

This process is called sarcopenia.

Muscle is not just about strength or appearance.

Muscle is a critical metabolic organ.

It helps regulate:

• glucose metabolism
• insulin sensitivity
• inflammation
• hormone balance

When muscle declines, metabolic health often declines alongside it.

This is why maintaining muscle and producing lactate through exercise may be an important strategy for protecting brain health for women over 40.

 

Where Do Ketones Fit Into Brain Health?

Ketones are another alternative fuel for the brain.

But they arise from a completely different metabolic situation.

Ketones are produced in the liver when:

• carbohydrate intake is very low
• fasting extends long enough
• the body shifts toward fat metabolism

The main ketones are:

• beta-hydroxybutyrate
• acetoacetate

Like lactate, ketones can cross the blood–brain barrier and be used directly by brain cells.

This becomes particularly important because in Alzheimer’s disease, the brain often struggles to use glucose efficiently.

But interestingly, the brain’s ability to use ketones often remains intact.

This is why nutritional ketosis and ketone supplementation are being studied as potential strategies for supporting brain health for women over 40.

 

Lactate vs Ketones: Two Different Tools

It can help to think of lactate and ketones as two different tools.

Lactate comes from intense muscular work.

Ketones come from fasting or fat metabolism.

Both can support brain energy metabolism.

But they arise from different physiological states.

You do not need to be in ketosis to benefit from the brain-protective effects of exercise.

And you do not need extreme exercise to maintain metabolic flexibility.

What matters most for brain health for women over 40 is maintaining the body’s ability to switch between fuels.

 

A Practical Approach to Protecting Brain Health

For many women in the Whole Food Revolution community, the goal is not extreme dieting or extreme training.

It is metabolic resilience.

That might look like:

• strength training two to three times per week
• including occasional bursts of higher-intensity exercise
• maintaining muscle mass
• eating protein-rich whole foods
• avoiding constant snacking
• allowing overnight fasting periods
• supporting sleep and recovery

These habits help the body maintain the ability to use multiple fuels:

• glucose
• fat
• lactate
• ketones

And that flexibility may be one of the most powerful ways to support brain health for women over 40.

 

The Bigger Picture

Protecting brain health after 40 is not about chasing a single molecule.

It is about supporting the systems that keep the brain energized.

Movement.

Muscle.

Metabolic flexibility.

Sleep.

Connection.

Lactate reminds us that sometimes the best thing we can do for our brain is simply move harder for a short time.

And occasionally allowing the body to tap into other fuels — like ketones — can add another layer of resilience.

Your brain is incredibly energy-hungry.

The more flexible your metabolism becomes, the more resilient your brain becomes too.

And that resilience may be one of the most important investments we can make in our long-term health.

Check out the Metabolic Health Content Cluster for more information:

Fasting for Women Over 40: Fuel or Fast?

Circadian Rhythm Eating for Women Over 40

Masterclass in Plant vs Animal Protein: Quality, Carbs, and Balance

Thrive with Aerobic Exercise for Women Over 40