Testosterone in Women: The Missing Hormone in Healthy Ageing (and Its Impact on Insulin & Metabolism

When we talk about hormones in women, the focus is usually on oestrogen and progesterone.

But there’s a third hormone that is just as important — and often overlooked: Testosterone.

From a functional medicine perspective, testosterone is not a “male hormone.”It is a key hormone for energy, strength, metabolism, and longevity in women.

Testosterone Naturally Declines With Age

Testosterone levels in women begin to decline from the late 20s to early 30s, with a more noticeable drop during perimenopause and menopause.

By the time many women reach their 40s and 50s:

• Levels are often suboptimal rather than truly “deficient”

• Symptoms are frequently dismissed as “normal ageing”

Common signs include:

• Fatigue and low energy

• Reduced motivation and drive

• Loss of muscle tone

• Increased abdominal fat

• Low libido

• Brain fog

These are often hormonal signals — not just ageing

Testosterone as Part of HRT for Optimal Ageing

Modern hormone optimisation is evolving.

While traditional HRT focuses on oestrogen and progesterone, we now understand that:

Testosterone is a critical component of hormone replacement for many women.

When optimised appropriately, testosterone supports:

• Muscle mass and strength

• Metabolic function

• Bone density

• Cognitive performance

• Sexual health

  
  

At Thrive, we view testosterone as:

A key hormone in maintaining vitality, resilience, and long-term healthspan

The Functional Medicine Perspective

Rather than immediately prescribing testosterone, we assess:

• Is production low?

• Is availability reduced (high SHBG)?

• Are upstream hormones impaired?

• Are lifestyle or nutrient factors suppressing levels?

Because in many women, the issue is not just testosterone itself — but the pathway that produces it.

DHEA: The Precursor Hormone

One of the most important — and often overlooked — hormones in this pathway is:

DHEA (Dehydroepiandrosterone)

DHEA is produced primarily by the adrenal glands and acts as a precursor hormone, meaning it can be converted into:

• Testosterone

• Oestrogen

  
  

Why DHEA Matters

DHEA levels:

• Peak in your 20s

• Decline steadily with age

Low DHEA can contribute to:

• Fatigue

• Low libido

• Poor resilience to stress

• Reduced muscle mass

• Suboptimal testosterone levels

  
  

Can Supplementing DHEA Increase Testosterone?

Yes — in the right patient.

DHEA supplementation can:

• Increase available substrate for testosterone production

• Support adrenal function

• Improve overall hormonal balance

However:

• Conversion varies between individuals

• Some may convert more into oestrogen

Dosing must be personalised and monitored

DHEA is not a shortcut — it’s a tool within a broader hormonal strategy

Vitamin D: The Hormone Regulator

Vitamin D is technically a hormone, not just a vitamin — and it plays a significant role in endocrine function.

Vitamin D and Testosterone

Adequate Vitamin D levels are associated with:

• Higher testosterone levels

• Improved insulin sensitivity

• Better immune regulation

Mechanisms include:

• Supporting hormone synthesis pathways

• Reducing inflammation

• Enhancing receptor sensitivity

  
  

Clinical Insight

Many women with:

• Fatigue

• Hair loss

• Hormonal imbalance

…also have low Vitamin D

Optimising Vitamin D can:

• Support testosterone production

• Improve energy

• Enhance metabolic health

The Overlooked Link: Testosterone & Insulin

Testosterone also plays a key role in metabolic function.

1. Muscle and Glucose Control

Testosterone supports:

• Lean muscle mass

• Glucose uptake

• Insulin sensitivity

Low levels → reduced muscle → poorer glucose control

2. Metabolic Impact of Low Testosterone

Can lead to:

• Increased abdominal fat

• Slower metabolism

• Higher insulin levels

Creating a cycle:

Low testosterone → less muscle → insulin resistance → fat gain

3. Balance Is Key

Excess testosterone (e.g. in PCOS) can worsen insulin resistance.

Optimal levels — not high levels — are the goal

The Thrive Approach to Hormonal Optimisation

We take a layered, personalised approach:

1. Comprehensive Testing

We assess:

• Testosterone (total + free)

• SHBG

• DHEA-S

• Oestradiol / progesterone

• Thyroid function

• Vitamin D

• Insulin and glucose markers

  
  

2. Optimise the Foundations

Before prescribing:

• Protein intake

• Strength training

• Sleep

• Stress management

• Nutrient deficiencies (especially Vitamin D, zinc)

  
  

3. Consider Upstream Support

Where appropriate:

• DHEA supplementation

• Vitamin D optimisation

These can sometimes:

Improve testosterone naturally without direct replacement

4. Targeted Testosterone Therapy

If needed:

• Transdermal testosterone

• Carefully titrated dosing

Goal:

• Restore physiological levels

• Improve symptoms

• Support metabolism

5. Ongoing Monitoring

• Hormones

• Symptoms

• Metabolic markers

Testosterone, Body Composition & GLP-1 Medications

For women using GLP-1 medications:

Testosterone helps:

• Preserve muscle

• Maintain metabolic rate

• Improve long-term fat loss outcomes

What Women Notice When Optimised

• More energy and motivation

• Improved strength and tone

• Better fat distribution

• Enhanced clarity and focus

• Improved libido

And importantly:

Better metabolic stability and insulin control

The Bigger Picture: Ageing Well

Hormonal decline is natural.

But how you respond to it determines:

• Your energy

• Your strength

• Your metabolism

• Your quality of life

From a functional medicine perspective:

Testosterone, DHEA, and Vitamin D are part of a wider hormonal network that supports healthy ageing

Final Thought

If you’re feeling:

• Flat

• Tired

• Losing strength

• Struggling with body composition

…it may not just be ageing.

It may be a hormonal system that needs support — not suppression