How to increase testosterone naturally after 40

Most TRT clinics won’t tell you this-because it’s free.

Your body can produce more testosterone. Not by supplementing, not by injecting, not by signing up to a monthly prescription. By removing the things that are suppressing it.

TRT clinics are opening everywhere. Men are being told their testosterone is low, that it’s a natural consequence of aging, and that the solution is pharmaceutical. That’s a profitable narrative. It’s also incomplete.

For a minority of men, TRT is appropriate and necessary. I’ll come back to that. But for the majority of men I see-guys in their 40s and 50s who are carrying 15 to 30 extra kilos, sleeping poorly, stressed, and eating a high-carb diet-the testosterone problem is a lifestyle problem. And lifestyle problems have lifestyle solutions.

I’m 60. I weigh 65 kilograms. My body fat is around 15 percent. My resting heart rate is 39. I run 2.4 kilometres in 9:47. I’ve held that for 15 years through the same approach I teach.

That’s not a sales pitch. That’s what’s possible when you fix the environment.

My testosterone rode along with it too, fine through my forties and most of my fifties. Then at 58 it dropped, and for once the cause wasn’t my lifestyle. I’ll come back to what it was, because it turned out to be the exact situation where TRT is the right call, not the lazy one. More on that later.

What is driving testosterone decline in men over 40?

TRT clinics don’t lead with this: most testosterone decline after 40 is not inevitable. Some of it is age-related. Most of it isn’t.

There are two types of low testosterone. Primary hypogonadism – where the testes themselves fail to produce testosterone regardless of signalling – is a genuine medical condition requiring treatment. It’s less common. Secondary hypogonadism – where the signal from the brain to the testes is disrupted – is far more common, and it responds to lifestyle change.

The main drivers of secondary hypogonadism in men over 40: excess body fat (especially visceral fat), poor sleep, chronic stress and elevated cortisol, a high-carbohydrate diet and insulin resistance, chronic high-intensity cardio, and excessive alcohol. Every one of these is reversible. Most men over 40 presenting with low testosterone are dealing with several simultaneously.

What are the symptoms of low testosterone in men over 40?

Low energy that sleep doesn’t fix. Fat sitting stubbornly around the gut no matter what you cut. Motivation that’s gone missing. Libido that’s dropped off a cliff. Mood that swings low for no obvious reason. Muscle that’s harder to build and easier to lose.

Most men write these off as “just getting older.” They’re not. They’re signals. And they overlap heavily with the symptoms of poor sleep, high cortisol, and insulin resistance – because those three things are usually driving the testosterone problem in the first place.

If that list sounds familiar, don’t jump to a blood test for testosterone alone. Get the full picture first.

How does body fat lower testosterone in men?

Adipose tissue – body fat – contains an enzyme called aromatase. Aromatase converts testosterone to estrogen. The more body fat you’re carrying, particularly visceral fat around the abdomen, the higher your aromatase activity.

This means excess body fat isn’t just a storage problem. It’s an active hormonal problem. Your fat tissue is chemically converting your testosterone into estrogen right now.

Reduce the visceral fat, reduce the aromatase activity. Testosterone rises. Estrogen drops. This is measurable, and I’ve seen it consistently in clients who commit to losing body fat through a low-carbohydrate approach.

Craig, a retired army officer, came to me at 105 kilograms. Four months later he was 90 kilograms. He didn’t touch TRT. He changed his metabolic environment. The hormonal picture followed the body composition change.

How does sleep affect testosterone production in men?

Seventy to eighty percent of your daily testosterone is produced during sleep – specifically during slow-wave sleep and REM sleep.

Shorten your sleep, fragment it, or run on poor-quality sleep for months, and you are directly cutting your testosterone production. Not indirectly, not eventually. Directly, every night. I covered the full hormonal cascade in how poor sleep stops fat loss in men over 40 – the cortisol and testosterone mechanisms are inseparable.

Most men I work with are sleeping six hours or less and calling it fine. It’s not fine. If you’re sleeping six hours and your testosterone is low, you’ve identified a primary lever. Fix the sleep first.

This also explains why men who sort their sleep often see testosterone improvements before any other major change. The production mechanism was always there. It just wasn’t getting the hours it needed.

What does cortisol do to testosterone in men over 40?

Cortisol and testosterone are antagonistic. When cortisol goes up, testosterone goes down. This is structural, not incidental. The cortisol and belly fat article covers this mechanism in full – worth reading alongside this one.

The hypothalamic-pituitary-gonadal (HPG) axis is the signalling pathway that tells your testes to produce testosterone. Chronic high cortisol suppresses that axis. The brain reads elevated cortisol as a signal that the body is under threat, and testosterone production gets deprioritised.

Three things chronically elevate cortisol in men over 40: unmanaged stress, poor diet, and overtraining. That third one surprises people. Men hammering chronic high-intensity cardio – long runs, back-to-back hard sessions, no recovery – are generating significant cortisol load. That suppresses the HPG axis. Chronic cardio at high intensity, without adequate recovery, lowers testosterone.

Strength training two to three times per week with compound lifts does the opposite. It produces an acute testosterone response and doesn’t generate the cortisol burden that repeated high-intensity endurance work does.

What does TRT actually do to your body’s natural testosterone production?

This is the part the clinics skim over.

When you introduce external testosterone, your hypothalamus detects adequate testosterone levels in the bloodstream. It responds the way it’s designed to: it reduces signalling to the pituitary, which reduces signalling to the testes. Natural production slows, then stops.

Your testes, without the signalling they need, atrophy over time.

If you stop TRT, your testosterone doesn’t return to baseline. It drops below where it was before you started, because the production pathway has been dormant. In most cases, that suppression is long-lasting. In some, it’s permanent.

This is not a worst-case scenario. It’s the pharmacology. Once you start TRT without addressing the lifestyle drivers first, you’ve likely closed the door on natural testosterone recovery.

For men with primary hypogonadism, TRT is appropriate and those men need it. But if a man at 48 with 25 kilos of excess body fat, sleeping six hours a night, drinking four nights a week, hasn’t tried fixing any of that – putting him on TRT is not treating his condition. It’s bypassing it at significant long-term cost.

What can men do to increase testosterone naturally before considering TRT?

Six levers. In rough order of impact.

First, lose the visceral fat. This is the biggest single lever. A low-carbohydrate approach lowers insulin, the body shifts to burning stored fat, and as visceral fat drops, aromatase activity drops with it. Testosterone rises. This alone moves the needle more than anything else I’ve seen.

Second, fix sleep. Seven to nine hours minimum. Dark room, cool temperature, consistent schedule. If you’re sleeping under seven hours chronically, everything else you do for testosterone is partial.

Third, reduce alcohol. Ethanol directly inhibits Leydig cell function – where testosterone is produced. It’s not just a cortisol issue. Alcohol hits the production site directly. Read more about the link between alcohol and testosterone here.

Fourth, lower cortisol load. Address chronic stress. Replace chronic high-intensity cardio with two to three sessions per week of heavy compound lifting. Keep insulin stable through diet – blood sugar swings are themselves a cortisol trigger.

Fifth, cut refined carbohydrates and fix insulin sensitivity. Insulin resistance is independently associated with lower testosterone. Fix the insulin environment and the hormonal environment follows.

Sixth, get tested properly – and read the results with context. Total testosterone alone doesn’t tell you what you need to know. Get free testosterone and SHBG (sex hormone-binding globulin) tested too. High SHBG can mean low bioavailable testosterone even when total testosterone sits in the normal range.

What happens when men fix body composition and diet first?

Cameron, a former elite army officer, lost 30 kilograms in three months. That kind of shift in body composition produces measurable hormonal change. That much visceral fat carries a significant aromatase burden – removing it lets the endocrine system do what it’s supposed to do.

Clint reversed his Type 2 diabetes and came off all medication. When you fix the metabolic environment to that degree, the hormonal environment follows. You can’t separate insulin resistance from testosterone suppression in a man who’s been metabolically unwell for years.

Dr. Mark, a GP and competitive cyclist, couldn’t shift his body composition despite maximum-intensity training. Changed the food. 11 kilograms in 12 weeks. The hormonal environment changed with the body composition.

I’ve seen this pattern across 895-plus clients over 15 years: men who fix body composition, sleep, and diet before reaching for pharmaceutical support consistently see testosterone move in the right direction.

What does low testosterone actually tell you about your metabolic health?

Your testosterone level is a report card on your metabolic health.

It reflects your body fat, your sleep quality, your cortisol load, your diet, your training. Fix those inputs and the output changes.

Some men need TRT. If you’ve addressed every lifestyle driver and your testosterone is still clinically low, talk to your doctor about whether TRT is appropriate. That’s a legitimate medical decision.

But most men haven’t done the work. Most men with “low” testosterone at 48 haven’t lost the belly fat, haven’t fixed the sleep, haven’t cut the alcohol, haven’t stopped the chronic cardio. TRT before any of that isn’t optimising your health. It’s skipping the part where you fix the actual problem.

Fix the environment first.

If you want to know exactly what’s going on with your metabolic health before making any pharmaceutical decisions, book a call. That’s the right starting point.

When you do the work and still need help: my own story

Here’s the part I set up at the start.

I did everything in this article, for years. Body composition, sleep, training, alcohol, stress. And in my late fifties my testosterone still fell away.

When I had it properly investigated, the cause wasn’t my lifestyle. Back in my forties, through a long stretch of very high stress, I was found to have a pituitary tumour. The pituitary is the gland that sends the signal telling your testes to produce testosterone. Mine had been quietly compromised for years. That’s secondary hypogonadism from a genuine medical cause, not from neglect.

So at 59, I started TRT. Not as a shortcut. As the correct treatment for a diagnosed medical problem that no amount of clean living was going to fix.

That’s the distinction this whole article balances on. Many men with low testosterone haven’t done the work, and TRT lets them skip it at a long-term cost. A smaller group have done the work, and a real medical cause is still dragging their numbers down. Those men need proper investigation, and sometimes TRT is exactly right. The only way to know which group you’re in is to test properly and have someone read the results who does this for a living.

I work with Dr KJ Lee, who specialises in men’s health. He works with me and with many of my clients right across Australia. He’s the one who helped me get to the bottom of my own numbers, and I recommend him without hesitation.

Here is his clinical note:

From clinical practice, it’s important to know the cause of low testosterone through a blood test. A potential root cause is hypogonadism. It simply means the testes aren’t producing enough testosterone, either because the testes are failing (primary) or because the brain’s signal to the testes, via LH and FSH, is disrupted (secondary). A basic blood panel can show which one you’re dealing with, which is what lets me provide the right solution.

For men worried that testosterone replacement leads to cancer risk down the track: the largest trial to date found no increase in prostate cancer with testosterone therapy versus placebo. The useful takeaway is that total testosterone, free testosterone, SHBG, and LH/FSH read together tell you whether you’re dealing with a reversible, lifestyle-driven picture or a genuine hormonal failure that needs specialist care. That distinction changes everything about what you do next.

— Dr KJ Lee, men’s health GP

Dr Lee’s men’s health initial consult covers the first discussion, a wide range of blood tests, then a follow-up to review your results and provide any scripts needed to improve your health.

Book a men’s health consult with Dr Lee: book here (choose the men’s health initial consult).

Frequently asked questions

How do I increase testosterone naturally over 40?

The highest-impact levers are reducing visceral body fat, fixing sleep to seven-plus hours per night, cutting alcohol, replacing endurance cardio with two to three sessions of compound strength training per week, and reducing refined carbohydrates to improve insulin sensitivity. Do the work on those five things before you consider anything pharmaceutical.

Is low testosterone in men over 40 always age-related?

No. Age accounts for some decline, but most testosterone suppression in men aged 40 to 55 is lifestyle-driven – excess body fat, poor sleep, high cortisol, insulin resistance, alcohol. These factors are all reversible. Age-related decline is gradual and much smaller in men who maintain good body composition and metabolic health.

What are the risks of TRT I should know before starting?

When you introduce external testosterone, your body stops producing it naturally. The HPG axis suppresses. Testicular atrophy can follow. If you stop TRT, your testosterone may drop below pre-treatment levels. TRT is appropriate for men with genuine primary hypogonadism – but it’s a significant commitment with long-term implications. Discuss risks and alternatives with your doctor before starting.

Can losing weight increase testosterone levels?

Yes, directly. Adipose tissue contains aromatase enzyme, which converts testosterone to estrogen. Reducing visceral fat reduces aromatase activity and testosterone rises. This is well-documented and is one of the primary reasons body composition change produces consistent hormonal improvement.

How do I know if I need lifestyle change or specialist medical care for low testosterone?

Get a full panel, not just total testosterone. Total testosterone, free testosterone, SHBG, and LH/FSH read together indicate whether you’re looking at a reversible, lifestyle-driven picture or a genuine hormonal failure that needs specialist treatment. If you’ve addressed body fat, sleep, alcohol, and training and the numbers still don’t move, that’s when to see a men’s health doctor.

How much does sleep affect testosterone?

Between 70 and 80 percent of daily testosterone production occurs during sleep, primarily during slow-wave and REM phases. Chronic sleep restriction cuts that directly – not gradually, not partially. Men sleeping under six hours are running a substantial testosterone deficit from sleep alone. That’s the first lever to fix, not the last.