Testosterone and Bone Density: Why Men Over 40 Need to Think About This Now

Osteoporosis is often framed as a women's problem. Elderly women with fractures dominate the headlines. The truth is quieter and more dangerous: one in five men over the age of 50 will have an osteoporotic fracture in their remaining lifetime. That's millions of men walking around with fragile skeletons they don't know about.

Testosterone plays a central role in maintaining bone density. And if you're over 40, the relationship between your testosterone levels and your skeletal health is something you should actually understand.

The Male Osteoporosis Problem

Men develop osteoporosis later than women (women have a sharp drop in oestrogen at menopause; men have a slow testosterone decline starting around 30). But by 70, many men have severely compromised bone density.

Here's what makes it dangerous: men tend to seek medical care after a fracture. A woman might get bone density screening at 65 and find osteoporosis early. A man breaks his hip at 72 after a fall from standing height, gets a DEXA scan for the first time, and learns his T-score is -3. By then, the damage is decades old.

The fractures themselves are serious: hip fractures in older men are associated with high mortality (about 20% of men die within a year of hip fracture from complications or underlying health decline). Vertebral fractures cause chronic pain and height loss.

Early screening and prevention actually work.

How Testosterone Maintains Bone Density

The mechanism is twofold:

1. Direct action via androgen receptors: Testosterone binds to androgen receptors on osteoblasts (bone-building cells) and stimulates bone formation. More testosterone = more osteoblast activity = more bone laid down.

2. Indirect action via aromatisation to oestradiol: Testosterone converts to oestradiol in bone tissue. Oestradiol is actually more important for bone density than testosterone is. It suppresses osteoclast (bone-breaking-down) activity and promotes oestrogen receptor signalling on bone cells.

This is important: you need both testosterone and oestradiol for healthy male bones. If you're on TRT and your oestradiol is suppressed to near-zero (either from your aromatase being inhibited or from exogenous AI use), your bone density will suffer even if your testosterone is high.

This happens. Men on TRT with very low oestradiol sometimes lose bone density despite "being on testosterone." The reason is the missing oestradiol signal.

The TRT and Bone Density Evidence

Studies consistently show that TRT improves bone mineral density:

• Men with low testosterone who start TRT see increases in lumbar spine and hip bone density of 2-5% per year for the first 2-3 years, then stabilise
• The improvement is modest but real and clinically meaningful
• TRT is actually one of the few pharmaceutical interventions that reliably improves bone density in men

If you have low testosterone and low bone density, TRT is a legitimate therapeutic tool (alongside other measures).

What's a DEXA Scan and When Should You Get One?

DEXA (dual-energy X-ray absorptiometry) is the gold-standard imaging for bone density. It's a quick, painless, low-radiation X-ray that measures the mineral content of your bones.

The score: Your results come as a T-score or Z-score.

• T-score: Compares your bone density to a healthy 30-year-old (peak bone mass). This is what matters for fracture risk prediction.

  • T-score >-1: Normal
  • T-score -1 to -2.5: Osteopenia (low bone density, not yet osteoporotic)
  • T-score <-2.5: Osteoporosis (significantly increased fracture risk)

• Z-score: Compares your density to age-matched controls. Less useful for fracture risk, more useful for identifying secondary causes (e.g., if you're 70 and your Z-score is very low for your age, something else is driving bone loss—maybe hyperparathyroidism, maybe vitamin D deficiency).

Cost in the UK: Private DEXA scans run £100-150. NHS DEXA is free if you meet criteria (high fracture risk, documented low testosterone, history of fracture, on certain medications that affect bone). Many private clinics offer them.

When to get one:

• Age 50+ with any fracture history
• Age 40+ with low testosterone (lab-confirmed)
• Age 40+ if you have risk factors: long-term corticosteroid use, smoking, excessive alcohol, poor nutrition, sedentary lifestyle, family history of osteoporosis
• Before starting TRT (baseline measurement lets you assess whether TRT is working)

Resistance Training: The Primary Lever

Here's the most important statement in this article: resistance training is more important for bone density than any hormone or supplement.

The evidence is overwhelming. Resistance training stimulates bone remodelling through mechanical stress. The bone adapts by becoming denser. This is true across all ages—even men in their 70s and 80s respond to resistance training with measurable bone density gains.

Specific findings:

• Progressive resistance training increases hip and lumbar spine BMD by 1-3% per year in older men
• The effect is larger with progressive loading (continuously challenging yourself with heavier weight) than with static training
• Compound movements (squats, deadlifts, presses) that stress multiple large bones are most effective
• Even modest resistance training (2-3 sessions per week of moderate intensity) provides benefit

Practical implications: If you're 40 and want to protect your bones at 60 and 70, start resistance training now. Not just for muscle, but specifically for bone. Squats, deadlifts, weighted carries, loaded lunges—these are bone-protective exercises.

Calcium and Vitamin D: Required Cofactors

You can't build bone without adequate substrate.

Calcium: Adult men need 1000-1200 mg per day. Most men fall short. Sources: dairy (milk, yoghurt, cheese), leafy greens (kale, broccoli), fortified plant milks, tinned fish with bones (sardines, salmon).

Vitamin D: The evidence for bone health with vitamin D is solid. Vitamin D is needed for calcium absorption and for bone cell function. Most men, especially in northern climates, are deficient.

• Target: 25-OH vitamin D level of 30-50 ng/mL (75-125 nmol/L)
• If deficient, supplement: 1000-2000 IU daily for maintenance, or higher doses (4000-5000 IU) for repletion if you're deficient
• Check your level once—a simple blood test—so you know where you stand

Magnesium: Also important for bone. 400-500 mg/day from diet (nuts, seeds, whole grains, dark leafy greens) is usually sufficient.

Lifestyle Factors That Protect Bone

1. Adequate protein: Bone is made of collagen (protein) plus mineralised matrix. Low protein intake is associated with lower bone density. Aim for 1.6 g per kg body weight if you're training hard.

2. Minimise alcohol excess: Moderate alcohol is fine. Heavy drinking suppresses bone formation and increases fall risk.

3. Don't smoke: Smoking accelerates bone loss.

4. Stay active: Non-resistance exercise (walking, jogging, even just moving throughout the day) also supports bone health, though resistance training is superior.

5. Manage stress: Chronic stress and poor sleep impair bone remodelling. Sleep matters.

What to Do Right Now (Age 40+)

1. If you've never checked your bone density and you're 50+, or if you're 40+ with low testosterone, order a DEXA scan. Cost is modest, and you'll have a baseline to work from.

2. Start or maintain a resistance training programme. This is non-negotiable for bone health. Two or three sessions per week of compound movements (squats, deadlifts, presses, rows) is the evidence-based minimum.

3. Check your vitamin D. Simple blood test. If you're deficient, supplement to 30-50 ng/mL.

4. Hit your calcium target. 1000-1200 mg daily from food first, supplement if needed.

5. If you have low testosterone confirmed on labs and you have osteoporosis or osteopenia, TRT is a reasonable option. Work with your doctor to optimise testosterone without suppressing oestradiol into the basement.

6. Recheck DEXA after 2-3 years on TRT if you started it for bone reasons. You should see modest improvement; if you don't, the TRT protocol might need adjustment.

The Honest Truth

Bone density sounds boring. It's not flashy. But a fracture-free skeleton at 70 is worth incomparably more than the effort to maintain one at 40 and 50.

Resistance training is the foundation. Testosterone helps. Calcium and vitamin D are required. Everything else is secondary. Start now, and you'll thank yourself in 20 years when your mates are nursing fractured hips and you're still climbing stairs normally.

---

Bottom line: Resistance training is your primary bone-protection tool. Calcium, vitamin D, and adequate testosterone are supporting players. Check your density at 50, or earlier if you have risk factors. Build the habit of lifting heavy things now, and your skeleton will be solid in your 60s and 70s.