Why women are at higher risk of osteoporosis

Why female bones are more at risk

Female bone biology has specific features that make osteoporosis more common in women. The reasons are both structural and hormonal.

Women start with less bone

On average, women have smaller bones than men, even adjusting for body size. Peak bone density, reached in the late twenties, is typically lower in women. This means women start adult life with less bone in the bank to draw on across the decades. The size difference is not the main driver of osteoporosis risk, though it contributes.

Oestrogen is bone protective

Oestrogen helps maintain bone density throughout reproductive years by influencing the balance between bone formation and bone breakdown. While oestrogen levels are healthy, this balance favours maintaining bone density. The protective effect explains why bone health is generally stable from the twenties through to perimenopause.

Menopause changes everything

When oestrogen falls at menopause, the protective effect disappears. Bone breakdown outpaces bone formation. Women typically lose around 10 to 20 percent of bone density in the 5 to 7 years following menopause. This is the steepest period of bone loss in female life and accounts for most of the gender gap in osteoporosis rates.

Other contributors

Pregnancy and breastfeeding draw on calcium reserves, though most of this is recovered. Eating disorders and very low body weight during reproductive years can permanently affect peak bone density. Some medical treatments including long term steroid use accelerate bone loss. Family history influences risk significantly.

The years that matter most

Bone density is built earlier in life than people realise. The window for building peak bone density closes by the late twenties.

Adolescence is critical

Around 90 percent of adult bone density is achieved by age 18. The teenage years are when most bone building happens. Nutrition, weight bearing exercise and regular periods all contribute. Restrictive eating during adolescence, leading to delayed periods or amenorrhoea, can permanently affect peak bone density. The investment made in adolescent bone health pays off for the rest of life.

The twenties consolidate

Bone density continues to build modestly through the early twenties, reaching its peak around age 25 to 30. Continued weight bearing exercise and adequate nutrition support this final consolidation. Smoking, excessive alcohol and disordered eating during these years still affect peak density.

Thirties and forties maintain

Bone density is broadly stable through these decades while oestrogen is healthy. Active maintenance still matters. Strength training, walking, adequate calcium and vitamin D and avoiding smoking all support continued bone health. Women who become inactive through these years lose bone earlier than those who remain active.

After menopause

Bone loss accelerates dramatically. The first 5 to 7 years after menopause are when most age related bone loss happens. Active intervention during these years through HRT, exercise and nutrition can significantly slow the loss. Speak to your GP about your individual bone health if you have risk factors.

Protecting bone health

Bone health responds to specific interventions. The combination of nutrition, exercise and where appropriate medication produces the best outcomes.

Weight bearing exercise

Bones respond to mechanical loading. Walking, running, jumping, climbing stairs and any activity where you carry your own weight against gravity stimulates bone density. Swimming and cycling are good for cardiovascular health but do not build bone significantly because they do not load the skeleton. A mix of activities supports overall health, with weight bearing specifically for bones.

Strength training

Lifting weights stimulates bone density through the forces transmitted from muscles to bones. Strength training is one of the most underused interventions for female bone health. Two to three strength sessions weekly through the decades makes a substantial difference to bone density and to fall risk in later life. Many women only start strength training in their fifties or beyond. Starting earlier is better. Starting later still helps.

Calcium and vitamin D

Adequate calcium and vitamin D support bone health throughout life. UK reference intake for calcium is 700 mg daily for adults. Vitamin D supplementation of 10 micrograms daily is recommended in autumn and winter for all UK adults. These nutrients alone do not prevent osteoporosis but inadequate intake worsens bone loss.

HRT and medications

Hormone replacement therapy significantly slows bone loss after menopause. For women at high risk of osteoporosis or with established bone density loss, specific osteoporosis medications including bisphosphonates may be appropriate. Speak to your GP about whether bone density assessment or treatment would be appropriate for your situation.

Bone density testing and risk

Bone density can be measured directly through scans. Knowing when this is appropriate helps catch problems early.

Who needs a scan

DEXA bone density scans are typically offered to women with risk factors including previous fragility fractures, early menopause, long term steroid use, low body weight, strong family history of osteoporosis or specific medical conditions that affect bones. Routine screening for all postmenopausal women is not standard in the UK, though some women request private scans.

What the scan shows

The DEXA scan measures bone mineral density and produces a T score comparing your density to peak adult density. T scores between -1 and -2.5 indicate osteopenia (some bone loss). T scores below -2.5 indicate osteoporosis. The Z score compares your density to others your age. Together the scores inform treatment decisions.

Acting on results

Osteopenia warrants attention through lifestyle, calcium, vitamin D and where appropriate HRT. Osteoporosis warrants specific osteoporosis treatment in addition to lifestyle factors. Speak to your GP about what your bone density results mean and what action makes sense for your situation. Repeat scans typically happen every 2 to 5 years.

Risk assessment tools

The FRAX tool used by GPs estimates 10 year fracture risk based on multiple factors including age, weight, smoking, alcohol, family history and bone density if known. The score helps inform treatment decisions. Knowing your fracture risk allows better targeted intervention. Speak to your GP if you want to know your fracture risk estimate.

More on female health

For the nutrient foundation, our Why Calcium and Vitamin D Matter for Women covers the key bone nutrients. Why Strength Training Matters for Women covers the most impactful intervention. And Menopause: A Complete Guide covers the life stage that most affects bone loss.