Why bone loss begins earlier than most women know – and the complete evidence-based approach to protecting your skeleton

The Disease That Announces Itself with a Fracture

Osteoporosis has been called the silent disease – and the name is precisely accurate. Bone does not hurt as it thins. There is no sensation of structural weakening, no warning signal before the first fracture. For the majority of women who develop osteoporosis, the diagnosis arrives not from a routine scan but from a broken wrist after a minor fall, a vertebral compression fracture from lifting, or a hip fracture that, in older women, carries a one-year mortality rate of 20–30%.

Osteoporosis is often asymptomatic in its early stages, as the reduction in bone mineral density typically does not directly impair quality of life. However, osteoporosis-associated fractures significantly diminish health-related quality of life, particularly in older adults. About 54 million people are affected by osteoporosis and bone loss. Some studies suggest that 1 in 2 women and 1 in 4 men aged 50 and older will break a bone because of osteoporosis.

These are not acceptable odds. And they are not inevitable – but only if the right interventions begin at the right time. That time is perimenopause. Not postmenopause. Not when the first fracture happens. Now.

This article explains the molecular mechanisms of bone loss during this transition, the clinical tools for assessing your risk, and the full evidence-based toolkit – from nutrition to exercise to pharmacology – for protecting your skeleton through and beyond the transition.

Part 1: The Biology – How Estrogen Loss Destroys Bone

Bone Is Not a Static Structure

The first thing to understand is that bone is not a fixed, inert material. It is a living tissue in constant dynamic equilibrium between two opposing cell populations: osteoblasts, which build new bone, and osteoclasts, which break down old bone. In healthy young adults, this process – called bone remodeling – is roughly balanced, with old bone removed and new bone deposited at equivalent rates.

Estrogen is the primary molecular guardian of this balance. It operates through multiple simultaneous mechanisms, each of which is disrupted when estrogen withdraws at menopause.

The Molecular Cascade of Bone Loss

The loss of estrogen during menopause significantly increases the rate of bone resorption leading to a decrease in bone mass, resulting in postmenopausal osteoporosis, the most common type of osteoporosis. Estrogen binds with the estrogen receptor to promote expression of osteoprotegerin, and to suppress the action of nuclear factor- κB ligand (RANKL). This inhibits osteoclast formation and bone resorptive activity. Estrogen can also activate the Wnt/β-catenin pathway to increase osteogenesis, promoting mesenchymal stem cell differentiation from pre-osteoblasts to osteoblasts.

In plain terms: estrogen simultaneously suppresses the cells that destroy bone and promotes the cells that build it. When estrogen falls, both protective mechanisms fail. Estrogen deficiency accelerates bone resorption through a rise in pro-inflammatory cytokines (IL-1, IL-6, TNF-α) and RANKL, which promote osteoclastogenesis. Estrogen can promote the production of osteoprotegerin, a decoy receptor for RANKL, thereby preventing RANKL from activating osteoclasts. Furthermore, estrogen promotes osteoblast survival and function via activation of the Wnt signalling pathway.

The scale of bone loss this produces is quantified clearly in the recent literature. Postmenopausal osteoporosis results from decreased estrogen levels following menopause. This estrogen deficiency triggers a rapid phase of bone loss, predominantly in trabecular bone, with an annual rate of 3%–5% over the first 5–10 years.

To contextualize this: losing 3–5% of bone annually means that a woman who enters menopause with normal bone density can develop osteoporosis – clinically defined as bone density 2.5 standard deviations below the young adult mean – within a decade, without any intervention.

When Does Bone Loss Actually Begin? Earlier Than You Think

One of the most important – and most underappreciated – findings in recent bone research concerns the timing of bone loss. It does not begin at menopause. It begins in perimenopause, sometimes years before the final menstrual period.

The PeKnO study confirms a marked decline of the ovulatory rate during perimenopause, which is associated with an increased bone density loss while estrogen levels are still adequate. This work confirms that the sole explanation of estrogen deficiency for bone density loss is insufficient, and that progesterone and the decline in ovulatory frequency play an independent role.

This is clinically significant: bone loss is already underway during the years of irregular periods and fluctuating hormones -even before the hot flushes begin. And it means that the woman who waits until postmenopause to think about bone health has already lost several years of the most critical protective window.

Women have smaller bones and tend to lose bone mass due to hormonal changes around the time of menopause, making them more likely to have osteoporotic fractures. As estrogen levels reduce during the menopausal transition, there is greater bone resorption than bone formation, resulting in decreased BMD and risk of osteoporotic fractures.

Part 2: Knowing Your Risk -The Clinical Assessment Tools

The DXA Scan: The Gold Standard

Dual-energy X-ray absorptiometry (DXA) is the clinical standard for measuring bone mineral density (BMD). It uses a very small amount of radiation to measure mineral content at the hip and lumbar spine -the two sites most predictive of fracture risk at the clinically significant locations (hip and vertebral fractures).

The result is expressed as a T-score – the number of standard deviations your bone density sits above or below the mean bone density of a healthy young adult woman:

• T-score above -1.0: Normal bone density
• T-score between -1.0 and -2.5: Osteopenia (low bone density, increased risk)
• T-score below -2.5: Osteoporosis (established diagnosis)

The United States Preventive Services Task Force (USPSTF) issued updated recommendations in January 2025 recommending that postmenopausal women aged less than 65 years with one or more risk factors for osteoporosis be screened. DXA is indicated if the patient has a substantial risk of fracture based on clinical factors. The USPSTF recommends DXA if the 10-year predicted risk of major osteoporotic fracture according to FRAX without bone mineral density is 8.4% or greater.

For most women, the practical guidance is: request a DXA scan at or shortly after menopause, and certainly before age 65. Do not wait for a fracture.

The FRAX Tool: Your 10-Year Fracture Risk

FRAX -the Fracture Risk Assessment Tool, developed by the World Health Organization – calculates a woman’s 10-year probability of major osteoporotic fracture using clinical risk factors: age, weight, height, prior fracture history, parental hip fracture, smoking, alcohol use, glucocorticoid use, and relevant medical conditions. FRAX now allows the use of trabecular bone score data to help calculate intervention thresholds for major and hip osteoporotic fractures. It significantly improves risk prediction in patients with otherwise borderline FRAX results.

The tool is freely available at shef.ac.uk/FRAX and takes two minutes to complete. Every perimenopausal and postmenopausal woman should know her score.

Bone Turnover Markers: The Early Warning System

Beyond DXA, a blood and urine test panel can identify women who are “fast bone losers” – those whose biochemistry indicates accelerated bone resorption even before DXA shows significant structural loss. For clinical use, the International Osteoporosis Foundation proposed the C-telopeptide of type 1 collagen (CTX) as a biochemical marker of bone resorption and N-propeptide of type 1 procollagen (P1NP) as a marker of bone formation. During menopause and in untreated osteoporosis, bone markers can be increased and indicate high skeletal turnover. Cohort studies show bone loss is greater, and fracture risk is higher as these biomarkers increase.

These markers – CTX and P1NP – are not standard in most routine checkups but should be requested by women who want the earliest possible picture of their bone metabolism. They provide actionable information before bone loss becomes structurally visible on a DXA scan.

Part 3: The Evidence-Based Toolkit -What Actually Protects Bone

1. Calcium: The Foundation That Must Be Built from Food First

Calcium is the primary mineral of bone – it is what gives bone its hardness and density. Its adequacy during menopause is non-negotiable.

The evidence-supported daily intake for postmenopausal women is 1,000–1,200 mg per day from all sources combined(food and supplements). The critical clinical point – one that is frequently misunderstood – is that food-sourced calcium is metabolically superior to supplemental calcium:

The 2021 NAMS position statement recommended that all postmenopausal women should have a balanced diet containing calcium and vitamin D to maintain overall health, including bone health. Calcium is abundant in dairy products, fish, and green vegetables. If calcium intake is insufficient with a regular diet, calcium supplements may be considered.

Food sources providing approximately 300 mg calcium per serving: plain yoghurt (300 mg/200g), milk (300 mg/250ml), canned sardines with bones (300 mg/100g), firm tofu (300 mg/200g), white beans (130 mg/200g). Dark leafy greens (kale, bok choy, broccoli) also contribute meaningfully.

The case for supplementation is most clear when dietary intake consistently falls below 800 mg daily. At that threshold, calcium carbonate or calcium citrate supplementation at 500 mg per day (taken with food for carbonate, or between meals for citrate) fills the gap without the kidney stone risk associated with higher supplemental doses.

2. Vitamin D: The Calcium Partner That Most Women Lack

Vitamin D is the prerequisite for calcium absorption in the gut. Without adequate vitamin D, calcium passes through the digestive system largely unused. It is also directly involved in bone mineralization, muscle function (which affects fall risk), and immune regulation.

Vitamin D plays a crucial role in the absorption of calcium in the intestines, bone health, muscle function, body balance, and reducing the risk of falls. Adequate levels of vitamin D can enhance the response to bisphosphonate therapy in patients with osteoporosis, increase bone density, and prevent fractures. Numerous societies have recommended that adults over 50 intake daily at least 1,000 IU of vitamin D.

Vitamin D deficiency is extraordinarily prevalent -estimated at 40–70% of postmenopausal women in temperate climates. Serum 25-hydroxyvitamin D (25-OHD) testing is the standard measure; the target level for bone health is 50–75 nmol/L (20–30 ng/mL), with many specialists recommending the higher end of this range for women with established osteopenia or osteoporosis.

Supplementation at 1,000–2,000 IU daily is safe, evidence-supported, and inexpensive. In women with confirmed deficiency, a short course of higher-dose supplementation (typically 50,000 IU weekly for 6–8 weeks under medical supervision) is used to restore levels rapidly before transitioning to maintenance dosing.

3. Protein: The Overlooked Bone Nutrient

Protein’s role in bone health is underappreciated and frequently absent from osteoporosis conversations. Bone is not simply mineral – approximately 30% of bone mass is organic matrix, primarily collagen type I. Collagen is a protein, and its synthesis depends on adequate dietary protein.

Evidence shows that adequate protein intake supports both muscle mass (which reduces fall risk through better balance and strength) and directly contributes to bone matrix quality through collagen synthesis. The evidence supports protein intakes of 1.0–1.2 g per kg body weight daily in older active adults for optimal musculoskeletal outcomes.

The muscle-bone axis is clinically important: muscle contraction is the primary mechanical stimulus for osteoblast activation. A woman with sarcopenia (muscle loss) loses the primary mechanical driver of bone formation simultaneously with the hormonal driver. Protein, resistance training, and bone health are one integrated system -not separate concerns.

4. Resistance Training and Impact Exercise: The Mechanical Stimulus Bone Cannot Get from Nutrition Alone

Bone responds to mechanical load – and specifically to load that exceeds what it is accustomed to. This is the fundamental principle of osteogenic exercise: bone adapts upward when load increases beyond the habitual threshold and adapts downward (or simply fails to maintain) when it does not.

It enhances osteoblast activity, reducing osteocyte apoptosis and promoting osteoclast apoptosis to inhibit osteoclast function, suppressing bone resorption. As estrogen levels reduce during the menopausal transition, there is greater bone resorption than bone formation -exercise provides the mechanical stimulus that partially compensates for the lost hormonal stimulus.

The evidence for resistance training at the lumbar spine and hip – the two clinically critical sites – is consistent and robust across multiple systematic reviews and meta-analyses. Compound exercises that load the axial skeleton (deadlifts, squats, overhead pressing, loaded carries) produce the strongest osteogenic stimulus. Loads of 70–85% of one-repetition maximum produce superior bone adaptation compared to lighter loads. Two to three sessions per week is the evidence-supported frequency.

Impact exercise (jumping, hopping, brisk walking, running, stair climbing) adds complementary benefit through ground reaction forces that load the femoral neck and vertebral bodies – the sites of the two most clinically important fractures. For women without severe osteoporosis, a progressive jumping program (beginning with low-impact step-ups and building toward box jumps) has demonstrated significant improvements in femoral neck BMD in clinical trials.

Swimming and cycling – while excellent for cardiovascular health – produce minimal bone benefit because they are non-weight-bearing and generate insufficient ground reaction forces. This is not an argument against them; it is a reason to add, not replace, with osteogenic exercise.

5. Lifestyle Factors That Silently Destroy Bone

Several modifiable behaviors directly accelerate bone loss through mechanisms that are well-established but under-communicated:

Smoking reduces estrogen metabolism, directly suppresses osteoblast function, and is a major independent risk factor for fracture. Women who smoke experience menopause approximately two years earlier – compounding the duration of estrogen deficiency. Cessation is a bone health intervention.

Excessive alcohol (more than 2 units daily) impairs calcium absorption, directly inhibits osteoblast function, increases fall risk through balance and coordination impairment, and – in heavy use -significantly elevates fracture risk. The bone health argument for alcohol reduction mirrors the cardiovascular and symptom management arguments precisely.

Corticosteroids – used for inflammatory conditions (asthma, autoimmune diseases, inflammatory bowel disease) – are the leading cause of secondary osteoporosis. Any woman taking oral or inhaled corticosteroids regularly should have DXA monitoring and discuss bone protection with her clinician.

Excessive sodium increases urinary calcium excretion – for every 2,300 mg of sodium consumed, approximately 40 mg of calcium is lost in urine. In women already struggling to meet calcium targets and losing bone through hormonal mechanisms, chronic high-sodium diets represent a directly addressable bone health risk.

Carbonated soft drinks containing phosphoric acid (regular colas particularly) have been associated with reduced bone density in observational studies, through both direct calcium-phosphorus balance effects and displacement of calcium-rich drinks from the diet.

6. Hormone Therapy: The Most Powerful Bone-Protective Intervention Available

The evidence for menopausal hormone therapy (MHT) as a bone-protective agent is, at this point, incontrovertible. It directly addresses the primary cause of postmenopausal bone loss – estrogen deficiency – at the molecular level.

Impact of menopause hormone therapy, exercise, and their combination on bone mineral density shows that both MHT and exercise independently improve BMD, and their combination produces additive benefits. Oral and intravenous bisphosphonates, denosumab, raloxifene, calcitriol, and HRT can be initiated by primary or secondary care clinicians for the prevention and treatment of osteoporosis.

The timing hypothesis – now the dominant framework in menopause medicine – applies specifically to bone: MHT initiated in perimenopause or early postmenopause, when bone loss is most rapid and the skeleton’s response to hormonal restoration is greatest, produces superior outcomes compared to later initiation. For women already on MHT for vasomotor or mood symptoms, bone protection is a confirmed additional benefit -not a separate consideration.

7. Pharmacological Bone Protection: The Clinical Escalation Pathway

For women with confirmed osteoporosis (T-score below -2.5) or established fragility fracture, lifestyle and hormonal interventions may be insufficient alone. A hierarchy of pharmacological agents exists with strong clinical evidence:

Bisphosphonates (alendronate, zoledronate, risedronate) are the most widely prescribed first-line agents. They work by inhibiting osteoclast activity -preventing bone resorption – and have demonstrated fracture risk reduction of 40–70% at vertebral sites and 25–40% at hip sites in randomized controlled trials.

A systematic review of 37 RCTs with 43,397 patients found that vitamin D and calcium supplementation combined with bisphosphonate therapy was associated with a significantly higher increase in BMD at both spine and femoral neck sites compared to either alone.

Denosumab is a monoclonal antibody against RANKL – directly blocking the molecular pathway activated by estrogen deficiency. It is given as a six-monthly subcutaneous injection and produces greater BMD gains than bisphosphonates in head-to-head comparisons. An important caveat: denosumab requires continuous administration, as discontinuation causes rapid bone loss (“rebound”) unless a bisphosphonate is prescribed immediately afterward.

Anabolic agents – teriparatide, abaloparatide, and romosozumab – stimulate bone formation directly rather than merely inhibiting resorption. The 2024 UK clinical guideline considers teriparatide as a second-line treatment option in postmenopausal women aged 50 and older, and abaloparatide or romosozumab in postmenopausal women intolerant of bisphosphonate treatment, particularly in those with vertebral fractures. Following the approved duration of treatment with these anabolic agents, initiation of an antiresorptive agent without delay is recommended.

Raloxifene is a selective estrogen receptor modulator (SERM) that acts like estrogen in bone (reducing resorption) without stimulating breast or uterine tissue. It is appropriate for women who cannot or prefer not to use MHT and who do not require the greater efficacy of bisphosphonates.

Part 4: The Practical Framework – An Integrated Action Plan

The evidence supports a simultaneous, not sequential, approach to bone protection. Beginning in perimenopause:

Assess: Calculate your FRAX score (shef.ac.uk/FRAX) today. Request DXA if you are postmenopausal with any risk factors, or at age 65 regardless of risk factors. Consider requesting CTX and P1NP bone turnover markers with your next blood test to identify whether you are a “fast bone loser.”

Nourish: Target 1,000–1,200 mg calcium daily primarily from food. Test your serum 25-OHD and supplement vitamin D to maintain levels above 50 nmol/L. Eat adequate protein (1.0–1.2 g/kg body weight). Reduce sodium, alcohol, and cola consumption.

Move: Two to three resistance training sessions weekly at progressive loads targeting compound movements. Add weekly impact exercise – walking at minimum, running or jumping if appropriate for your fitness level.

Protect: Discuss MHT with a menopause-specialist clinician, framing bone protection as a primary indication if you have risk factors for osteoporosis. Stop smoking. Manage corticosteroid exposure with clinical guidance.

Treat: If DXA confirms osteoporosis or osteopenia with high FRAX score, pursue pharmacological treatment guided by a specialist. Do not delay – the bones that are lost in the first years after menopause cannot be fully recovered.

The Bottom Line

The prevalence of osteoporosis will continue to rise as the world’s population ages. Since women’s bones are smaller and thinner than men’s, bone loss accelerates as estrogen levels fall. Bone loss is 3%–5% annually in trabecular bone during the first decade after menopause – a rate that can take a woman from normal bone density to clinical osteoporosis within ten years without intervention.

Bone loss is not inevitable. Fractures are not an unavoidable feature of aging. They are the consequence of a preventable disease that announces itself silently, progresses over years, and responds -meaningfully and measurably – to intervention that begins early.

Perimenopause is that beginning. The skeleton does not wait for symptoms. Neither should you.

For more useful articles and expert guidance, explore the Womeno app – your personal digital companion through the hormonal transition. Download the app HERE

Sources

1. Hsu SH, Chen LR, Chen KH. Primary Osteoporosis Induced by Androgen and Estrogen Deficiency: The Molecular and Cellular Perspective on Pathophysiological Mechanisms and Treatments. International Journal of Molecular Sciences. 2024;25(22):12139. doi:10.3390/ijms252212139
2. Cheng R et al. Menopause-related changes to maxillary trabecular bone micro-architecture. Frontiers in Aging. 2026. doi:10.3389/fragi.2025.1589708
3. Frontera Reproductive Health. Impact of menopause hormone therapy, exercise, and their combination on bone mineral density and mental wellbeing in menopausal women: a scoping review. Frontiers in Reproductive Health. 2025. doi:10.3389/frph.2025.1542746
4. PMC8871419. Perimenopausal Bone Loss Is Associated with Ovulatory Activity -Results of the PeKnO Study. PMC. 2022.
5. PMC12901315. Estradiol regulates osteoclast sialylation via ST3Gal1 in postmenopausal osteoporosis. PMC. 2025.
6. Frontiers in Medicine. Drugs against osteoporosis in perimenopausal and postmenopausal women. 2025;12. doi:10.3389/fmed.2025.1682333
7. Cleveland Clinic Journal of Medicine. To scan or not to scan? DXA in postmenopausal women. ccjm.org. April 2020.
8. Cleveland Clinic Journal of Medicine. DXA and clinical challenges of fracture risk assessment in primary care. ccjm.org. November 2021.
9. Rheumatology Advisor. Screening for Osteoporosis: What Patients Should Know. rheumatologyadvisor.com. February 2026. (Citing USPSTF January 2025 recommendations)
10. USPSTF. Recommendation: Osteoporosis to Prevent Fractures: Screening. uspreventiveservicestaskforce.org. January 2025.
11. JAMA. Screening for Osteoporosis to Prevent Fractures. Accepted December 2024, published January 2025. (USPSTF Evidence Review)
12. PMC11103071. The 2024 Guidelines for Osteoporosis -Korean Society of Menopause: Part I. PMC. 2024.
13. Springer Nature Archives of Osteoporosis. The 2024 UK clinical guideline for the prevention and treatment of osteoporosis. PMC12417299. doi:10.1007/s11657-025-01588-3
14. PMC11836767. Expert consensus on vitamin D in osteoporosis. Annals of Joint. 2025. doi:10.21037/aoj-24-48
15. Springer EJMED. Vitamin D and calcium supplementation in women undergoing pharmacological management for postmenopausal osteoporosis: a level I of evidence systematic review. European Journal of Medical Research. 2025. doi:10.1186/s40001-025-02412-x
16. PMC11617160. Efficacy of combination therapy of vitamin D and bisphosphonates in the treatment of postmenopausal osteoporosis: a systematic review and meta-analysis. Frontiers in Pharmacology. 2024. doi:10.3389/fphar.2024.1422062
17. AdventHealth. Osteoporosis and Bone Density: Who Needs the Screening and When? adventhealth.com. May 2024.
18. Stamford Health. What The Updated Osteoporosis Screening Guidelines Means For You. stamfordhealth.org. March 2025.
19. Nature Bone Research. Aging and menopause reprogram osteoclast precursors for aggressive bone resorption. doi:10.1038/s41413-020-0102-7
20. JNRID. Assessment of diagnostic approach and treatment plan for postmenopausal osteoporosis in women. tijer.org. May 2024.