longevitywatch

What happens to your bones when you lie in bed for a long time?

Prolonged bed rest demonstrably leads to substantial bone loss, particularly in the hip, spine and heel bone. Recovery takes much longer than the period of bed rest itself, so resuming movement as soon as possible is the best thing you can do.

Bones are not static tissue. They are constantly being built up and broken down, and that balance depends heavily on movement and load. During prolonged bed rest, that mechanical stimulus disappears. Bone-forming cells become less active, while bone-breaking cells become more active. The result is measurable bone loss, and it happens faster than most people expect.

After 17 weeks of bed rest, healthy men lost an average of 3.9% of bone mass in the lumbar vertebrae and 4.6% in the hip. The heel bone, which normally absorbs a great deal of load, lost as much as 10.4%. Blood markers for bone breakdown rose clearly during bed rest. Researchers observed the same pattern in pregnant women prescribed bed rest: they lost an average of 4.6% of bone mineral in 20 weeks, compared with 1.5% in women who continued to move normally. The chance of losing more than 5% of bone mass was six times as high.

Recovery after bed rest is slow and far from always complete. After 17 weeks of bed rest and six months of being active again, only the heel bone had largely recovered. The spine and hip showed a positive trend but did not return to their previous level. Prevention is therefore far more effective than trying to recover after the fact.

In the long term, this bone loss increases the risk of fractures, particularly in the vertebrae and hip. Vertebral fractures are the most common complication of osteoporosis and can lead to chronic pain and loss of independence. Diet also plays a role: a diet high in animal protein and low in vegetables or fruit was associated with additional bone loss in the lumbar vertebrae during bed rest. Adequate calcium appears to be protective against this.

The evidence
7 studies

Based on multiple human studies, including a controlled 17-week bed-rest study in healthy men, a study in pregnant women, and research into bone markers during bed rest and spaceflight. No large randomised studies on recovery. The strength of evidence is strong for bone loss itself, moderate for recovery and fracture risk.

Last checked: September 2026 · how this was judged
Related answers

What does using steroids (as in sport) do to your bones?

Steroids in sport appear to stimulate bone formation in the short term, but they disrupt your hormonal balance in a way that can actually damage bones. Especially for young people and with prolonged use, the risks are serious enough to avoid.

Does drinking a lot of alcohol weaken your bones?

Chronic heavy drinking demonstrably weakens your bones and substantially raises the risk of a hip fracture; for your bones there is no safe level above two drinks per day.

Do carbonated drinks damage your bones?

Drinking large amounts of sugary soft drinks is associated with lower bone density, but this effect is likely partly due to soft drinks displacing calcium-rich beverages. Limit your intake, especially if you also consume little milk or other calcium sources.

Moderate evidence

Why do bones become more brittle after menopause, and what can help?

Bone loss after menopause is well understood and partly preventable: oestrogen deficiency is at the core, but good nutrition, exercise, hormone therapy and, where necessary, bone medication offer proven protection. Which approach suits you best is something to discuss with your doctor.

Yes · Strong evidence

Can having too little body fat damage your bones?

Too little fat can damage your bones, but muscle mass and the location of fat matter at least as much. If you have concerns about bone health in combination with low body fat, discuss this with your general practitioner or sports medicine physician.

Yes · Moderate evidence

Does taking cortisone long-term weaken your bones?

Long-term cortisone use demonstrably weakens your bones; if you use it long-term, it is wise to discuss with your doctor whether you are a candidate for bisphosphonates as a protective measure.

Related research
29 Sep
Transplanted immune cells donate mitochondria to brain cells
25 Sep
New atlas maps aging in individual kidney cells
21 Sep
A brain protein reverses aging signs in mice
Don't see your question?
Ask it and we'll look it up for you.
Ask a question →
Newsletter

Stay in the loop

Twice a week, the most important longevity research in your inbox.