Strong Bones: What Your Skeleton Really Needs

You can't see your bones in the mirror. You don't feel them while you train, and when they're running low on something, they don't complain. That's exactly why they get overlooked, until the bill arrives decades later. Your skeleton isn't a fixed frame: it's living tissue, rebuilt every day. And you have more say in how it holds up than most people realise.

For context: in Germany, around 2.15 million people aged 35 and over live with an osteoporosis diagnosis, and among women over 90 that figure approaches 30% (WIdO health atlas). Sounds like a topic for later in life? Only half. How strong your skeleton is at 70 depends heavily on what you ask of it today.

Your skeleton is a building site that never closes

Bone is living tissue, constantly being rebuilt: cells called osteoclasts remove old bone material while osteoblasts lay down new. Until roughly 30, the build-up wins. By 18, around 90% of your peak bone mass has been accrued (Pediatrics 2014), and it peaks between 25 and 30 (bone ageing model). From there, the balance slowly tips the other way.

From midlife onwards, the average person loses around 3% of their cortical bone mass per decade, and 7 to 11% of the spongy tissue inside (Physiology of Bone Loss). For women, the menopause years add a faster phase: the spine loses roughly 2% of its density per year, the hip a little over 1%, and that accelerated phase lasts for years (SWAN study).

So there are two dials you can turn: how high your peak is, and how fast you lose it afterwards. Both respond to what you do, and it's never too late to start turning them.

Why your bones love load

Bone adapts to what you ask of it. Give it strong, fast forces and it gets denser and sturdier. Leave those out and it wastes away. What matters is the size of the forces and how quickly they arrive, not how long you're moving. A few intense bouts a week do more than hours of gentle, steady effort (LIFTMOR trial).

The clearest evidence comes from a programme called LIFTMOR: women with low bone density trained twice a week for 30 minutes over eight months, using heavy compound lifts (deadlift, squat, overhead press) plus impact work. Their lumbar spine bone density rose by 2.9%, while the control group lost 1.2%. Injuries? None worth noting (JBMR 2018). In the men's counterpart, LIFTMOR-M, spine density rose by around 4% (JBMR 2020).

An honesty check: on average, exercise effects on bone density are moderate, and not every programme delivers (Osteoporosis International 2023). But the pattern is consistent: heavy resistance work plus impact produces the strongest effects, while walking and steady cardio programmes barely move the needle (review of exercise types, Cochrane review).

There's a second effect that matters just as much with age: strength training builds muscle and sharpens balance and reaction. A Cochrane analysis of more than 23,000 participants found exercise cuts the rate of falls by around a quarter (Cochrane 2019). And falls are what actually break bones.

What this means for your training

• Lift twice a week, 30 to 40 minutes. Big movements such as squats, deadlifts, rows and overhead presses, with a barbell, dumbbells or machines. 2 to 4 sets of 5 to 8 reps, where the last reps feel genuinely hard. Add weight once your technique is solid. New to lifting? Our guide to strength training for beginners walks you through the first weeks.
• Add impact if your body tolerates it. Hopping, skipping, jumps onto a low step. A few sets a week is plenty to start with.
• Ease in. Even in the LIFTMOR trial, the heavy lifting began after a month of technique practice. It doesn't have to be perfect; it has to be regular.
• Keep moving otherwise. Walks and everyday movement are the foundation for your heart, your head and everything else. For bone density specifically, you need the load on top.
• For parents and grandparents: strength plus balance work, ideally supervised. Research points to that combination as the most effective way to prevent falls and fractures (Cochrane 2019).

If your joints or back are complaining right now, this piece on keeping joints strong covers how to train around them.

Calcium: the material you top up daily

Almost all of the calcium in your body sits in your bones and teeth (DGE). Germany's nutrition society recommends around 1,000 mg per day for adults; the US reference values sit in the same range, at 1,000 to 1,200 mg (NIH/ODS).

If intake stays low for long, the body takes what it needs from your bones. Over time, bone mass shrinks and bones become fragile (DGE).

The best sources are milk and dairy. Good contributors also include green vegetables such as broccoli, kale and rocket, plus seeds and nuts. Mineral water with more than 150 mg of calcium per litre can make a real contribution too (DGE).

Vitamin D: the door opener for calcium

Absorbing calcium is one thing. Getting it into your bones needs vitamin D: it regulates uptake from the gut and the mineralisation of bone (DGE).

Your body makes 80 to 90% of its vitamin D itself, with help from sunlight. Food contributes only 10 to 20% (BfR). The DGE's reference value is 20 micrograms (800 IU) per day when your skin isn't making any (DGE).

That scenario is more common than you'd think: in Germany, only about 44% of adults reach a desirable vitamin D level, and roughly 15% are low enough to be at risk of deficiency (BfR).

In practice: get sun on your face and arms whenever it's out. In winter your skin can't make vitamin D at these latitudes, and for risk groups the DGE and BfR point to 20 micrograms (800 IU) a day as a guide (BfR). For more on what vitamin D does beyond your bones, read our article on vitamin D.

Protein and bones: the calcium-thief myth

You may have heard the warning: too much protein leaches calcium from your bones. It comes from older observations where high-protein diets increased calcium excretion. The newer evidence paints a different picture. Reviews find no sign that eating more protein harms bone; in older adults, some even see benefits, especially when calcium intake is adequate (review, meta-analysis).

That fits with the fact that bone is about a third protein by mass (review). For your skeleton, protein is building material, not a villain. Just make sure the calcium comes along with it.

Rounding out your supply on busy days

Some weeks are packed: little sun, rushed meals, training skipped. Your skeleton notices the long-term pattern, not a single day. On days when everything slips, a simple addition helps.

FitLine Restorate Citrus is an evening drink with high-quality calcium, magnesium and vitamin D, plus trace elements such as selenium, copper, manganese and chromium. It takes two minutes to mix and delivers calcium and vitamin D, two of the nutrients this article keeps coming back to, plus magnesium. Not a substitute for training and proper meals, but a convenient backup for the days when both fall through.

What to take away

• Load matters. Two strength sessions a week with progressive weight are the single best investment in your skeleton. Impact work adds to the stimulus if you tolerate it.
• Top up calcium. Around 1,000 mg a day, from dairy, green vegetables, nuts, seeds and calcium-rich mineral water.
• Keep an eye on vitamin D. Get sun when you can, and think about 20 micrograms a day through the darker months.
• Protein is fine. It doesn't harm your bones, and alongside enough calcium it may help them.

Start with one thing: two lifting sessions a week. With every bit of progressive load, your foundation gets a little sturdier, and it will carry you for decades.