A colleague of mine announced this week, with the particular wistfulness men reserve for discussing their glory days, that during his footballing prime he stood a proud 5 foot 11 and a half inches. He delivered this fact the way other men might mention a war record or a personal best marathon time – chest slightly out, eyes fixed somewhere over your shoulder, on the horizon of his own youth. He is now, he confessed with rather less enthusiasm, under 5 foot 10.

Naturally I did what any reasonable person would do upon hearing a colleague announce he is physically diminishing before our eyes: I went away and researched exactly how worried he should be. The results were more interesting than I expected, and only moderately reassuring.

The numbers, for those keeping score

Here is the unglamorous truth: we are, nearly all of us, on a slow and entirely non-consensual downsizing program from around age 40 onward. The standard estimate has men losing roughly half an inch per decade from that point, accelerating somewhat once you cross 70. Put another way, the long-running Baltimore Longitudinal Study of Aging found men typically lose about 1.2 inches between 30 and 70, stretching to around 2 inches by 80. Women, rather unfairly, tend to lose considerably more – roughly 2 inches by 70 and 3 or more by 80, thanks largely to a greater susceptibility to osteoporosis.

My colleague, by his own arithmetic, has shed a good inch and a half already, and he isn’t even at the finish line yet. Which places him, strictly by the numbers, slightly ahead of schedule – the shrinking equivalent of peaking early. He should perhaps stop announcing his old football height at parties before someone does the maths and asks pointed questions.

Why on earth does this happen?

The mechanics are, depressingly, mostly out of your control. The soft, cushioning discs between your spinal vertebrae – which have spent decades absorbing the indignity of every poorly executed sit-up and ill-advised dance floor manoeuvre – gradually flatten and dehydrate with age. Stack thirty-odd of these small compressions on top of one another and, over a few decades, you have lost a genuinely noticeable slice of yourself. Add in the slow decline of core and postural muscle, a touch of flattening in the arches of the feet, and – in less fortunate cases – the bone-thinning effects of osteoporosis, and you have the full unedifying picture. One eminent Mayo Clinic endocrinologist, asked directly whether there was any way to stop the discs compressing, gave the kind of answer doctors reserve for questions they find slightly amusing: not really, no.

Does any of this actually matter?

Here is where I’ll admit the research took a genuinely sobering turn. A long-term study of British men found that those who shrank by more than about an inch over twenty years weren’t simply cosmetically diminished – they also faced a meaningfully higher risk of dying earlier, and of heart disease specifically. Height loss, it turns out, is less a standalone curiosity and more a general marker of the body quietly falling apart in several directions at once – muscle loss, frailty, cardiovascular decline, all arriving as an ensemble cast rather than solo acts.

The rule of thumb worth remembering, if you’d rather not spend your golden years anxiously measuring yourself against the kitchen doorframe: an inch or so of gradual loss by your seventies is unremarkable. Losing two inches or more, particularly quickly, is a different matter entirely, and a reasonable prompt to mention it to your GP, who may well suggest a bone density scan to rule out osteoporosis before it announces itself more dramatically via a fracture.

Can you actually stop it?

Not entirely, no – the discs are going to do what discs do, and no amount of green juice or willpower will stop the slow, inevitable flattening of your intervertebral cushioning. But you can meaningfully slow the parts of the process that are genuinely pathological rather than simply chronological: weight-bearing exercise, resistance training to preserve the muscle that holds you upright in the first place, adequate calcium and vitamin D, and giving up smoking and heavy drinking, both of which do bone density no favours whatsoever. None of it will get my colleague his missing inch and a half back. But it might stop the process accelerating into something considerably less amusing.

And for those wanting to feel better about their own modest shrinkage

If you want genuine perspective, consider the real extremes. Patients living with severe, longstanding osteoporosis and multiple untreated spinal compression fractures have been documented losing three, four, even up to six inches over the course of their illness – one particularly striking account described a woman going from 5 foot 7 to 5 foot 4 after thirteen separate spinal fractures, an ordeal that also, rather crushingly, leaves people with the distinctive stooped posture doctors call hyperkyphosis, and everyone else has traditionally called a dowager’s hump. Next to that, my colleague’s inch and a half looks like nothing more than a rounding error, and he should, frankly, stop going on about it.

He will, of course, continue going on about it. Men who once stood 5 foot 11 and a half rarely let the matter drop quietly.

Editor’s note: We left this story in inches as that was how the originally measurement was recorded on the football photo.