Your body is not a number: are we worrying about biological age all wrong?

The tyranny of the scales

It’s exhausting being a woman in midlife. Just when you’ve made peace with your weight, somebody introduces another way to assess your health. BMI, cholesterol, body fat, muscle mass and now biological age. At the local gym, the Boditrax machine offered another number: my estimated metabolic age. I half expected it to announce that I was about 100 and suggest I go home for a lie-down. Instead, it produced a detailed body-composition report. Fascinating, certainly, although metabolic age and biological age are different things.

As I increased my strength training, my estimated muscle percentage climbed, which felt like encouragement that those squats were achieving something. It was an estimate, though, rather than proof of precisely how much muscle I had gained. My weight, however, barely moved. Sometimes it increased, while my BMI remained stubbornly unkind. The readings gave me something to consider beyond my weight, provided I resisted treating every fluctuation as a verdict.

I’ve been stepping onto scales for decades. The equipment is now more sophisticated, but I’m not convinced our relationship with it has improved.

When weighing myself became a lunchtime thing

My fascination with scales goes back to my days working at The Journal in Newcastle upon Tyne. A group of us regularly walked to Grainger Market at lunchtime, where someone wrote your weight on a little ticket for 20p. I stapled those tickets into my diary, carefully recording every fluctuation. Eventually, I stopped eating lunch before weighing myself because I worried about the extra weight. I even considered which clothes might produce a more flattering result.

Looking back, I wasn’t measuring my health. I was organising my behaviour around a weekly ritual that had become more important than it deserved. The technology has changed since then, but I suspect many women still recognise that disappointment when the scales refuse to cooperate at whichever slimming group they attend. We grow older and our bodies do change, yet somehow we expect them to look as though we’re still in our twenties.

What my BMI doesn’t know about me

BMI is another measurement that needs context. Calculated using height and weight, it is a useful screening tool, but the NHS explains that BMI cannot distinguish muscle from fat. It does not directly assess cardiovascular fitness, either. Jordan Chadwick, managing director at Tonic, a private weight-loss surgery provider, explains why treating it as a complete assessment can be misleading.

Jordan Chadwick, managing director at Tonic

Chadwick points out that two people with identical BMI readings may have very different levels of muscle, fitness and metabolic risk. Weight and waist measurements still matter when assessing health risks, but they belong alongside other information rather than being treated as the final word. For me, understanding what my body can do has become increasingly important, particularly as I navigate the physical changes that come with midlife. My relationship with these labels has a history, as I wrote in my experience of BMI during pregnancy.

Why strength matters more to me now

At 51, I’m increasingly interested in whether I can lift heavier weights, manage a demanding combat-style class without wondering whether I’ve made a terrible mistake, or keep up with Cyrus. I exercise because I want to maintain the strength to manage everyday life as I get older. On days when a longer session feels difficult, I have also explored five-minute menopause workouts. The NHS physical activity guidelines recommend activities that strengthen all the major muscle groups on at least two days a week, alongside aerobic activity. That gives me a more useful aim than chasing a younger age on a screen. I would rather be capable of carrying the shopping without assistance than spend another decade worrying about fitting into a smaller dress.

When information becomes judgement

I still like looking at my Boditrax results. A graph suggesting my training is paying off is quite persuasive. But I remember those tickets from Grainger Market and how easily curiosity became an obsession. There is a difference between monitoring health and letting measurements dictate how we feel about ourselves. Regular exercise, balanced nutrition, sleep and appropriate health checks deserve my attention. I don’t want the pursuit of a younger-looking number to become another reason to pick my body apart.

My body has carried a pregnancy at 40, given birth, danced, lifted weights, recovered from illness and is juggling perimenopause. It has changed, and I expect it will continue doing so. I want to reach my 60s and 70s with the strength and energy to enjoy them, rather than spend the intervening years trying to reverse the ageing process. I’ll still check my muscle percentage because old habits die hard when accompanied by an attractive graph. But the bathroom scales can continue gathering dust.

What does ageing well mean to you?

Would knowing your estimated biological age help you make useful changes, or give you one more number to worry about?

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