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Health, Nutrition, Technology

Exercise machine calorie counters: they exaggerate the burn

TreadmillJanuary is the month of the jogger. Every evening for the past three weeks, regular-looking folk have been bouncing their bits up and down our streets, running in the pursuit of getting a bit fitter. No doubt prompted by a New Year’s resolution or ill-considered pledge to run this year’s half-marathon, such noble joggers oftentimes prefer an air-conditioned gym. Away from the wind and snow, the treadmills and ‘cardio’ machines offer music, television and – the greatest motivator of all – the digitised calorie counter. Trundling away on a treadmill while watching ‘Cash in the Attic’ is soul-crushingly dull but the knowledge that twenty minutes of puffing will burn off the a chocolate bar’s worth of calories can help keep your legs pounding. It’s such a shame, then, that the treadmill is lying to you. The truth is that if you want to justify a chocolate indulgence then you’ll probably need to sweat for just a bit longer than the computer tells you.

The way to work out how much energy – or how many calories – you are burning at any given time is far from straightforward. It is usually said that most people burn between about 2,000 and 2,500 calories per day and, while this is a good average, the actual amount for any one individual vary wildly. A small, elderly person may expend as few as 1,300 calories a day whereas a muscular young man could easily burn twice that. Similarly, the amount of energy you use up while exercising will vary according our size, age, gender, weight, body fat and fitness. This means that the burly man who hasn’t exercised in ten years will use up more calories peddling an elliptical trainer on setting ‘10’ than a fit, slim female triathlete will.

Understandably, most exercise machine manufacturers don’t say how they work out their calorie counts. They may claim to use the most up-to-date algorithms but even the best machines that let you input your age, weight and gender usually overestimate by about 10-20% according to most independent tests. For the only way to accurately calculate calories expended is to use lab-based equipment. And out of all ‘cardio’ machines, the elliptical trainer is the least reliable. So at the end of a workout when you think you’ve got through 250 calories, the truth is probably nearer to 200.

Mobile phone apps and fitness watches are increasingly on trend (although I’ve never seen the appeal of enjoying a jog while tracking each stride). But as with the stationary machines, these can be wildly inaccurate. One independent review of the six best-selling fitness trackers showed that – when they were all worn at the same time – the results between devices varied by as much as 100%. (He apparently looked like he’d just escaped from a lab.)

But even if they don’t always tell the truth, he doesn’t mean we should necessarily do away with them altogether. Some research shows that having a calorie score can help us to stay motivated when we want to quit. So, if you find the calorie ticker keeps you going when the nights are miserable, continue to let them drive you. Just don’t take them too seriously, and don’t use them to base your diet on. Your best bet is just take them with a pinch of sugar.

Thanks for reading – all opinions expressed are my own. Feel free to add your thoughts in the comments below.

Photo Credit: Sten Dueland via Compfight cc

About Stuart Farrimond

I love writing about science and health subjects. Strange, because I also teach the same things. I trained as a medical doctor before turning my hand to other things. Shortlisted for The Guardian/Observer for Science Writer of the Year 2011 and editor for Guru Magazine I also like to grow large pumpkins...


One thought on “Exercise machine calorie counters: they exaggerate the burn

  1. hi dr stu,
    i m 34 years old, height 5′ 5″, my weight is 72 kilograms, per day how much calorie should burn for me. please give me an advice.

    Posted by Philips Laws | October 25, 2015, 7:38 am

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