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Christmas calories – should you trust your fitness tracker?

Enjoying your food at Christmas needn't lead to weight gain - but you need to make sure your fitness tracker is tracking your step count correctly

Christmas calories – should you trust your fitness tracker?

It’s normal to overindulge a bit during the Christmas period – in fact some studies suggest the average Brit consumes two to three times the recommended daily amount of calories on Christmas Day alone. 

Soaring gym memberships, New Year’s resolutions and faithful promises to stick to a new fitness or exercise regime are a common byproduct of a seasonal splurge, and if you’re trying to burn off that festive excess, a fitness tracker or smartwatch can be invaluable to help you stick to your plan.

But what could be the ideal motivational tool won’t be much help if you’re getting mixed messages – inaccurate tracking could be the difference between success and failure.

Data based on British Heart Foundation averages for a mince pie, a 100g portion of Christmas pudding and two chocolates

Best Buy fitness trackers – find out which models aced our accuracy tests

Using your fitness tracker to track calories burned

Most fitness trackers, even the super-cheap ones, will claim to tell you how many calories you’ve burnt off.

You should take this data as a rough guide rather than trusting it too much, though. To properly measure calories, you would need laboratory equipment that analysed your oxygen intake and carbon dioxide production. And, while adults are said to burn on average 500 calories per 10,000 steps, there are many factors at play, including weight, pace, percentage of body fat and age.

Using your fitness tracker to track and increase your step count might be a more useful strategy – all fitness trackers offer this. 10,000 steps is a common goal to aim for, but many trackers allow you to set personalised targets.

If you’re still in festive mode, and not quite ready to hit the gym or pool, increasing your step count is an easy, basic way to get things moving again. The NHS says that ‘walking briskly can help you build stamina, burn excess calories and make your heart healthier’. But keeping track of your progress with a fitness tracker can be touch and go.

Steps taken – what we’ve found

While a fitness tracker can be a great way to regularly monitor a new routine, some simply aren’t accurate enough when it comes to tracking the number of steps you’ve taken. One device we tested was almost 63% out when it came to measuring step count in our testing. Buy a tracker like that and you might think you’ve done your 10,000 steps for the day – but you’ll have only actually done 3,700.

It’s not all bad news, though, as we’ve found some trackers that measured steps with almost no error.

To find out more about the way we test fitness trackers for accuracy, and which are most and least accurate, read our guide to fitness tracker and smartwatch accuracy.

Distance tracking – what we’ve found

You’d need to run two marathons to burn off a 5,000-calorie festive feast, but we’ve found trackers that failed to track distance accurately, too. The graph below shows how far you would have run before the most inaccurate tracker from our tests tells you that you’ve reached the two-marathon mark.

This tracker miscalculated distance by 37%. Use this tracker you might think you’ve covered 52 miles, but you’ll have only actually covered 32.

Some trackers calculate the distance you’ve travelled based on step count (as does the one we’ve highlighted above), while others use GPS. We’ve found that trackers with GPS tend to be more accurate when it comes to calculating distance than ones which base it on steps. GPS has the added bonus of meaning you can leave your phone at home and still track your route.

Not sure which type of wearable to opt for? Read our guide on whether to buy a smartwatch or a fitness tracker.

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