How safe is my fitness tracker data, really?

At a gig this summer, two friends emerged from the mosh pit to move further back in the crowd. One had told the other off. Not for any normal misbehaviour, but for pointing to her smart watch and telling strangers how high moshing had sent her heart rate. We are now surrounded with data generated by our bodies – there’s a better way to live, and we’ve got to have it. 

It is not just heart rates. Thanks to innovations like the Oura Ring, anybody can be subjected to fully quantified pub chat about sleep quality. Amateur runners can train to daunting levels of precision. The step trackers in our phones mean I can tell you that, on 1 August 2025, mine believes I took just 46 steps. Or that on 3 June, I took 51,351 steps. Hangovers and silly trips to the Basque mountains aside, there is value to be had from these insights. What might become of our craving for fitness information – and will it be used for good?  

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Our thirst for numbers can have unintended consequences. Stalkers have used Strava to track their victims, while heatmaps of users’ runs gave away the locations of military bases and spying outposts in 2018. A French newspaper even used the app to identify members of French and Russian security outfits. 

Public concern over what becomes of our data has grown. Polling from YouGov in March 2025 found almost half of those asked (48%) were concerned that companies could use data collected from their devices to learn details about their lifestyle. Meanwhile, research from Boston Consulting Group found that around two-thirds of respondents were comfortable with health data being used to generate profits – though just 6% were happy with no strings attached to those profits. 

Those running the NHS believe there are opportunities. As part of its new 10 Year Health Plan, the government hopes wearable tech will allow patients to manage health conditions at home, with “virtual wards” becoming the norm. Pritesh Mistry, a fellow at The King’s Fund think tank, says this could allow the NHS to become more preventative – picking up when people are already active and allowing them to support that. But it comes with risks. “There’s absolutely concerns around people’s choice in whether they want to use this technology or not. And some people might choose not to, some people might not be able to afford to,” says Mistry, adding this could amount to “digital exclusion, either by choice, or by poverty indicators, or by lack of knowledge and skills”. 

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Mistry adds that wellness data, such as basic heart rate or step count information, is different to health data, such as blood glucose levels, which is treated more strictly under data protection. There are also GP doubts about how effective the data in our pockets and on our wrists is. While wearable tech could motivate people to become more active, it is not as accurate as other ways of measuring health, according to professor Victoria Tzortziou Brown, chair of the Royal College of GPs. She says, “If a patient is concerned about their health because of data produced by a device, this can still provide a helpful starting point for a conversation with their GP about their symptoms. However, general practice does not have the capacity to look through large quantities of wearable data, and we know that sometimes devices can make errors.”  

But our step counts are already seeping into commercial life. Insurer Vitality lets customers earn points based on how many steps they take – at the top level, this can result in a cheaper price come renewal time. “It’s not like they’re harvesting some particularly health-sensitive data. It’s purely how many steps you walked,” says Vlad Shipov, CEO of WeCovr, a firm helping customers buy insurance policies. 

Private medical insurance is on the rise in the UK, and 4.68 million Brits have a private policy. WeCovr say they are now noticing clients from all walks of life wanting to get cover, a shift from a richer customer base around a decade ago, prompted by climbing NHS waiting lists. 

For Mariano delli Santi, legal and policy officer for the Open Rights Group, once commercial incentives get involved, the game changes. Even basic-seeming information can be used to infer more intimate
information – with no guarantees that this information will be used for good. Take addictions, which can show up through compulsive behaviours. 

“In a system where addictions are the easiest thing to see, of course there’s a very big incentive to use this information to exploit your addiction for commercial purposes,” says delli Santi. 

It’s not unimaginable that people could in effect be punished for not wanting – or having access to – tech, reckons delli Santi. “If you say that you don’t want to wear a wearable device, you might end up in a situation where an insurance company decides they don’t have information about you, therefore they’re going to discriminate about you on the basis of nothing,” he says. Equally, he adds, “When there is such an abundance of information, it becomes very easy to have data that can justify whatever decision you want to take about somebody.” 

Do you have a story to tell or opinions to share about this? Get in touch and tell us more. 

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