Hannah Fry on getting fit: tech empowers us, but data alone doesn’t tell the full story | The Formula To Life With Hannah Fry

There have been a number of meticulous weight watchers in history, but Santorio Santorio is probably the most interesting. Back in the 1500s, he dedicated his life to monitoring his body, weighing both everything he put into it … and everything that came out.

For one particular scientific exploration, he invented what he called a Sanctorean weighing chair – a seat set up next to a dining table, on a steelyard balance, which strictly monitored body weight.

By eating and drinking as much as the body had discharged – which he measured in urine, faeces and sweat, or what he called “insensible perspiration” – he claimed this would allow people to maintain the same weight. Here’s the kicker: once it had been determined that you’d eaten too much, the chair would drop you down so you could no longer reach the food at the table. “As a consequence,” he explained at the time, “all the food and drink would get out of reach, thus sanctioning the end of the meal.”

Although his idea was widely mocked at the time, Santorio was on to something: there is something deeply appealing about an individual, experimental and quantitative approach to our health.

Almost two centuries later, Benjamin Franklin read about Santorio and was inspired to both write down everything he ate, and make a list of all his 13 virtues. He then marked them off each time he committed an immoral act; monitoring and quantifying his life, a minutiae at a time.

Back to the modern world, with the aid of technology, there are people who have gone above and beyond to record their lives. Like a Reddit user who made a beautiful visualisation of data of his baby’s sleeping and waking times in the first few months of her life. The image starts when the baby is born, and spirals out like a ribbon winding around a clock face. It’s dark blue whenever his daughter was sleeping and yellow whenever she was awake. In the first few days of her life, it’s an absolute mess (sorry to break it to you, soon-to-be-new mums and dads) but then slowly it settles down, and a pattern begins to emerge. A tiny human, synchronising to the rhythm of life, all told through a continuous line on a page.

Of course, with the advent of wearables, it’s become easier than ever to monitor our bodies and our health. Technology has empowered us in how we look after our wellbeing. AI-powered wearables connected to smartphone apps now enable us to track everything from sleep patterns and blood oxygen levels, to heart rate and blood pressure.

There is something comforting in knowing the numbers, in taking objective measurements of how we’re doing. This, of course, can be a great form of motivation towards our goal – especially socially – connecting with a community who are all concerned with the documentation and ownership of health. I know I’m not alone in being completely unable to make myself exercise without some form of external accountability, and for a lot of people the technology really helps on those days when you can’t seem to get off the couch.

However, we do need to be careful not to place the tracking of numbers above wellbeing, and how we feel. Lots of the things we’re told we need to track daily, such as eight glasses of water a day or 10,000 steps a day have almost no scientific evidence to support them. 10,000 steps in particular is a completely arbitrary number, based on a 60s Japanese pedometer called the Manpo-kei, which means “10,000 steps meter”. It was named that because the Japanese character for 10,000 looks like a person walking or running, which was then rolled out in the marketing campaign.

When it comes to fitness, remember that the numbers are always a placeholder for what we actually want to know. Everybody is different, and reacts in a different way to external forces. And while trackers allow people the sense of understanding what is “good” or “regular” within themselves, this data should only be used to inform your health, it shouldn’t override the actual human body.