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Larry Smarr: The world's most self-measured man

Larry Smarr. Photo/UC San Diego/Supplied

A US computer scientist who has been monitoring the state of his health for nearly two decades says he’s healthier now than he’s been in 15 years.

Larry Smarr has been called perhaps the world’s most self-measured man. Never mind your average Fitbit – although he wears one of those as well – Smarr’s digital database of his own biomarkers runs to hundreds of figures.

For the professor of computer science and engineering at the University of California, San Diego, basics such as heart rate, blood pressure, steps taken, weight and hours of sleep were just the beginning. Since he began collecting his data nearly 20 years ago, the measurements have become more intense and more invasive, but “we’re still just scratching the surface of what measuring your body is going to be like”.

Data from his blood and stool samples provided the information that led to a diagnosis of Crohn’s disease in 2012, when he was pre-symptomatic. He collects stool and blood samples every month, but for two-week stretches also wears a fine needle embedded in his arm attached to a microprocessor, which records his blood-glucose levels every 15 minutes as he experiments with different eating and fasting regimes. He discovered not only that he was pre-diabetic, but also that time-restricted eating – eating only within a time frame of eight hours a day – dramatically improved his blood-sugar control.

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“A lot of people don’t think they’re pre-diabetic because they’re fit,” says Smarr. Indeed, it’s hard to imagine many are much fitter at the same age than Smarr, who has a resting heart rate of 40 beats a minute – normally seen only in professional athletes – is a healthy weight (86kg and 1.86m), exercises regularly and has a (medication-controlled) blood pressure of 135/70. Although chronologically he’s 70 years old, biologically, he’s still in his early sixties. He measures everything about himself because “you’re hallucinating if you think you can intuit what the measurement of a particular biomarker in your body is by your symptoms or how you feel”.

Smarr finds his Fitbit useful for monitoring the quality of his sleep, but he’s recently added a newer gadget, an Oura ring, which records heart-rate variability during sleep. “It’s helped me realise when I’m damaging myself by not getting enough sleep or eating and drinking alcohol too close to when I go to bed.”

Digesting a big meal can increase heart rate temporarily. “Your heart rate gradually decreases overnight, but if it starts pretty low rather than being high and coming down, you get a more restful sleep. You should finish eating and drinking three hours or more before going to sleep, so your digestive system has done most of its initial work. Most people suffer sleep deprivation and they don’t appreciate that means all kinds of systems in their body are not performing at peak. It’s nice if you can do 10,000 steps a day, but it doesn’t have as much benefit as eight hours of restful sleep a night.”

Smarr has close to 100 different biomarkers from his blood and stool samples that provide his personal average over time – a more valuable measurement than population-based comparisons. His various devices measure his blood pressure 100 times a month, his heart rate once a minute, his sleep every 15 minutes every night. He freezes stool samples once every fortnight. His genome has been mapped three times. This year, he plans to start measuring his blood for toxin exposure. The real insight, he says, will come from examining changes to personal baselines, which may be the first indicators of disease.

But what about the risk of overdiagnosis and overtreatment, which, according to US American academic physician H Gilbert Welch – interviewed by the Listener in 2015 – is the scourge of modern medicine. In a story about Smarr in the Atlantic in 2012, Welch, author of Overdiagnosed: Making People Sick in the Pursuit of Health, warned those who monitor themselves as closely as Smarr are pretty much guaranteed to find something “wrong”. Abnormality, he says, is normal, and constant monitoring can lead to unnecessary interventions.

Smarr concedes that, given enough data, you can find a problem, but says that’s not a bad thing. “You could argue we overmedicate our cars because we have things in there that measure the spark plugs, the fuel injection, the braking and 100 different variables. When you take your car in for maintenance, they read those things out and determine if any of them aren’t normal. It’s called preventive maintenance. When I grew up, you took your car in if you saw smoke coming out from under the hood. You want to catch those things early.”

He believes evidence that fitness trackers improve health outcomes will come with time. The technology is only about a decade old and population-based statistics are increasing by the year. In 2018, for example, Fitbit sold 14 million devices worldwide, up from 60,000 in 2010. “More and more data about your body is in your hands; it’s not in your doctor’s hands,” says Smarr. “We are very early in the transition from data-poor knowledge of yourself to data-rich knowledge. I’m healthier than I’ve been in 15 years. I’m less concerned about how long I live, than that I live as healthy as possible until I stop living.”

The information doesn’t stress him. “Stress comes from being in a situation that you feel you don’t have any control over. I have much greater knowledge and therefore control over my health. If you were driving a car on a busy highway at 70 miles an hour and could see out the windows and mirrors and see your speedometer … now put a black cloth across the windshield and over your instruments. Which situation is likely to cause you greater stress?”

This article was first published in the June 8, 2019 issue of the New Zealand Listener.