Are you truly healthy? A new wave of tests promises the ultimate check-up

I’M WELL, thank you. Or at least I think I am. I have no major illness to speak of, I am of average weight and a recent knee scan showed my joints are sufficiently well oiled. My blood pressure is spot on and I exercise fairly regularly – at least, some of the time. Then again, I have a cough I can’t shake. I don’t feel physically strong. And since I am turning 40, I should really get a mammogram, given my family history of breast cancer.

So, am I healthy? With my “big birthday” looming, I have increasingly found myself wondering about that – about what it is to be healthy and how we can best measure whether we are or not. I had assumed there would be some well-established way to find out. But when I began to investigate, I soon discovered that it is a surprisingly hard question to answer.

That is partly because we now know that many of the metrics we rely on, such as body mass index (BMI), are flawed. But it is also the result of fresh insights into the microbiome and the immune system, among other things. These are giving rise to a whole new raft of tests promising a better gauge of health – from those that probe your gut bacteria or your metabolites to those that provide you with an “immune grade”. So, which of these new tests, if any, should I be turning to for the ultimate health check?

What does it mean to be healthy?

Your common-sense definition of what it means to be healthy probably roughly aligns with…