Julian Baggini: Confused about health? Drink more

Hoping to create a healthier you this new year? If so, I've got some good news and some bad news. But above all, I have news. Plenty of it. Too much, as usual. And what you find is always changing, often contradictory and rarely encouraging.

So today, on Radio 4's You and Yours, we'll be hearing how some doctors are suggesting that official safe limits for alcohol have been plucked out of the air and that we should all be drinking much less than the advised 21-28 units for men and 14-21 for women. This follows a World Cancer Research Fund warning that on average we consume 200 nutritionally empty calories a day from booze. At the same time, as Jeremy Laurance reported in this paper yesterday, a huge survey of 100 epidemiological studies from around the world, covering three million people, suggests we shouldn't worry as much about that excess. It seems that the mildly obese, with a Body Mass Index (BMI) of between 30 and 34.9, if anything actually tend to live longer than the slim and the very obese. Confused? Join the 52 per cent of Americans who think that working out their income taxes is easier than knowing what they should and shouldn't eat to be healthier.

The problem, however, is not with the research, but in how it is used. The comparison with tax returns is very apt: we seem to have bought into a computational, ledger-based model of health which breaks everything down into its constituent parts and counts what goes in and out.

Look at the reports I've highlighted and the key concepts are "BMI", "calories" and "units of alcohol", all things that can be measured and then used to create rulers with which to measure us.

Our bodies, however, are more complicated than that. They are systems in which all the different elements work together. As soon as you try to isolate one, you lose the bigger picture and can easily be led astray. For instance, what increases one health risk may reduce another. So even if it is a firm fact that moderate alcohol intake increases the risk of some cancers, it doesn't automatically follow that you should drink less. If it has other health benefits, it could be that on balance it is better to drink a little than be teetotal. Research rarely backs a specific lifestyle change because findings are usually a matter of "all other things being equal", which they normally aren't.

However, thinking of ourselves as complex systems is hard and so we leap upon simple, officially sanctioned numbers to live by. It's not enough to know that we need to eat plenty of fruit and veg; we have to know it's five a day.

We learned a long time ago how targets can be counterproductive in corporate contexts, with schools teaching to the test to the detriment of a rounded education and hospitals following perverse incentives which do not lead to the best overall health outcomes. We seem to be taking longer to realise that what is true socially and politically is also true personally.

Data-based quantitative research is important, but what is well-designed for the lab is ill suited to living life outside it. Translating best evidence into best practice requires moving from science to a kind of art, where atomistic measurement needs to give way to informed, holistic judgement.

In short, we should count less and think more.