New Year’s Eve is a magical time. The old is about to end, the new is just on the cusp of beginning, and in this wonderful transition space we make promises about our lives ahead. Promises to lose weight, promises to study harder, promises to take up a gym membership and finally get fit.

We make a resolution to change our lives for the better.

And then, almost invariably, we fail. Partly because it is hard to make such massive changes in your life, but also partly because the world is bigger than a single person, and society has a lot more of a say in our lives than we care to admit.

It’s a sad truth that New Year’s resolutions are extremely unlikely to succeed. There hasn’t been an enormous amount of research on the subject, but what’s out there shows that people usually fail in their resolutions between two weeks and a month after making them. There’s no evidence that they actually help with things like weight loss, which is not particularly surprising when so few manage to keep them up longer than a fortnight.

And yet, each year, millions of us make them. Promising to change like a politician desperate to turn the tide before the next election. But, like politicians, the unfortunate reality is our promises are bigger than ourselves. The environment just does not allow for us to keep to all of the resolutions we make.

Get fit: be rich

One of the key ideas in public health is the concept of social determinants of health. These are the economic and social conditions that can make people healthy or sick – things outside of individual control that determine how healthily we live our lives. An example from some of my colleagues’ work is that you are less likely to have diabetes if you live in a wealthier suburb, were born in the same country that you live, and were healthier to start off with – you didn’t have other diseases already.

The truth is social determinants control far more of our lives than we would like to admit. While a common refrain from politicians who would like to cut services is that each individual determines their own fate, the reality is that things as diverse as whether one of your parents went to prison or whether you grew up near a motorway can define your health for the rest of your life.

Born wealthy and privileged? Chances are you’ll find it much easier to improve your health. Born to serious disadvantage? It’s not impossible, but it becomes that much harder to do.

This doesn’t mean that it’s impossible to improve your health at an individual level, but it’s quite easy to see how it might be easier to lose weight if your local eatery serves wraps and salads rather than fish and chips.

Which brings us back to New Year’s resolutions. If your environment promotes good health, then it’s much easier to keep your resolution to be healthier. If not, it’s probably going to be far, far harder.

What can we do?

The problem of social determinants is not a new one – the seminal work in this field was being done more than half a century ago. As with many other complex problems, there are no simple, easy fixes.

But that doesn’t mean there isn’t anything we can do.

Ultimately, social determinants are about inequality. When some people are more able to access important services – whether that be schools or hospitals or anything else – simply because of an accident of their birth, it creates a gulf between the haves and the have-nots.

Often improving the situation means tackling the underlying inequalities that have caused it.

Sometimes this means developing targeted services that help the most vulnerable. Sometimes it means taking public funds and improving the living conditions of people in need. Sometimes, it just means giving people money so they can use it to improve their lives.

These are all well-evidenced interventions for improving health, but politically difficult. They require us all to pay more tax to protect the vulnerable, which is never a popular platform.

So what can we do? Well, maybe this year, when you’re pouring a glass of champagne instead of promising to change your life, make a commitment to improving everyone else’s. Resolutions might not be very effective, but if we all promise to change society, even by just a little bit, who knows?

Maybe in 2019 we can all be a little bit better off.

Happy New Year.