There’s no shortage of online chatter about longevity and how to live longer. Cold plunges, supplements, wearables, red light therapy. The longevity list is almost endless. It continues to grow exponentially. But the most powerful things you can do to extend your life and stay sharp into old age are the same things we’ve known about for decades. And the evidence for them continues to grow.

A 2017 study from the US followed nearly 15,000 people over 12 years to answer one simple question. What’s the impact of your everyday behaviour, such as smoking, weight, and alcohol intake, on how long you live and how many of those years you’ll spend free of disability? The results are clear. Your habits in midlife don’t merely shape how long you live. They shape how well you live.

The people who lived the longest and had the healthiest later years shared three traits. They had never smoked. They weren’t obese. And they drank alcohol in moderation. In fact, men and women with all three low-risk behaviours lived, on average, seven years longer than the rest of the population. Yet it’s not just about adding years. It’s about adding good years. Most of that extra time was spent without disability, walking, dressing, eating and living independently.

On the flip side, people who had smoked, were obese, and drank heavily lived shorter lives. They also spent more of those years with disability. Perhaps, no surprises there, but it’s a stark reminder. Your body keeps the score.

Obesity was the strongest predictor of early disability. Obese men lost three good years. Obese women lost six. That’s six more years struggling with everyday tasks such as getting out of bed, walking down the street, or dressing. While smoking shortened life more overall, obesity hit quality of life harder.

The reality is that more than a quarter of the people in this longevity study were obese. And while smoking rates have dropped, obesity is rising. That trend could wipe out a lot of the gains we’ve made in public health. This is why anti-obesity medications are such an exciting overall health development. 

It is also worth noting that lean beef tends to be higher in cholesterol-lowering fats (monounsaturated and polyunsaturated) than cholesterol-raising saturated fats. Many of the included trials also tried to match saturated fat across diets. This makes it unlikely that saturated fat was a major driver.

Moderate drinkers, fewer than 14 drinks per week for men, fewer than 7 for women, did better than both teetotallers and heavy drinkers. This is possibly because moderate drinkers tend to have other positive lifestyle traits. Or perhaps some benefit comes from social connection. But the takeaway is simple. Drinking a little is fine. Drinking too much, or hardly at all, can carry risks.

One of the most encouraging findings was about ex-smokers. People who had quit more than a decade ago and ticked the other healthy boxes (not obese, moderate drinkers) still gained nearly as much life as those who had never smoked at all. So if you’ve smoked in the past, all is not lost. You can still turn things around.

While this was a US longevity study, the implications are just as relevant here. The NHS is under strain. We have an ageing population. And too many people are spending their final years in poor health. But here’s the good news. These aren’t mysterious or unattainable changes. These are behaviours within our control.

The best-case scenario is that you live longer than average. You stay mobile, independent, and sharp into your 80s and beyond. And you spend fewer years dealing with the burden of disease. That’s good for you. It’s good for your family. And it’s good for the healthcare system.

Forget the biohacking gimmicks. The single best investment you can make for your longevity is to build a life where you eat well, move often, don’t smoke, and keep alcohol in check. These behaviours don’t just prevent illness. They preserve function. They keep you active, independent, and engaged with life for longer.

The best time to make a change is in your 30s or 40s. The second-best time is today.