Obesity increases risk of an early death to the same extent as smoking ten or more cigarettes a day.

Obesity increases risk of an early death by the same extent as smoking ten or more cigarettes a day.

As a nation, we’re getting fatter. You’ve probably heard people speak about an ‘obesity epidemic’ sweeping the country, and worryingly, about a quarter of adults are now obese. And a new study published this week in the British Medical Journal shows that being obese could be just as risky to our health as being a smoker.

The study

The study looked at nearly 50,000 young men aged 16-19 and followed them up for 38 years, to see the impact of weight and smoking on how long they lived for.

In Sweden, where the study took place, military national service used to be compulsory and all older male teenagers had to participate. When they entered the programme, they answered questions about their lifestyle and had their weight and height measured.

The researchers collected all this data and used it to compare the recruits’ risk of an early death to their weight and smoking habits. They adjusted all their results for the men’s age, social background, and muscle strength (as a general indicator of their fitness).

What they found

The scientists found that being overweight as a teenager (with a BMI between 25 and 30) increased the risk of an early death by the same extent as smoking one to ten cigarettes a day.

And being obese (with a BMI over 30) was just as dangerous as smoking more than ten cigarettes a day. Either one doubled the risk of an early death.

The effects of smoking and obesity also piled on top of each other. People who were obese and smoked more than ten cigarettes a day were five times more likely to die early than non-smokers with a healthy bodyweight.

What we know

In some ways, the results aren’t that surprising.

It’s well known that smoking causes a host of health problems. It not only increases the risk of lung cancer, but about a dozen other types as well including cancers of the mouth, larynx (voice box), oesophagus (food pipe), liver, pancreas, stomach, kidney, bladder and cervix, as well as some types of leukaemia. We also know that smoking causes heart disease and chronic lung problems.

All in all, smokers lose about ten years of life compared to non-smokers.

We also already know that being overweight or obese increases your risk of a number of different types of cancer, including cancers of the:

  • breast in women after the menopause
  • bowel
  • womb
  • oesophagus (food pipe)
  • pancreas
  • kidney
  • gallbladder.

Obesity also increases the risk of heart disease and type 2 diabetes. In fact, that’s why we have teamed up with the British Heart Foundation and Diabetes UK on our latest advertising campaign, as part of the Change4Life programme.

It’s been estimated that being overweight or obese causes about 13,000 cases of cancer each year. So it’s easy to see why piling on the pounds increases the risk of dying prematurely. But this study suggests that these risks are comparable to those of smoking. That’s important, for while the number of smokers in the UK has fallen, levels of obesity are steadily rising

And a recent survey showed that two in three parents didn’t know that being overweight in childhood could lead to a higher risk of cancer later in life. So there’s still a long way to go before everyone understands how their weight affects their cancer risk.

What you can do

Cancer Research UK, in partnership with Weight Concern, have developed Ten Top Tips for a healthy weight. The tips are designed to fit into your daily life and are based on the best available scientific evidence.

You can get started with the Tips by downloading or ordering the Ten Top Tips leaflet, as well as a wallet-sized shopping card to help you understand food labels.

To get help stopping smoking, you can call the NHS stop smoking helpline on 0800 169 0 169, visit http://smokefree.nhs.uk/, or call QuitLine on 0800 00 22 00.


M. Neovius, J. Sundstrom, F. Rasmussen (2009). Combined effects of overweight and smoking in late adolescence on subsequent mortality: nationwide cohort study BMJ, 338 (feb24 2) DOI: 10.1136/bmj.b496


Jessica Harris is a guest-blogger working in Cancer Research UK’s Health Information Department.