Being overweight or seriously underweight as a teenager curbs life expectancy as much as smoking 10 cigarettes a day, a study suggests.
Swedish researchers followed 46,000 men from the age of 18 for 38 years.
Being obese or smoking more than 10 a day doubled the premature death risk, the British Medical Journal reported.
Being overweight, seriously underweight or smoking 10 or less raised it by 30% - and interestingly the fat non-smoker ran the same risk as the fat smoker.
Those who were underweight - with a Body Mass Index (BMI) of less than 18.5 - had no increased risk of dying early, regardless of whether they smoked or not. But the team from the Karolinska Institute in Sweden found that those who were seriously underweight - with a BMI of 17 or less - ran the same risk as those who were overweight. They looked at 45,920 men born between 1949 and 1951 who were military conscripts. In this period as few as 3% of Swedish men were exempt from military service.
http://news.bbc.co.uk/1/hi/health/7908575.stm