It also found that those who are overweight have the same risk as less heavy smokers.
The authors, led by Dr Martin Neovius at Karolinska Institute in Stockholm, Sweden, analysed the cause of death of over 45,000 men who underwent mandatory military conscription tests in Sweden.
The participants all had their BMI measured and reported their smoking status at the age of 18 and were followed up for an average of 38 years.
Early death was linked to the number of cigarettes smoked per day.
When the effects of weight and smoking were combined, the researchers found no significant change in the results. The combination of obesity and heavy smoking was associated with a large excess risk of early death (almost five times greater than normal weight non-smokers), according to BMJ Online.
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