Smoking and obesity are risk factors for untimely death, but a new study suggests they can do even more harm together than independently. In an analysis of more than 237,000 AARP members between the ages of 50 and 71, researchers found that smokers with a body mass index (BMI) of greater than or equal to 35 had a 6 to 8 times greater risk of dying than normal-weight people who had never smoked. Current smokers with large waistlines (about 42 inches for men and 38 inches for women) also had more than 5 times the risk of dying as small-waisted (about 37 inches for men and 32 inches for women) people who had never smoked--regardless of BMI. Very thin smokers (with a BMI under 18.5) had a greater risk of dying than their normal-weight peers. When the factors were compared independently, quitting smoking provided a greater reduction in risk than did losing weight.
Source: American Journal of Clinical Nutrition, November 2008