Being obese can take years off your life and in some cases may be as dangerous as smoking, a new study says. British researchers at the University of Oxford analyzed 57 studies mostly in Europe and North America, following nearly one million people for an average of 10 to 15 years. During that time, about 100,000 of those people died. The studies used Body Mass Index (BMI), a measurement that divides a person's weight in kilograms by their height squared in meters to determine obesity. Researchers found that death rates were lowest in people who had a BMI of 23 to 24, on the high side of the normal range.
Peto and colleagues found that people who were moderately fat, with a BMI from 30 to 35, lost about three years of life. People who were morbidly fat - those with a BMI above 40 - lost about 10 years off their expected lifespan, similar to the effect of lifelong smoking.