For this study, researchers analyzed data from 189 studies involving almost 4 million people who were nonsmokers, were 20 to 90 years old and had no chronic diseases. Over a span of about 14 years, 385,879 of the participants died. Based on their body mass index (BMI), those who were overweight or obese were more likely than normal-weight people to have died prematurely — that is, before age 70 — with a steep and steady increase in risk as BMI increased
The effect was more than evident for people who were overweight and for those who were obese. the chance of dying prematurely was three times greater for men who were obese than for obese women.
Researchers suggest that if those obese people had normal BMI at least 1 out of 5 premature deaths could be prevented in North America.
Who Is Affected
People who are overweight or obese. The higher someone’s BMI — which is an estimate of body fat calculated from the person’s height and weight — the greater the chance of developing medical problems. A normal BMI is 18.5 to 24.9; overweight starts at 25 and obesity at 30. Today, 70 percent of adults in the United States are considered overweight or obese.
The analysis did not explain why the death rate was so much greater for men. Only BMI was used to measure obesity; fat distribution on the body, such as waist size, which is known to have an effect on health, was not considered.
You can find the study here
You can also calculate your BMI by clicking here