It's simple, really: Being too heavy can cost you your life. The biggest ever analysis of data on obesity clearly states that overweight people could lose their life one year earlier than previously expected and moderately obese people can die up to three years earlier.

The study starkly debunks the so-called “obesity paradox,” which had suggested a possible survival advantage to being overweight.

In North America and Europe, obesity is the number two cause of premature death behind smoking. In fact, overweight and obesity now cause about one in seven of all premature deaths in Europe and one in five of all premature deaths in North America.

In the new study, which the authors say is the largest-ever such analysis, researchers pored over data for nearly 4 million adults in 32 countries published from 1970 to 2015. They compared the risk of death to people's body mass index, or BMI, a measure of body fat that is calculated using height and weight.

The researchers excluded current or former smokers, those with chronic diseases at the beginning of the study, and any who died in the first five years of follow-up. This left 4 million adults to analyze. The study has been published in The Lancet.

The data comes down hard on men. The risk of premature death is around three times more for a man than for a woman. Men are at risk of an earlier death under the best of circumstances, but the data shows that obesity worsens the risk. The research alsofound that the hazards of excess body weight were greater in younger than in older people.

Here's how obesity kills us: For each 5-unit increase in BMI above 25 kg/m2, the corresponding increases in risk were 49 percent for cardiovascular mortality, 38 percent for respiratory disease mortality, and 19 percent for cancer mortality.

People with BMI readings above the recommended range who were considered overweight showed an 11 percent increased risk of dying early, defined as death before age 70, compared to people who maintained their recommended BMI. For people with BMI between 30 and 35, the first category for obesity, the risk of premature death increased to 45 percent, and for those with the highest level of obesity, or BMI of 40 or more, the risk nearly tripled.

The authors of the report say that assuming that the associations between high BMI and mortality are largely causal. That is, if those who were overweight or obese had normal levels of BMI, then one in 7 premature deaths in Europe and one in 5 in North America would be avoided.