New Study Finds Obesity is Second Leading Cause of Premature Death

In what has been called “possibly one of the largest” studies of body mass index (BMI) and mortality, researchers are reporting that obesity is now second to smoking as the leading cause of premature death in Europe and North America. The study was published on July 13 in the UK medical journal The Lancet.

Based on data from nearly four million individuals who participated in 189 different studies, researchers found that those with a BMI greater than 25 kg/m2 had a significantly higher risk of mortality from all causes of death. They estimate 1 in 6 premature deaths are potentially avoidable with weight loss.

The increased risk is seen particularly in men and is consistent in Europe, North America, East Asia, Australia, and New Zealand.

According to Sir Richard Peto, the study’s co-author and a professor of medical statistics and epidemiology at the University of Oxford, “Smoking causes about a quarter of all premature deaths in Europe and in North America, and smokers can halve their risk of premature death by stopping. But 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."

Peto and lead author Emanuele Di Angelantonio, MD, PhD from University of Cambridge hope their research will finally "put to rest" any arguments about the association between BMI and obesity.

In an interview with Medscape Medical News, Di Angelantonio said, "Of course, there's a lot of research that needs to be done in trying to understand other factors implicated with obesity, especially, for example, fat distribution and visceral fat, which we haven't been able to study in this paper."

The new study contradicts the findings of a 2013 study published by Katherine M. Flegal, PhD et al that suggested that Grade 1 obesity overall “was not associated with higher mortality, and overweight was associated with significantly lower all-cause mortality” (JAMA. 2013;309: 71-82).

Di Angelantonio attributes the difference in the findings of the two studies to the “much stricter methodology” adopted by him and his colleagues as well as the much larger data set.

He noted that the previous study sent the risky message that "being overweight and slightly obese is normal."

"Actually, it's not," he argues. "I think here we are reinforcing this message, and we are reinforcing the need to have public-health measures to try to implement a strategy to reduce body weight."

The study’s authors established the Global BMI Mortality Collaboration, which included 500 investigators from 300 institutions in 32 countries, in order to develop a standardized method for comparing the associations between BMI and mortality.   

Once the collaboration agreed on the plan of analysis they searched MedLine, Embase and Scopus databases for studies. They narrowed their analysis to a group of 3,951,455 participants from 189 studies. The participants were individuals aged 20 to 90 years old who had never smoked and had a BMI ranging from 15 kg/m2 to 60 kg/m2. None reported any chronic diseases when they were recruited for their study and were still being followed up 5 years later. Of that group, 385,879 individuals died.

The study found that the proportion of premature deaths that could be avoided if the overweight and obese individuals returned to a normal BMI would be 1 in 5 in the United States, 1 in 6 in Australia and New Zealand, 1 in 7 in Europehttp://www.medscape.com/viewarticle/866096#vp_1, and 1 in 20 in East Asia.

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