The study of 3.9 million adults culled data from 189 studies; participants were non-smokers who had no known chronic disease and lived at least 5 years to be included in the analysis.
Being overweight or obese is linked to dying before age 70–especially for men, according to a worldwide study of 3.9 million adults published today in Lancet.1
The analysis pulled data from adults in 189 studies across 4 continents, and found that risk of early death rises along with weight, along with greater likelihood of coronary artery disease, stroke, respiratory disease, and cancer. Among those who are overweight, the risk of dying early is 3 times higher for men than women.
Obesity is on the rise in the United States and around the world, with the World Health Organization estimating that 1.3 billion adults are at least overweight, making it second only to smoking as a culprit in early death, according to a study co-author.
“Smoking causes about a quarter of all premature deaths in Europe and North America, and smokers can halve their risk of premature death by stopping,” said Sir Richard Peto, of the University of Oxford, in a statement released with the study. “But overweight and obesity now cause about 1 in 7 of all premature deaths in Europe and 1 in 5 of all premature deaths in North America.”
CDC and other health agencies use body mass index (BMI) to gauge whether one is overweight, even though this analysis recognizes its limitations. BMI may overlook factors such as being muscular or having high excess fat on a thin frame. Persons of Asian heritage, for example, can be considered overweight with a BMI of 23, due to differences in body composition. For this study, a person with a BMI of 20 to 25 was normal weight; a BMI of 25 to 29.9 was considered overweight, and 30 or higher was considered obese.
All participants in the meta-analysis were 20 to 90 years old and non-smokers at the start. They were not known to have chronic disease at the time their BMI was recorded. The new analysis involves participants who lived at least 5 years; of the 3,951,455 participants, including 69% women, 385,879 died. Median follow-up was 13.7 years.
A breakdown of the data shows that the best life expectancy occurred for those with a BMI of 20 to 22.5; this group fared slightly better than those with a BMI of 22.5 to 25. Risk went up slightly for those with BMI of 25 to 27.5, with a hazard ratio (HR) of 1.07 relative to those at normal BMI. After a BMI of 27.5, risk starts to elevate, with those from 27.5 to 30 seeing an HR of 1.20, followed by 1.45 for those with BMI 30 to 35, 1.94 for those with BMI 35 to 40, and a whopping 2.67 for those with BMI above 40.
Those underweight, with a BMI of 15 to 18.5, had an elevated risk of early death as well, with an HR of 1.51.
“Overweight people lose about a year of life expectancy, and moderately obese people (BMI 30 to 35) lose about 3 years of life expectancy,” said the study’s lead author, Emanuele Di Angelantoni, PhD, of the University of Cambridge.
Researchers concluded that the relationship between a higher BMI and increased mortality was “strong and positive in every global region we studied, except for south Asia, where numbers of deaths were small.” They concluded that strategies are needed “to combat the entire spectrum of excess adiposity worldwide.”
In an accompanying commentary, David Berrigan, PhD, MPH; Richard P. Troiano, PhD; and Barry I. Graubard, PhD, of the National Cancer Institute ask whether the analysis, with its many exclusions, can be “generalizable and unbiased.” With randomized trials in this realm problematic, big data sets are what researchers have, they said. The challenge is translating epidemiological evidence into public policy, which is enormously difficult.
Multiple strategies have been offered to fight obesity, including limits on marketing junk food to children and soda taxes to curb consumption of empty calories. A separate report released today in the United States by the National Institutes of Health finds that amid several points of good news for children’s health, obesity rates stubbornly climb.2
While unchanged in recent years, the NIH report found that are still rising long term; 19% of children age 6 to 17 years were obese from 2011-2014. Children of Hispanic origin had the highest obesity rates and were least likely to have insurance coverage during the study period, with 10% uninsured.
1.Â Â Â Â Â The Global BMI Mortality Collaboration. Body mass index and all-cause mortality: individual participant data meta-analysis of 239 prospective studies in 4 continents [published online July 13, 2016]. Lancet. 2016; http://dx.doi.org/10.1016/ S0140-6736(16)30175-1.
2.Â Â Â Â Â America’s Children in Brief: key national indicators of well-being, 2016. National Institutes of Health website. http://www.childstats.gov/americaschildren/index.asp. Published July 12, 2016. Accessed July 13, 2016.