Now, a study published in the Lancet shows being overweight—not just obese—is associated with a higher risk of dying early of any cause. “The results highlight that even slight increase in BMI can cause harm,” says Dr. Emanuele Di Angelantonio, a lecturer at the University of Cambridge and lead author of the study. “There is a progression of increased risk beginning with being overweight and continuing through all levels of obesity.”
According to the report, people with BMI readings above the recommended range who were considered overweight showed an 11% 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%, and for those with the highest level of obesity, or BMI of 40 or more, the risk nearly tripled.
The researchers looked at data from nearly 4 million people from 32 countries who were part of the Global BMI Mortality Collaboration. They excluded smokers. The data were collected to better understand how BMI is related to mortality and whether there were global trends that emerged across different regions of the world. Di Angelantonio and his colleagues did indeed find some universal patterns.
The data also found differences between men and women, with the risk to men in general three times greater than for women when they are overweight or obese. The reasons for the gender difference isn’t clear, but other studies have pointed to differences in things like how men and women respond to insulin and variations in the amount of harmful fat in the liver that could be affected by obesity.
The results should put to rest confusion over whether overweight can lower risk of premature death, says Shilpa Bhupathiraju, one of the co-authors, from the Harvard T. H. Chan School of Public Health.
“Doctors should continue to counsel their patients about the effects of having any excess body weight,” says Bhupathiraju. “The fact that we see these strong associations across different regions of the world means we are pretty confident in these results.”