Most people who are overweight are not at a greater risk of dying early in comparison to their slimmer peers.
This is the conclusion of a study by researchers from the US, who explored the impact of a BMI on mortality in more than 550,000 US adults.
In the last quarter-century, overweight and obese BMIs have become more common — with an estimated 25.9 percent of adults in England being obese and 37.9 percent overweight.
It is well-established that having an elevated BMI can contribute to a number of cardio-metabolic conditions.
However, the team explained that previous studies into the association between BMI and all-cause mortality have offered inconsistent results.
The study was undertaken by public health expert Dr Aayush Visaria and pharmacoepidemiologist Dr Soko Setoguchi, both of New Jersey’s Rutgers University.
The duo said: “Our study highlights the increasing reservations of using BMI along to drive clinical decisions.
“There is no clear increase in all-cause mortality across a range of traditionally normal and overweight BMI ranges.
“However, that is not to say that morbidity [disease] is similar across these BMI ranges. Future studies will need to assess incidence of cardio-metabolic morbidities.”
In their investigation, the researchers analysed health, mortality and demographic data on 554,332 US adults that had been collected as part of the 1999–National Health Interview Survey and the 2019 US National Death Index.
The duo calculated each subject’s BMI from self-reported heights and weights, dividing the cohort into nine BMI categories.
The average subject in the study was 46 years old, 50 percent were female, and 69 percent were non-Hispanic White. The average effective follow-up period was 9 years, and the maximum 20 years.
Moreover, 35 percent of subjects had a BMI between 25 and 30 — that is, overweight — while 27.2 percent were classified as being obese.
Over the period covered by the study, the researchers observed that there were 75,807 deaths among the subjects.
They found that the risk of all-cause mortality was similar across a wide range of body mass indices — and, with older adults, there was no significant increase in death rates between BMIs of 22.5 and 34.9, which extends into the range typically considered obese.
For younger adults, meanwhile, there was no significant increase in mortality for any BMI between 22.5 and 27.4.
When considering all obese adults with a BMI of 30 or higher, however, the team found that there was a 21–108% increase in mortality risk attributable to their weight.
The patterns seen in the overall population, the team added, remained largely the same in men and women, and across different races and ethnicities.
The full findings of the study were published in the journal PLOS ONE.
