Carrying extra weight may not always shorten your life.
New research from Denmark suggests that people who are overweight, and even some with obesity, do not necessarily face a higher risk of early death compared with those in the so-called healthy weight range.
The findings were presented at the European Association for the Study of Diabetes (EASD) meeting in Vienna and challenge long-held assumptions about body mass index (BMI) and health.
The study followed more than 85,000 adults, most of them women in their mid-60s, for around five years.
During that period, about 7,500 participants died. When the researchers compared BMI with the likelihood of death, they noticed striking patterns. Those who were underweight had the highest risk.
In fact, being underweight nearly tripled the chances of dying compared with people whose BMI sat at the top of the normal range, between 22.5 and 25.
Even individuals who were technically in the healthy range but at the lower end, with a BMI of 18.5 to 20, were twice as likely to die as those at the upper end.
People with a BMI of 20 to 22.5 were also more likely to die than the reference group.
What surprised the researchers most was that people in the overweight category, with a BMI of 25 to 30, did not have an increased risk of death.
The same was true for those in the lower range of obesity, between 30 and 35. Only when BMI reached 35 or higher did the risk start to rise. People with severe obesity, defined as a BMI over 40, were more than twice as likely to die, while those in the 35 to 40 range faced about a 23 percent higher risk.
These findings raise the question of why a higher BMI might not always translate into worse health outcomes.
One explanation is reverse causation. Some people lose weight because of illness, and it is the illness rather than the low weight itself that increases their risk of death. Another possibility is that older adults who carry extra weight but still live long lives may have protective factors that help them stay healthier despite their size.
The study also highlights the limits of BMI as a single measure of health. Fat distribution plays a critical role. Fat that builds up deep in the abdomen around vital organs, known as visceral fat, can cause serious metabolic problems, including type 2 diabetes and high blood pressure.
By contrast, fat stored in the hips, thighs or buttocks is less harmful. This means two people with the same BMI may face very different health risks, depending on where their body stores fat.
The researchers stress that their findings should not be taken as a reason to ignore the dangers of obesity.
Excess weight can still raise the risk of diabetes, heart disease and several types of cancer. But the results suggest that being slightly overweight is not automatically dangerous, particularly in older adults.
In fact, being underweight may carry far greater risks than carrying a few extra kilos.
