Danish study challenges link between obesity and early death
Being overweight does not necessarily increase the risk of an early death, new research suggests.
The findings, presented at the annual meeting of the European Association for the Study of Diabetes (EASD) in Vienna, indicate that it may be possible to be “fat but fit.”
Researchers in Denmark examined the health records of more than 85,000 people and found that those with a body mass index (BMI) in the overweight category, and even some with obesity, were no more likely to die within five years of follow-up than those with a BMI in the upper end of the so-called healthy range (22.5–25.0 kg/m²).
Surprisingly, people with a BMI in the middle and lower parts of the normal weight range (18.5–22.5 kg/m²) were more likely to die than those at the higher end. Individuals classified as underweight faced the greatest risk.
“Both underweight and obesity are major global health challenges,” said Dr Sigrid Bjerge Gribsholt, of the Steno Diabetes Center Aarhus at Aarhus University Hospital, who led the research.
She explained that obesity can disrupt metabolism, weaken immunity and contribute to conditions such as type 2 diabetes, cardiovascular disease and as many as 15 types of cancer. Underweight, meanwhile, is often linked to malnutrition and nutrient deficiencies.
The study analysed health data from 85,761 participants, most of them women with a median age of 66. Over the follow-up period, 7,555 individuals, which is around eight per cent, died.
The results showed that people in the underweight category were almost three times more likely to die than those in the reference group. Severe obesity (BMI over 40 kg/m²) was associated with more than double the risk.
However, being overweight (BMI 25–30 kg/m²) or moderately obese (BMI 30–35 kg/m²) did not carry a higher risk of death. Even those with a BMI of 35–40 kg/m² had only a slightly increased risk, 23 per cent higher than the reference population.
Researchers noted that lower mortality risk in heavier groups may partly be explained by “reverse causation”: some people may lose weight due to underlying illness, which increases their risk of death.
Professor Jens Meldgaard Bruun, also of the Steno Diabetes Center Aarhus, stressed that BMI is not the only factor to consider. “Where fat is stored in the body makes a huge difference. Visceral fat, deep within the abdomen, is far more harmful than fat on the hips or thighs,” he said.
The researchers concluded that obesity treatment should be personalised, taking into account fat distribution and conditions such as type 2 diabetes, rather than focusing solely on BMI.