Being underweight appears to be associated with a greater risk of early death than being mildly overweight, with factors like fat distribution and existing health conditions influencing outcomes beyond BMI
A large Danish study tracking over 85,000 adults has found that being underweight carries a substantially higher risk of early death compared with being mildly overweight, challenging standard assumptions about body mass index (BMI) and health.
Participants in the underweight category were nearly three times more likely to die during the study period than those in the upper-normal BMI range. Meanwhile, people who were overweight or moderately obese did not show higher mortality than those at the upper end of “normal” BMI.
Researchers emphasised that health isn’t just about weight: “Body fat distribution and underlying health conditions play a big role in overall health.” They noted that visceral fat—fat stored deep in the abdomen—may impair metabolic health, whereas fat stored elsewhere like hips or thighs may be less harmful.
Some experts caution that residual illness might confound results: “Diseases like cancer or heart failure cause weight loss first, which makes low weight seem more dangerous than it actually is.” The study calls into question BMI-alone health guidance and suggests incorporating factors such as waist-to-height ratio, muscle mass, biomarkers, sex and ethnicity.