Fat but fit - what latest research on BMI reveals

Being slightly overweight might not shorten your life, but being very thin might, writes Rachel Woods, senior lecturer in physiology at the University of Lincoln.

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A large Danish study tracking more than 85,000 adults has found that people with a BMI below 18.5 were nearly three times more likely to die early than those in the middle to upper end of the so-called 'healthy' range.

The link between body weight and health is more complicated than often assumed. This new research, which is yet to be peer reviewed, suggests that the lowest risk of death may not sit neatly in the traditional 'healthy' body mass index (BMI) range.

Instead, the findings suggest that people with BMIs that would normally be classed as 'overweight' appear to have outcomes that are just as good as, or even better than, those with lower BMIs.

Researchers found a U-shaped curve when plotting BMI against mortality, meaning those with the lowest and highest BMIs were at the highest risk of death.