Being overweight or underweight can diminish your life expectancy by four years, a large UK study suggests.
Results were published in the Lancet Diabetes and Endocrinology.
The report showed that life expectancy for obese men and women was 4.2 and 3.5 years shorter respectively than people in the entire healthy BMI weight range.
The difference for underweight men and women was 4.3 (men) and 4.5 (women) years.
Researchers found that, from the age of 40, people at the higher end of the healthy Body Mass Index (BMI) range had the lowest risk of dying from disease.
The report involved nearly 2 million people who were registered with doctors in the UK.
BMI is calculated by dividing an adult's weight by the square of their height.
A "healthy" BMI score ranges from 18.5 to 25.
Not everybody in the healthy category is at the lowest risk of disease, according to report author Dr Krishnan Bhaskaran.
For most causes of death we found that there was an 'optimal' BMI level, with risk of death increasing both below and above that level”, he commented to BBC.