Both low and high Body Mass Indices (BMI) were associated with an increased risk of death from various causes, according to a new study recently released by the London School of Hygiene and Tropical Medicine (LSHTM).
The study, led by LSHTM researchers, looks at how BMI is associated with the risk of death in general, and from a full spectrum of different causes. A total of 3.6 million people and 367,512 deaths were included in the analysis.
BMI is a value derived from an individual's weight and height.
The team suggests that a BMI of between 21 and 25 kilograms per square meter was associated with the lowest risk of dying from cancer and heart diseases. Overall, both low and high BMI were associated with an increased risk of death.
Obesity (BMI of 30 or more) was associated with a loss of 4.2 years of life in men and 3.5 years in women with excess weight associated with a higher risk of death from cancer and heart diseases, as well as deaths in other major categories including respiratory diseases, liver disease, and diabetes.
Low body weight was also associated with a higher risk of death from a wide range of causes including cardiovascular disease, respiratory disease, dementia and Alzheimer's and suicide.
"We found important associations between BMI and most causes of death examined, highlighting that body weight relative to height is linked to risk of a very wide range of conditions," said lead author and associate professor in statistical epidemiology at LSHTM, Krishnan Bhaskaran.
The study has been published in the journal The Lancet Diabetes and Endocrinology.
However, the authors also acknowledge limitations of the study including that there was no information available on the diet or physical activity levels of people included in the study so it was not possible to look at the interplay between BMI and these related factors.