United Kingdom (beritajatim.com) People who are overweight or underweight may reduce their life expectancy by about four years, according to a study published in the Lancet.
One of the UK's largest reports involved nearly two million people registered in clinics across the UK.
Researchers found that from the age of 40, people who had a body mass index (BMI) between 18 and 25 years had the lowest risk of dying from the disease.
But those with the highest index and the lowest BMI run lower life expectancy. BMI is calculated by comparing body weight in kilograms to the square of height in meters, and the number of "healthy" BMIs is between 18.5 and 25.
Most doctors say that this method is the best way to measure whether someone is overweight or not.
Cancer due to obesity in women
The study, published in the journal Lancet Diabetes and Endocrinology, showed life expectancies of overweight men and women 4.2 to 3.5 years lower than those who entered the healthy BMI index.
For men and women whose weight is less than normal, 4.3 and 4.5 years are smaller.
BMI is associated with several causes of death, including cancer, heart problems and respiratory diseases.
The study, with data analysis of 3.6 million people and 167,512 deaths, showed obesity or a BMI of over 30, associated with the possibility of two causes of death, heart disease and cancer.
"A BMI greater than 25, the main point of a healthy index, is associated with most cancers, heart, respiratory, liver and kidney diseases," said report author Dr. Krishnan Bhaskaran.
The British Journal of Cancer reported last April that obesity was associated with 7.5% of female cancers in the UK.
The Cancer Research UK charity estimates that 23,000 women will develop cancer due to obesity by 2035.
Obesity will also be the leading cause of cancer in women by 2043 if this trend continues.
The study also revealed that severe deficiencies were associated with several other causes of death, such as "dementia, Alzheimer's disease, heart and suicide."
However, Bhaskaran said that the link between low BMI and cause of death was more "conservative" because it was unclear whether leanness was directly related to the disease or whether it was merely a sign of poor health.
He also acknowledged that this study was still limited due to lack of information on the types of food consumed and also individual physical activity. But Bhaskaran emphasizes the importance of maintaining a BMI between 21 and 25. [bbc]