Obesity can reduce a person's life expectancy by eight years and shorten a chronic disease-free existence by up to 19 years, according to a study published on The Lancet, Britain's premier medical journal.
The research team, led by Dr. Steven Glover, of McGill University's health center in Montreal, Canada, developed a computer model to examine the disease incidence in relation to people's weight.
"Our computer modeling shows that obesity is associated with an increased risk of developing cardiovascular disease and diabetes that will, on average, dramatically reduce an individual's life expectancy and the number of years of leading a healthy life free from those chronic diseases, compared to people of normal weight," said Grover.
The researchers analyzed the effects of obesity and overweight on the years lost in life and healthy living for U.S. adults, aged between 20 and 79, compared to people with normal weight.
They found that overweight people (with a Body Mass Index, BMI, ranging from 25 to 30) are prone to lose 0-3 years in life expectancy, depending on their age and gender.
Obese people (BMI between 30-35) may see their life expectancy shortened by 1 to 6 years; while the very obese, whose BMI is higher than 35, are expected to lose 1 to 8 years.
The study shows that obesity highly affects young adults, aged between 20 and 29 years.
"The pattern is clear", says Grover. "The more an individual weighs and the younger their age, the greater the effect on their health, as they have many years ahead of them during which the increased health risks associated with obesity can negatively impact their lives," he said.
"These clinically-meaningful calculations should prove useful for obese individuals and health professionals to better appreciate the scale of the problem and the substantial benefits of a healthier lifestyle, including changes to diet and regular physical activity," Grover added.