Epidemiologists have examined the relationship between body weight and life expectancy and say that overweight and obese individuals have the potential to decrease life expectancy by up to 8 years.

If diabetes or cardiovascular disease develop, that could shorten life expectancy ever more, according to their analysis of data from the National Health and Nutrition Examination Survey (years 2003 to 2010) which was used to estimate the annual risk of diabetes and cardiovascular disease in adults with different body weights.

The data from almost 4,000 individuals was also used to analyze the contribution of excess body weight to years of life lost and healthy years of life lost. 

The study, published in the current issue of The Lancet Diabetes and Endocrinology, further demonstrates that when one considers that these individuals may also develop diabetes or cardiovascular disease earlier in life, this excess weight can rob them of nearly two decades of healthy life.

Their findings estimated that individuals who were very obese could lose up to 8 years of life, obese individuals could lose up to 6 years, and those who were overweight could lose up to three years. In addition, healthy life-years lost were two to four times higher for overweight and obese individuals compared to those who had a healthy weight, defined as 18.5-25 body mass index (BMI). The age at which the excess weight accumulated was an important factor and the worst outcomes were in those who gained their weight at earlier ages.

"The pattern is clear - the more an individual weighs and the younger their age, the greater the effect on their health," says lead author Dr. Steven Grover, epidemiologist at the RI-MUHC and a Professor of Medicine at McGill University. "In terms of life-expectancy, we feel being overweight is as bad as cigarette smoking."

The next steps are to personalize this information in order to make it more relevant and compelling for patients. "What may be interesting for patients are the 'what if?' questions. What if they lose 10 to 15 pounds? Or, what if they are more active? How will this change the numbers?" says Grover.

The research team is now conducting a three year study in community pharmacies across the country to see if engaging patients with this information and then offering them a web-based e-health program will help them adopt healthier lifestyles, including healthier diets and regular physical activity.

"These clinically meaningful models are useful for patients, and their healthcare professionals, to better appreciate the issues and the benefits of a healthier lifestyle, which we know is difficult for many of us to adopt and maintain."