Obesity may shorten life expectancy by up to 8 years

Obesity and extreme obesity have the potential to reduce life expectancy by up to 8 years and deprive adults of as much as 19 years of healthy life as a result of type 2 diabetes and cardiovascular disease, a study suggests.

The study, published in The Lancet Diabetes & Endocrinology, used data from the US National Health and Nutrition Examination Survey to create a disease-stimulation model to estimate the risk of developing diabetes and cardiovascular disease in adults of different body weight. The researchers then analysed the contribution of overweight and obesity to years of life lost and healthy years of life lost in US adults of various ages between 20 and 79 years old, compared to people of normal weight.

Overweight individuals (BMI 25 to <30 kg/m2) were estimated to lose between 0 and 3 years of life expectancy, depending on their age and gender. For obese individuals (30 to <35 kg/m2) the years lost were between 1 and 6 years, whereas the very obese (35 kg/m2 or more) were estimated to lose between 1 and 8 years. The effect of excess weight on years of life lost was greatest for the young and dropped with increasing age.

Excess weight doesn’t just reduce life expectancy but also healthy life-years (defined as years free of obesity-associated cardiovascular disease and diabetes). The study shows that being overweight or obese is associated with two to four times as many healthy life-years lost than total years of life lost. The highest losses in healthy life-years were in young adults aged between 20 and 29 years old, amounting to around 19 years for very obese men and women.

Dr Steven Grover, lead author and  Professor of Medicine at McGill University and a Clinical Epidemiologist at the Research Institute of the McGill University Health Centre, Montreal, Canada, said: “The pattern is clear - 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.

“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.” 

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