Young adults aged between 20 and 29 showed the highest losses of healthy life-years due to obesity.
The researchers behind the study analyzed data from the US National Health and Nutrition Examination Survey (NHANES), creating a disease-simulation model to estimate the risk of adults of different body weight developing diabetes and cardiovascular disease.
From this, the researchers then calculated the extent to which overweight and obesity may contribute to both years of life lost and years of healthy life lost in American adults aged between 20 and 79 years old, in comparison to people of normal weight.
They found that people who were overweight (BMI 25-30 kg/m2) were estimated to lose up to 3 years of life, depending on age and gender. Individuals classed as obese (BMI 30-35 kg/m2) were calculated to lose up to 6 years, and people classed as very obese (BMI 35 kg/m2 or more) could lose up to 8 years of life.
According to the study, excess weight had the greatest impact on lost years of life among the young and dropped with increasing age.
Obesity can cause the loss of up to 19 'healthy life-years'
As well as reducing life expectancy, carrying extra weight was also found to reduce "healthy life-years," which were defined in the study as years free of obesity-linked cardiovascular disease and diabetes.
Young adults aged between 20 and 29 showed the highest losses of healthy life-years, adding up to around 19 lost years for very obese people. Among people who were overweight or obese, the researchers calculated that two to four times as many healthy life-years were lost than total years of life lost.
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 in Canada, explains the findings:
"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."
This week on Medical News Today, we also looked at a study published in The BMJ that found obesity during early pregnancy is a risk factor for infant mortality.
The researchers behind that study found that infant mortality was "moderately increased" among overweight and mildly obese mothers (BMI 25-35 kg/m2) compared with mothers of a normal weight; but among more obese mothers (BMI over 35 kg/m2), the risk of infant mortality was more than doubled.
We also reported on a study in the journal Preventing Chronic Disease that found women - particularly black women - are more at risk of increased obesity if they work jobs that involve a lot of sitting down.