Background and significance:
Adult obesity has been linked with an increased risk of numerous adverse health outcomes and lower life expectancy (LE) when compared to healthy and overweight individuals. However, differences in life years lost (LYL) attributed to being overweight or obese in young adulthood has not been quantified in Australia.
Our aim is to predict remaining LE of Australian men and women aged 20-29 by body-mass index (BMI) categories: healthy (BMI 18.5-24.9 kg/m2), overweight (BMI 25.0 – 29.9 kg/m2), and obese (BMI >30.0 kg/m2). This is important in understanding the long-term consequences of obesity at a population level in Australia.
Methods:
We used a validated microsimulation model of obesity progression in Australia that integrates annual change in BMI based on age and sex, with Australian life table data and published relative risk of all-cause mortality for different BMI categories. Remaining LE and LYL estimated using an input population consisting of 3,226,902 adults aged 20-29 from the 2014/15 Australian National Health Survey.
Results:
Estimated remaining LE for healthy weight men and women aged 20-29 was approximately 57.0 (95% CI 56.7 – 57.4) and 59.8 (95% CI 59.4 – 60.0), respectively. Compared to those in the healthy BMI category, life years lost as a result of being overweight was approximately 4.2 and 3.6 years for men and women, respectively. For those with obesity in early adulthood the loss in life expectancy was predicted to be 9.0 and 6.9 years for men and women, respectively.
Conclusions:
Being overweight and obese in early adulthood results in a substantial loss of remaining life expectancy, particularly for men. The increasing trend towards obesity at younger ages suggests that this will be exacerbated in the future, and highlights the need for obesity prevention for targeted interventions in young adults in Australia.