Background:
Many studies have shown controversial results in the relationship between weight change and mortality. Therefore, we investigated the relationship between weight change and subsequent all-cause mortality using a large-scale population-based cohort from The National Health Insurance System (NHIS) health checkup data from 2005 to 2015.
Methods:
Total 11,524,763 subjects who were 20 years old were included (men= 6,327,210 and women = 5,197,553) The weight change was calculated as the difference of body weight during 4yrs which is between 1st and 3rd health checkup and we divided the weight change group into 8 categories from loss ≥ 15% to gain ≥ 20% for every 5% change. All-cause mortality was assessed 5.2±1.2 years after last weight assessment. The hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause mortality were analyzed using multivariable Cox’s proportional hazard models.
Results:
Weight loss caused more mortality than weight gain, and weight loss≥15% group had the highest HR of all-cause mortality (HR;95% CI=2.925;2.857-2.995) and HR of all-cause mortality in weight gain ≥ 20% was 1.788. In all BMI categories, weight loss ≥ 15% shows the highest mortality and the highest mortality was found in the BMI ≥ 30 kg/m2 group (HR;95% CI=3.665;2.361-5.689). Both weight stable group (normal to normal BMI group and obesity to obesity BMI group) showed reverse J-shaped mortality curve and sustained normal weight group showed higher HR of mortality in weight loss than sustained obese group.
Conclusions:
In conclusions, weight change over a 4-year period shows reverse J-shaped all-cause mortality curve regardless of BMI status. Both weight loss and weight gain caused increased mortality and weight loss is greater risk in increasing mortality than weight gain. Further studies on cause specific mortality according to weight change is also needed.