Associations of BMI and Waist Circumference with All-Cause Mortality: A 22-Year Cohort Study

Objective This study aimed to examine the associations of BMI and waist circumference with all-cause mortality in a general adult population from the China Health and Nutrition Survey. Methods Based on the World Health Organization recommendations, the general adult population was divided into underweight (BMI < 18.5 kg/m(2)), normal weight (18.5 kg/m(2) <= BMI < 23.0 kg/m(2)), overweight (23 kg/m(2) <= BMI < 27.5 kg/m(2)), and obesity (BMI >= 27.5 kg/m(2)), as well as abdominal obesity (waist circumference value >= 90 cm for males and >= 80 cm for females). Results Overweight was associated with lower all-cause mortality in the 18- to 29-year-old and 30- to 39-year-old subgroups in males (P = 0.0490 and 0.0234; hazard ratio: 0.136 and 0.462, respectively), and underweight had the opposite association in the 50- to 59-year-old and >= 60-year-old subgroups in males (P = 0.0074 and 0.0398, respectively) and in all subgroups in females except the 30- to 39-year-old and 50- to 59-year-old groups (P = 0.0786 and 0.0538, respectively). Abdominal obesity was associated with lower all-cause mortality in >= 60-year-old females (P = 0.0071). Conclusions Overweight was associated with lower all-cause mortality in young males and middle-aged females, but underweight demonstrated the opposite association in all elderly participants. Abdominal obesity could decrease all-cause mortality in elderly females.