Effect of the COVID-19 Epidemic on Body Mass Index: Findings from a Large Survey during Wuhan Lockdown

Table 4

Mediation analysis on factors mediating the association between BMI (body mass index) and living in Wuhan, by total, sex, age group, and weight status during the lockdown period. Wuhan, China, 2020.

Group	Variable	Model 3^a; (BMI)		Model 4^b; (Δ food habits affected)		Model 5^c; (Δ physical activity change)		Model 6^d; (BMI)
		β (95% CI)		β (95% CI)		β (95% CI)		β (95% CI)
Total	Living in Wuhan	0.42 (0.28–0.56)	<0.001	0.12 (0.09–0.15)	<0.001	0.10 (0.05–0.15)	<0.001	0.42 (0.28–0.56)	<0.001
	Food habits affected	—	—	—	—	—	—	−0.08 (−0.18–0.02)	0.133
	Physical activity change	—	—	—	—	—	—	0.10 (0.04–0.15)	0.001
Male	Living in Wuhan	0.41 (0.21–0.60)	<0.001	0.11 (0.07–0.15)	<0.001	0.11 (0.04–0.17)	0.001	0.40 (0.21–0.60)	<0.001
	Food habits affected	—	—	—	—	—	—	−0.03 (−0.16–0.10)	0.642
	Physical activity change	—	—	—	—	—	—	0.06 (−0.02–0.13)	0.142
Female	Living in Wuhan	0.40 (0.20–0.60)	<0.001	0.14 (0.10–0.18)	<0.001	0.09 (0.01–0.16)	0.024	0.41 (0.21–0.61)	<0.001
	Food habits affected	—	—	—	—	—	—	−0.13 (−0.27–0.02)	0.100
	Physical activity change	—	—	—	—	—	—	0.14 (0.06–0.22)	0.001
18–29 y	Living in Wuhan	0.46 (0.23–0.70)	<0.001	0.12 (0.08–0.17)	<0.001	0.04 (−0.04–0.11)	0.344	0.47 (0.24–0.70)	<0.001
	Food habits affected	—	—	—	—	—	—	−0.10 (−0.28–0.09)	0.310
	Physical activity change	—	—	—	—	—	—	0.08 (−0.03–0.19)	0.165
30–44 y	Living in Wuhan	0.45 (0.25–0.66)	<0.001	0.13 (0.09–0.17)	<0.001	0.15 (0.08–0.22)	<0.001	0.43 (0.23–0.64)	<0.001
	Food habits affected	—	—	—	—	—	—	0.02 (−0.14–0.17)	0.847
	Physical activity change	—	—	—	—	—	—	0.12 (0.04–0.21)	0.005
45+ y	Living in Wuhan	0.15 (−0.18–0.49)	0.374	0.12 (0.04–0.20)	0.002	0.07 (−0.07–0.21)	0.301	0.18 (−0.16–0.51)	0.297
	Food habits affected	—	—	—	—	—	—	−0.20 (−0.38–0.03)	0.023
	Physical activity change	—	—	—	—	—	—	0.06 (−0.04–0.16)	0.270
Underweight	Living in Wuhan	−0.03 (−0.15–0.10)	0.664	0.16 (0.06–0.26)	0.002	0.02 (−0.14–0.19)	0.799	−0.02 (−0.15–0.10)	0.697
	Food habits affected	—	—	—	—	—	—	−0.02 (−0.12–0.08)	0.702
	Physical activity change	—	—	—	—	—	—	0.01 (−0.04–0.06)	0.726
Normal weight	Living in Wuhan	0.08 (−0.00–0.17)	0.058	0.13 (0.09–0.16)	<0.001	0.08 (0.02–0.15)	0.012	0.08 (−0.00–0.17)	0.058
	Food habits affected	—	—	—	—	—	—	−0.03 (−0.09–0.02)	0.259
	Physical activity change	—	—	—	—	—	—	0.06 (0.02–0.09)	0.001
Overweight/Obesity	Living in Wuhan	0.31 (0.08–0.54)	0.008	0.11 (0.06–0.17)	<0.001	0.12 (0.02–0.21)	0.014	0.30 (0.07–0.53)	0.011
	Food habits affected	—	—	—	—	—	—	0.06 (−0.08–0.20)	0.379
	Physical activity change	—	—	—	—	—	—	0.06 (−0.02–0.14)	0.123

^aModel 3 in Table 4 is adjusted for sex, age, marital status, educational attainment, hometown location, household income per capita in 2019, health status as affected by the pandemic, chronic disease, and changes in smoking and drinking habits. ^bThe dependent variable in model 4 is food habits affected, adjusted for the same covariates as in model 3. ^cThe dependent variable in model 5 is physical activity change, adjusted for the same covariates as in model 3. ^dThe dependent variable in model 6 is BMI, adjusted for two more variables (food habits affected and physical activity change) as compared with model 3.