Prevalence, time trends and associated factors of adult overweight and obesity in 36 countries in the WHO African region from 2003 to 2022: a study of 54 WHO STEPS surveys representing 156 million adults

BACKGROUND: We investigated the prevalence, temporal trends and associated factors of overweight and obesity among adults in the WHO African region. METHODS: We analysed individual-level data from 54 nationally/sub-nationally representative STEPS surveys conducted between 2003 and 2022 among adults aged 18-69 years. Prevalence estimates were weighted and age-standardised. Time trends were estimated using a Bayesian spatiotemporal modelling approach. Factors associated with body mass index (BMI) categories were identified in hierarchical multinomial mixed-effects logistic regression with random effects for country and survey year, using the normo-weighted as the reference group. RESULTS: (24.23±1.60 in women and 22.11±1.53 in men, p for sex difference <0.001). The prevalence of overweight and obesity was 17.8% and 9.0%, respectively, higher in women (20.8% and 13.3%) than in men (14.9% and 4.6%). There was no significant time trend in mean BMI (23.25 kg/m² (95% CI 20.1 to 26.6) in 2003 and 23.43 kg/m² (95% CI 19.3 to 27.8) in 2022, p for trend=0.75). However, obesity prevalence increased from 15.39% to 16.71% (p for trend <0.001), and underweight from 12.07% to 12.76% (p for trend <0.001), whereas overweight plateaued. In multivariate analysis, sex, older age, higher education, physical inactivity and low fruit and vegetable consumption increased the odds of overweight and obesity, whereas past and current smoking showed inverse associations. Specifically, adjusted odds ratios for overweight and obesity for females versus males were 2·07 [(95% CI: 1·83- to 2·34]) and 4.92 [(95% CI: 4·13- to 5·89]); for tertiary education versus no education, they were 2·07 [(95% CI: 1·63- to 2·63]) and 3·77 [(95% CI: 2·77- to 5·11]), respectively. CONCLUSION: These findings support the urgent need to intensify preventive programmes to fight obesity in the WHO African region.