Clinical Obesity Among Chinese Adults: Prevalence, Multimorbidity Burden, and Associations with Physical Activity

Figure 1. Study flowchart and operational classification algorithm. Notes: Participants were from CNHS 2015 and restricted to adults aged 18–79 years. Individuals were excluded if their age was out of range or if their height/weight or waist circumference data were missing. “Excess adiposity” was operationalized using BMI and central adiposity indicators: (1) BMI ≥ 28 kg/m2 and (WC ≥ 90 cm in men or ≥85 cm in women or WHtR ≥ 0.50); (2) BMI < 28 kg/m2 and (WC ≥ 90 cm in men or ≥85 cm in women and WHtR ≥ 0.50); or (3) BMI ≥ 40 kg/m2. Among participants with excess adiposity, “presence of clinical disease” indicates clinical obesity, whereas “absence of clinical disease” indicates preclinical obesity (clinical diseases defined as in Methods). Numbers shown in the flowchart are unweighted counts (n).

Figure 2. Prevalence of clinical obesity by sex and population subgroups in CNHS 2015. Notes: Blue indicates men, red indicates women, and green indicates overall estimates. Points indicate prevalence estimates, and horizontal lines represent 95% confidence intervals. Estimates are shown overall and stratified by age group (18–39, 40–59, ≥60 years), residence (rural/urban), region (Eastern/Central/Western), and physical activity category (MET-min/week: very low 0–300, low 300–600, medium 600–1200, high 1200–3000, very high ≥3000). Clinical obesity was defined as excess adiposity with ≥1 obesity-related clinical disease.

Figure 3. Distribution of comorbidity counts among adults with clinical obesity in CNHS 2015. Notes: Stacked bars show the percentage of adults with clinical obesity who had 1, 2, or ≥3 obesity-related comorbidities, presented overall and by sex within each age group (18–39, 40–59, and ≥60 years). Percentages may not sum to 100% due to rounding.

Figure 4. Prevalence of specific comorbidities among adults with clinical obesity. Notes: Bars show the prevalence (%) of each comorbidity among adults with clinical obesity, presented overall and by sex. Comorbidities include dyslipidemia, hypertension (HTN), diabetes mellitus (DM), chronic obstructive pulmonary disease (COPD), ischemic stroke, hemorrhagic stroke, asthma, angina, malignancy, myocardial infarction (MI), atrial fibrillation (AF), percutaneous coronary intervention/stent (PCI/stent), and coronary artery bypass grafting (CABG). Clinical obesity was defined as excess adiposity with ≥1 obesity-related clinical disease.

Figure 5. Association between physical activity and ordered obesity status. Notes: The very low PA group served as the reference category. Green indicates overall estimates, blue indicates men, and red indicates women. Points show cumulative odds ratios (cORs), and horizontal lines show 95% confidence intervals from proportional odds ordinal logistic regression models for higher ordered obesity status (no obesity → preclinical obesity → clinical obesity), presented overall and by sex. Physical activity (PA) was categorized by MET-min/week as very low (0–300), low (300–600), medium (600–1200), high (1200–3000), and very high (≥3000). The proportional odds assumption was tested before model interpretation and was considered acceptable for the final models. Model 1: unadjusted (crude). Model 2: adjusted for age group. Model 3: additionally adjusted for residence (rural/urban) and region (Eastern/Central/Western). Model 4: additionally adjusted for smoking, alcohol drinking, total energy intake, and percent energy from fat (restricted to participants with complete dietary and lifestyle covariate data). Models 1–3 used n = 177,411, and Model 4 used n = 60,322.