Introduction
Obesity is a heterogeneous condition in which a subset of individuals maintain preserved metabolic health despite excess body weight. Reliance on body mass index alone fails to capture this heterogeneity, underscoring the need for body composition–based phenotyping to better distinguish metabolically healthy from metabolically unhealthy obesity.
Aims & Methods
This study aimed to compare lifestyle factors, anthropometry, biochemical parameters, imaging findings, and body composition assessed using bioelectrical impedance analysis (BIA) between metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO). This was a single-centre observational cross-sectional study conducted at AIG Hospitals between January 2024 and January 2025. Adults aged ≥18 years with a body mass index (BMI) ≥30 kg/m² were included. MHO was defined by systolic blood pressure <130 mm Hg without antihypertensive therapy, a waist-to-hip ratio <0.95 in women and <1.03 in men, and the absence of prevalent diabetes mellitus.
Body composition was assessed using a phase-sensitive single-frequency BIA device. The study included 132 adults with obesity, equally divided between MHO (n = 66) and MUO (n = 66). Demographic characteristics, lifestyle habits, comorbidities, anthropometric measurements, biochemical parameters, ultrasound-based abdominal fat distribution, and BIA-derived body composition metrics were compared between groups.
Results
Age and sex distribution were comparable between groups (p > 0.05). Regular physical activity was more common in MHO, whereas a sedentary lifestyle predominated in MUO (p < 0.05). MUO individuals had a significantly higher prevalence of hypertension, diabetes mellitus, dyslipidaemia, and cardiovascular disease (all p ≤ 0.04).
Anthropometric measures, including waist circumference, hip circumference, and waist-to-hip ratio, were significantly higher in MUO (all p < 0.001). Biochemical analysis revealed significant metabolic derangements in the MUO group, with higher fasting blood glucose (120.7 ± 22.8 vs. 88.5 ± 6.3 mg/dL) and HbA1c levels (7.8 ± 1.2% vs. 5.5 ± 0.4%) (both p < 0.001). Lipid profiles were similarly adverse, with higher total cholesterol (234.6 ± 36.9 vs. 182.3 ± 24.5 mg/dL), triglycerides (198.2 ± 54.5 vs. 110.4 ± 32.7 mg/dL), and LDL cholesterol (152.5 ± 34.1 vs. 105.2 ± 20.3 mg/dL), and lower HDL cholesterol (40.2 ± 8.4 vs. 55.8 ± 7.6 mg/dL) (all p < 0.001).
Ultrasound imaging demonstrated predominant normal fat distribution in MHO, whereas increased visceral fat accumulation was significantly more frequent in MUO (p < 0.001). Compared with MHO, MUO individuals had higher body fat percentage (38.6 ± 5.7% vs. 29.4 ± 4.1%), visceral fat level (15.1 ± 3.5 vs. 7.8 ± 2.2), and fat mass (32.8 ± 8.1 kg vs. 22.5 ± 5.6 kg) (all p < 0.001). Fat-free mass, skeletal muscle mass, and total body water were comparable between groups (all p > 0.05).
Conclusion
Despite similar demographic profiles, MUO is characterised by adverse lifestyle patterns, excess visceral adiposity, and marked metabolic derangements. These findings suggest that fat distribution rather than lean mass is a key determinant of metabolic health in obesity, underscoring the importance of body composition assessment for precision obesity phenotyping.
References
Zembic A, Eckel N, Stefan N, Baudry J, Schulze MB. An empirically derived definition of metabolically healthy obesity based on risk of cardiovascular and total mortality. JAMA Network Open. 2021;4(5):e218505. doi:10.1001/jamanetworkopen. 2021.8505
