Trends and characteristics of the metabolically healthy obese phenotype in an Arab population

Abstract

The metabolically healthy obesity (MHO) phenotype represents a complex and distinctive trait, the trends and characteristics of which remain unknown in the Saudi Arabian adult population. The present study aims to fill that gap. A combined total of 10,220 Saudi adults from 2 independent cohorts [2008-2019, N = 7,896 (2,903 males and 4,993 females), and 2021-2023, N = 2,324 (830 males and 1,494 females)] aged 19-70 years old was screened, of whom 9,631 (3,428 males and 6,203 females) were included. Anthropometric data were measured, and fasting blood samples were collected to assess glucose, lipids, adipocytokines and inflammatory markers using routine methods and commercially available assays. Obesity was defined as a body mass index (BMI) ≥30 kg/m². Screening for MHO was done using the empiric definition proposed by Zembic and colleagues and the by the National Cholesterol Education Program's Adult Treatment Panel III (NCEP ATPIII). Of the 3,949 (41.0%) participants with obesity, 33.4% (95% confidence interval, CI, 32-35) were considered MHO using the empiric definition, and 32.8% (95% CI, 31-34) using NCEP-ATPIII. The overall age and gender adjusted prevalence of MHO in the Saudi adult population was 31.6% (95% CI, 30-33) and 30.1% (29-31) by the two definitions, respectively. Females had a higher age-adjusted prevalence of MHO than males (OR = 1.22, 95% CI 1.1-1.4, p = 0.009) as per the ATPIII criteria. MHO prevalence substantially increased over time from 2008 to 2023 (p < 0.001) for both definitions. Circulating leptin levels and insulin resistance were significantly higher in the MUO group than the MHO group independent of the definition used, suggesting the presence of a more severe form of leptin resistance in the MUO group which may explain the worse cardiometabolic profile as compared to the MHO group. In summary, the study highlights the first time the characteristics and trends of the MHO phenotype among Saudi Arabian adults. The pluripotent effects of leptin and its resistance may be central to MHO's progression, or lack thereof, to the MUO phenotype, and this needs further investigation.

Keywords: Arab population; chronic diseases; epidemiology; metabolically healthy obesity; obesity.

Figure 1

Flow chart of the sample recruitment.

Figure 2

Bar graphs representing the prevalence of different components used for the two definitions of MHO in the study cohorts. The prevalence was calculated among those with obesity. For Empiric criteria, components are represented by C1: waist height ratio < 1.03 in males and < 0.95 in females; C2: absence of diabetes; and C3: systolic blood pressure < 130 mmHG, respectively. For NCEP ATPIII criteria, components are represented by C1: waist circumference of ≥102 cm and ≥ 88 cm in males and females respectively; C2: HDL-cholesterol levels of <1.03 mmoL/L and < 1.29 mmoL/L in males and females respectively; C3: fasting glucose levels of ≥5.6 mmoL/L or diabetes diagnosis; C4: triglyceride levels of ≥1.7 mmoL/L; and C5: blood pressure of ≥130/85 mmoL/L. An explanation of the two criteria has been provided in section 2.3.

Figure 3

Age-specific prevalence of MHO using the empiric definition (30) (A) and NCEP ATP III (31) (B) among obese subjects.

Figure 4

Time-series prevalence of MHO using the empiric definition (29) (A) and NCEP ATP III (30) (B) among obese subjects.