Postprandial triglycerides, flow-mediated dilation, and inflammatory cytokines as candidates for early risk detection in normal-weight obesity and metabolically healthy obesity

Objectives: Individuals with metabolically healthy obesity (MHO) and normal-weight obesity (NWO) often present with clinically unremarkable risk profiles despite evidence of increased cardiovascular disease (CVD) risk. We therefore examined whether other, less-utilized cardiometabolic risk factors may be abnormal in these populations, consistent with their potential CVD risk. Methods: Two studies were conducted (N=41) measuring postprandial triglycerides after an abbreviated fat tolerance test (9 kcal/kg; 70% fat), the indicator of vascular health flow-mediated dilation (FMD) both pre- and post-high-fat meal, and a panel of fasting inflammatory cytokines. Study 1 evaluated these measures in MHO (body mass index [BMI] > 30 kg/m²; 0-1 metabolic syndrome [MetS] components) compared to metabolically healthy, normal-weight controls (BMI 18.5-24.9 kg/²2; 0-1 MetS components) and individuals with obesity and MetS (BMI > 30 kg/m²; 2+ MetS components). Study 2 examined the same parameters in NWO (BMI 18.5-24.9 kg/m²; body fat percent > 25% [M] or > 35% [F]) versus low body fat percent, normal-weight controls (BMI 18.5-24.9 kg/m²; body fat percent < 25% [M] or < 35% [F]; 0-1 MetS components) and those with obesity, high body fat percent, and metabolic syndrome (> 30 kg/m² body fat percent > 25% [M] or > 35% [F]; 2+ MetS components). Results: In study 1, MHO displayed similar postprandial triglycerides to normal-weight, metabolically healthy controls, and both groups were lower than MetS (p < 0.01). MHO and MetS both presented with lower fasting FMD than controls, but MHO did not experience the same decrease in FMD following the high-fat meal as other study groups (p = 0.39). Relative to controls, and in some cases MetS, MHO displayed consistent evidence of low-grade inflammation (e.g., higher interleukin [IL]-1β, IL-6; p’s < 0.05). In study 2, NWO participants had similar fasting triglycerides to normal-weight, lower body fat controls, but all groups differed with respect to postprandial triglycerides such that MetS > NWO > controls (p < 0.05). Conversely, NWO had similar flow-mediated dilation metrics and inflammatory mediators compared to low body fat counterparts. Conclusion: Overall, both MHO and NWO displayed evidence of increased CVD risk when these nontraditional risk factors were considered.