Association of serum Klotho concentrations with abdominal obesity among middle-aged adults in the US: evidence from NHANES 2011-2016

The role of Klotho in metabolic processes and aging-related conditions is well-established. However, the link between Klotho and visceral adipose tissue (VAT) remains understudied. The aim of this study was to explore the relationship between Klotho levels and both VAT area and abdominal obesity. A cross-sectional analysis encompassing 3316 middle-aged individuals was conducted using data from the National Health and Nutrition Examination Survey (NHANES 2011 to 2016). Dual-energy X-ray absorptiometry (DXA) was utilized to assess the VAT region, while abdominal obesity was defined by a VAT area exceeding 100 cm². The relationship between Klotho and VAT area was evaluated using multiple linear regression, and the association between Klotho and abdominal obesity was assessed using multivariate logistic regression. To assess linearity and explore the dose-response curve, restricted cubic splines were applied. Higher Klotho levels were associated with a lower VAT area (β -5.57, 95% CI = -9.83 - -1.30; P = 0.011) and a reduced incidence of abdominal obesity (OR 0.57, 95% CI = 0.42-0.78; P < 0.001), after adjusting for all model variables. Furthermore, multivariate smooth splines analysis revealed a nonlinear, L-shaped relationship between Klotho and both VAT area and abdominal obesity. A significant negative association was observed, with the curves leveling off as Klotho levels increased beyond 1.155 ng/mL. An L-shaped nonlinear relationship between Klotho and the VAT area indicated a saturation effect. These findings warrant attention and suggest that further investigation into the association between serum Klotho and abdominal obesity is necessary.