Association of Thyroid Function and Hormone Sensitivity With Abdominal Fat in Individuals With Overweight and Obesity

ABSTRACT Aims The association between thyroid function and body fat distribution remains controversial, particularly regarding visceral and liver fat depots, which are highly predictive of cardiometabolic risk. We aimed to assess the associations of thyroid hormone levels and indices of thyroid hormone sensitivity with abdominal fat depots in adults with overweight and obesity. Materials and Methods This cross‐sectional study included 272 adults (53.3% women) with a mean body mass index (BMI) of 32.9 (5.9) kg/m 2 . Thyroid function parameters (TSH, FT4, FT3, TT4RI, TSHI, FT3/FT4) and abdominal fat distribution, including subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), liver fat content (LFC), and pancreatic fat content (PFC), were measured. Multivariate linear regression models were used to assess the association of thyroid parameters with abdominal fat depots, adjusting for age, sex, BMI, triglycerides, and total cholesterol. Results Higher TSH levels were associated with higher VAT ( β = 16.47; 95% CI: 6.30, 26.63) and LFC ( β = 2.87; 95% CI: 0.68, 5.05). Similarly, higher FT3 levels were associated with greater VAT ( β = 9.40; 95% CI: 0.45, 18.35) and LFC ( β = 2.17; 95% CI: 0.27, 4.06). Reduced central sensitivity to thyroid hormone, as suggested by higher TT4RI and TSHI, was associated with higher VAT ( β = 0.33; 95% CI: 0.11, 0.56) and LFC ( β = 1.98; 95% CI: 0.04, 3.93). Conclusions Higher TSH, higher FT3 levels, and variations in thyroid hormone sensitivity were associated with adverse visceral and hepatic fat accumulation in adults with overweight and obesity. These findings suggest a potential association between thyroid function and metabolically high‐risk fat distribution, warranting further investigation in longitudinal studies.