BACKGROUND/OBJECTIVES: Thyroid hormones (THs) are correlated with body composition regardless of the presence of thyroid dysfunctions, whereas little is known regarding THs' influence on muscular fitness components. This cross-sectional study investigated whether THs may affect muscular parameters in adults who are overweight and affected obesity. METHODS: One hundred and five volunteers (65 females and 40 males, BMI: 33.5 (8.0) kg/m RESULTS: In the female group, the Pearson linear regression analysis revealed a positive correlation between FT3 and HG (R = 0.261, CONCLUSION: FT3 and FT3/FT4 ratio levels in euthyroidism may influence muscular parameters differently in females and males affected by an excess of fat mass. More research is needed to understand the mechanisms behind this correlation and whether THs could be a potential biomarker for muscle-related parameters.