The gene TAS2R38 single nucleotide polymorphisms (SNPs-P49A, A262V and V296I) can condition bitter tasting by PAV (proline–alanine–valine) and non-bitter-tasting by AVI (alanine–valine–isoleucine) homozygosity. We evaluated this polymorphisms association with thyroid function, metabolism and anthropometry parameters determined by: Endpoint analysis (SNPs); DXA (fat mass-%, total fat mass—kg, lean mass—kg); Standard methods (lipid metabolism parameters, HbA1c-%, glycemia—mg/dL, insulinemia—µIU/mL, HOMA-IR, uricemia—mg/dL, calcemia—mg/dL and BMI—kg/m²); ELISA (leptinemia—ng/mL); Spectrophotometry (Angiotensin Converting Enzyme activity—UI/L). Statistics: SPSS program; OR [IC95%]; p < 0.05. Sample: 114 hypothyroid, 49 hyperthyroid, and 179 controls. An association between A262V-valine–valine and hypothyroidism/hyperthyroidism was verified (OR = 2.841; IC95% [1.726–4.676]), p < 0.001/OR = 8.915; IC95% [4.286–18.543]), p < 0.001). Protector effect from thyroid dysfunction: A262V-alanine–valine (OR = 0.467; IC95% [0.289–0.757], p = 0.002/OR = 0.132; IC95% [0.056–0.309], p < 0.001) and PAV (OR = 0.456; IC95% [0.282–0.737], p = 0.001/OR = 0.101; IC95% [0.041–0.250], p < 0.001). Higher parameter values associated with genotypes were: fat-mass-% (V296I-valine–isoleucine), lean-mass (P49A-proline–proline; PVI), leptin (AVI), HbA1c (A262V-alanine–valine) and lower values in lean-Mass (AVI; PVV), leptin (A262V-alanine–alanine), HbA1c (PVV), uricemia (V296I-valine–isoleucine), glycemia (A262V-alanine–alanine; AAV) and plasma triglycerides (PVV). In conclusion, TAS2R38 influences thyroid function, body composition and metabolism. Bitter taste perception (PAV) and the genotype A262V-alanine–valine can protect from thyroid dysfunction. AVV, PVV and genotype A262V-valine–valine may confer higher predisposition for thyroid dysfunction, particularly PVV for hyperthyroidism.