The aims of this study were to (1) identify the association between carriage of PNPLA3 rs738409 genotype and change in bodyweight (BW) and LSM, and (2) determine whether such HSD17B13 rs6834314 genotype influences the effect of the PNPLA3 rs738409 G variant, concerning the response to diet therapy in Japanese patients with biopsy-proven NAFLD. This evidence concerns the gene PNPLA3 and metabolic dysfunction-associated steatotic liver disease.