The aim of the study is to assess alexithymia levels in obese patients using a multimethod measurement (TAS-20 and TSIA) to evaluate both possible differences between the two instruments and their relationship with body weight.54 obese patients, seeking surgical treatment, were enrolled. They completed a socio-demographic questionnaire, 20-items Toronto Alexithymia Scale and the Toronto Structured Interview for Alexithymia.Data analysis showed a significant positive association between TAS-20 and TSIA total scores (r=.28, p<.05), but only the TSIA score was positively related to body weight (r=.39; p<.001). Multivariable linear regression models showed the predictive effects of TSIA total score (beta=.41; p<.001) and difficulty in identifying feelings (DIF) (beta=.56; p<.001) respectively on weight.The findings showed a different association between body weight and alexithymia according to the instrument employed to evaluate alexithymia, supporting the importance of a multimethod assessment in some clinical conditions.