Orocecal transit time (OCTT) is one of the main determinant of the hunger ratings and gastrointestinal sensitivity. While marked-isotopes scintigraphy is the gold standard in its determination in the clinical frame, breath tests are cheap, well-tolerated and non-invasive alternatives. In fact C-13 and C-14 stable isotopes breath tests can be used to assess gastric emptying and OCTT in the clinical and research frames. Moreover, hydrogen (H2) lactulose breath test can be used to assess OCTT in the research frame only due to its laxative action; inulin breath test, devoid of this bias, could be replacing it. However, the main limitation in the use of breath tests in the OCTT determination is their low reproducibility.