Background: Lymphedema is a medical condition that is an externalization of a lymphatic insufficiency. The aim of this study was to assess the effect of intensive lymphedema treatment on the body mass and fat mass Indexes. Method and Results: A clinical trial was performed using bio impedance to evaluate changes in the body mass and fat mass Indexes of 30 consecutive patients submitted to intensive lymphedema treatment of the legs (8 hours/day for one week) in the Clínica Godoy between 2013 and 2015. The paired t-test and Fisher’s exact test were used for statistical analysis with an alpha error of 5% being considered acceptable. Significant changes in the mean body mass (p-value = 0.0001) index was identified by comparing evaluations before and after treatment however there was no significant improvement in the fat mass index. In these cases, morbid obesity was associated with age over 40 years (Fisher’s exact test: p-value 0.01). Conclusion: A significant reduction of edema during the intensive treatment of stage III lymphedema can reflect in a significant reduction in the body mass index.