Introduction : The advent of immune checkpoint inhibitors (ICI) such as nivolumab has enabled outcomes for metastatic renal cell carcinoma (mRCC) to be improved. Although, only around 25% of patients respond to these therapies without being able to formally identify them. Datas on relevant predictive markers are still laking. The obesity paradox has been shown as a relevant prognostic marker in mRCC with better outcomes for obese patients. Nevertheless, the impact of weight variation and the presence of sarcopenia during ICI is not known for now. Methods : In a retrospective study, weight and its variations were collected at first day of ICI and at 6 weeks of treatment. Scanographic imagery was used to define the skeletal muscle index (SMI) as a reflect of sarcopenia. The impact of these parameters as predictive and prognostic factors for mRCC with nivolumab was evaluated. Results : A higher BMI at baseline was significantly associated with response at the first scan (p=0.036). Longer OS was observed for patients with a weight gain compared to the group with weight loss (p=0.00028). Median OS for sarcopenic patients was 17.2 months, and 31.6 months for the non-sarcopenic group of patients, but there was no statistical difference. Conclusion : This trial showed that a higher BMI and weight gain during nivolumab treatment were good predictive markers for outcomes in mRCC with nivolumab. Sarcopenia and variations in SMI could thus be of interest, but further studies are required.