Cachexia is common in patients with chronic kidney disease (CKD) and is associated with increased morbidity and mortality. Cachexia is a complex syndrome, in which inflammation and retention of uremic toxins are two main contributing factors. In this context, the role of the gut microbiome in CKD cachexia and the potential benefit of increasing the dialysis dose have been poorly explored. Here the investigators propose to study the links between cachexia and the gut microbiome, in association with inflammation and uremic toxins, in dialysis. The specific objectives are the followings: 1. Set up a prospective cohort of deeply characterized kidney failure patients treated with hemodialysis (in-center, self-care dialysis in a satellite unit and at home) and peritoneal dialysis, including evaluation of cachexia, body composition, collection of feces and blood to characterize the gut microbiota, measure serum levels of uremic toxins and inflammatory markers, with a longitudinal follow-up. 2. To compare cachectic versus non-cachectic dialysis patients in terms of gut microbiota, inflammatory markers, level of uremic toxins, muscle transcriptome, dialysis dose and modality. In a subgroup analysis, the investigators plan to compare the different techniques of dialysis (in-center vs home-hemodialysis vs peritoneal dialysis).