Obesity has adverse consequences in the general population. In patients with chronic kidney disease (CKD), it is associated with increased inflammation, insulin resistance, hypertension and dyslipidaemia, which are important risk factors for CKD progression and death. In adults with CKD stages 1-4, weight loss should be encouraged, it reduces proteinuria and glomerular hyperfiltration, which are frequent in obese patients. Proposals for modifications of lifestyle, physical activity and calorie restriction are the first measures. Pharmacological treatments are generally unsafe in these patients, except orlistat, but that has modest efficacy. Bariatric surgery may be the only option in severe obesity, if all other measures fail. For obese patients on dialysis treatment, who are eligible for kidney transplantation, weight loss is mandatory to prevent obesity-related surgical complications and improve patient and graft survival after transplantation. Interventions should place an emphasis on exercise to increase muscle mass, and calorie but not protein restriction. Bariatric surgery should be carried out by experienced surgeons due to the high risk of complications. For obese patients who are not considered transplant candidates the benefits of weight loss remain uncertain.