The treatment of obesity involves dealing with the psychological aspects, manipulating the diet and increasing the activity level. The objectives of the nutritional management are to decrease energy intake, to stimulate satiety and to provide a balanced nutritional intake that is appropriate for the stage of life and/or concomitant disease. The assessment of a diet for weight reduction should take into account the daily nutrient intake in order to avoid underfeeding of essential nutrients. The treatment of obesity will be illustrated with a complicated case of obesity and renal insufficiency in a dog.