Obesity in companion animals is a common clinical condition, and represents an important challenge to the veterinarian. This paper reports a study in which controlled calorie reduction was used to achieve weight loss in a group of dogs. The food allowance for the study provided approximately 209 kJ metabolisable energy (ME)/kg (target weight)0.75/day, with target weight 15% less than the dog's starting weight. The rate of weight loss achieved averaged approximately 1% per week over a 12 week period. Data reviewed from a second study in cats suggested that an energy intake of approximately 121 kJ ME/kg target weight/day, again with the target 15% less than the current weight, was an appropriate level for obtaining gradual weight loss in this species. These findings are discussed in relation to an alternative method of weight reduction, starvation. The potential value of exercise as an adjunct to controlled calorie reduction for achieving weight loss in companion animals is also considered.