Purina veterinary diets feline om obesity management is a special diet that can help overweight or obese cats to lose excess weight there are a number of reasons why cats can gain weight including changes in their metabolism however it is mainly due to consuming too many calories with too little exercise being overweight can cause long term health problems which is why it is important to help your cat to regain a healthy weight using a special diet such as purina veterinary diets feline o