According to the information provided on Purina's website, Purina ONE Healthy Weight dog food contains 15% fewer calories and 25% less fat compared to Purina ONE Lamb & Rice Formula. This indicates that Purina ONE Healthy Weight is formulated with reduced fat content, making it a suitable option for dogs who need to manage their weight or maintain a healthy weight. However, these percentages may vary slightly depending on the specific product within the Purina ONE Healthy Weight line. For more precise details on the fat percentage of a particular product, we recommend referring to the product packaging or contacting Purina directly.