What Is Body Condition Score (BCS)?
BCS is a 9-point veterinary scale: 1 = emaciated, 5 = ideal, 9 = severely obese. It assesses body fat and muscle, not just weight. BCS is a 9-point scale developed by WSAVA to assess body fat and muscle mass — 1 is emaciated, 5 is ideal, 9 is severely obese. Unlike weight alone, BCS accounts for body frame and breed differences. A healthy cat at BCS 5 has palpable ribs with a light fat cover, a visible waist from above, and a tucked abdomen from the side.
Source: WSAVA Nutritional Assessment Guidelines