Purina body condition system

How skinny is "pretty skinny"?  How heavy is "not as thin as he should be"?  The Purina body condition system provides a uniform way to describe a pet's weight, from "emaciated" to "grossly obese"

1. EMACIATED
   Ribs visible on shorthaired cats; no palpable fat; severe abdominal tuck; lumbar vertebrae and pelvic bones easily palpated.
2. VERY THIN
   Between 1 and 3
3. THIN
   Ribs easily palpable with minimal fat covering; lumbar vertebrae obvious; obvious waist behind ribs minimal abdominal fat.
4. UNDERWEIGHT
   Between 3 and 5.
5. IDEAL
   Well proportioned.  Observe waist behind ribs; ribs palpable with slight fat covering; abdominal fat pad minimal.
6. OVERWEIGHT 
   Between 5 and 7.
7. HEAVY
   Ribs not easily palpated, with moderate fat covering; waist barely visible; rounded abdomen, moderate abdominal fat pad
8. OBESE 
   Between 7 and 9.
9. GROSSLY OBESE 
   Ribs not palpable under heavy fat cover; heavy fat deposits over lumbar area, face and limbs; distension of abdomen with no waist; extensive abdominal fat deposits.