I agree brister, my sisters 13 pounder is so muscular and fit he's just bigger framed. He could be mixed as well he is a rescue from Oklahoma (we did a yorkie talk train!! It was awesome!) so no idea if he's full yorkie, 100% looks it but just tall. He's def not a bit overweight. My boy I'm afraid is a bit. I did use your guideline, I do see a waist line but the ribs are not as easily felt as my females. Vet said diet as follows. Canned I/D 2 tbs per day (breakfast n dinner) and 1/2 cup of kibble a day. The only treats are green beans and baby carrots. Strictly no table food (besides veggies) due to pancreatis. Think that's a reasonable diet? It maintains my females perfectly. Diggy is still more "chubby"