[rayray08]

My pup (7months old) had her days where she wouldn't eat till 2-3pm in the afternoon! It drove me crazy and nothing would entice her to eat. She just ate when she felt like it. She is bigger than your dog, she weighs 5.8lbs. She was spayed last Thursday and I don't know if it's just a coincidence but she's gotten better with eating. She will still only eat generally in the morning and night, maybe a few nibbles during the day. I plan to keep free feeding till she's 12 months old.

Oh and about the surgery, if the vet said no food or water after 12... that means no food or water. (Mine couldn't eat after 10pm) If you do feed them, they have to cancel the surgery. It's standard practice to protect your pet while under anesthesia. Same goes for us humans, we can't have food after a certain hour.
While under anesthesia it can cause nausea and vomiting. They don't have you eat because if you did eat and happened to vomit there's risk of it being aspirated into your lungs. This can be extremely dangerous and possibly even fatal.

If your concerned with hypoglycemia because he'll be restricted, talk to your vet before giving any karo syrup if he's going in for surgery.

Has he ever shown signs of hypoglycemia? If not and he's gone 10-11 hours w/o food, I wouldn't be too worried. Again it doesn't hurt to check with your vet to see what they say.