A different angle is to maybe re-evaluate his eating schedule. Sounds like he may not really be that hungry when it's time to eat. Maybe more time in between meals/snacks, and I know folks are always hesistant to wean, but my ped told us that if DS ate less at night, he'd eat more during the day. At 11 months, I believe that's when they start telling you that food is going to become more important than BM/formula soon....
Just a thought.