Never had a dog who determined for themselves when they would/would not eat.
We fed our adult dogs 2/day - am and pm. Food left down about 20-30 minutes and then picked up and put away.
If they ate they ate, if not then had to wait for the next meal coming. They also got a few treats when training or if they were really cute!
Some dogs would "Scarf" their food and some were much more picky - as long as they were not sick - so what?
If they were hungry they ate and if not they didn't. Never really worried about it and used no special "additives" i.e. canned food or meat or juices.
Dogs are smart - start using these things and they come to expect them (Like we would!).