How can I stop my dog being hysterical over food?

"we haven't always been totally consistent with our training methods". That's the key I think. A dog is supposed to be fed at a fixed time and there should be only one person who's responsible for feeding him. If he can beg and get food from anybody, it is a spoiled dog. I once had a dog obsessed with food like yours, though the problem was not as acute, and I settled that with firm discipline: I fed him a slightly reduced portion in the morning, then an extra handful at supper time to keep him quiet. Nothing at all in between no matter how he begged. And of course, nobody else interfering to nullify the discipline. For the shrieks, spray him with bottled water, like a windex bottle. It's painless and very efficient so long as your are consistent in getting the bottle every single time.