1) Opportunity - This is the most common reason that affects Beagles of any age, from a hyper little 3 month old to an older, senior dog.
Food stays in a dog's stomach for a much longer time than humans. In fact, as soon as we owners take our first bite, our saliva immediately begins the first step of digestion. For our Beagles, this does not happen until the food enters the stomach.
It can be up to 3 full days from the time our puppy or dog ingests his meal until it is completely processed and unused elements are eliminated. This is one reason why adult canines do not need 3 meals plus snacks like you and I do. So, a Beagle's stomach - if he is feed on a regular schedule of high quality sustenance- is rarely ever empty. Certainly not enough to cause him to have an insatiable appetite.
So, why would a Beagle act as if he is starving? The most common reason is that the opportunity to eat is presented to him and he will not turn the offer down. Some examples of this are:
You are cooking dinner, your Beagle smells it, comes over and looks at you with those amazing, pleading eyes. Is he hungry? Maybe not. But, his incredible sense of smell is telling him that some tempting morsels are available… his experience is that all he needs to do to obtain it is look at you a certain way.
You sigh and then you give in and hand him a piece of meat or bread. He gobbles it down and you say, "Why are you always hungry?" Well, he wasn't really starving, but he saw/smelled a chance to take in food and being a dog, he had to try. You didn't think he was going to sniff it and turn around, did you?
Even though canines have been domesticated for a long time, our pets will almost never turn down food.
The Fix: Since this breed can easily become overweight, especially seniors, it's best to feed scheduled meals and snacks. Little nibbles here and there can add up to cause excess weight gain.
Additionally, it can be a frustrating habit when a dog expects to have bits of food given to him whenever his owners eat. It's best break the expectation of being given edibles outside of meals and planned treats.
For puppies, treats are best reserved as rewards for training and for older Beagles snacks are best for reinforcing good behaviors such as listening to commands or following proper heeling techniques. You'll find that when you do not offer extra rations - even if your Beagle appears to be starving - that those treats will have more meaning when put into the context of reward.
2) Inadvertent Reinforcement - One tricky trap that owners can find themselves falling into is a Beagle that has learned that making certain faces or positioning himself a certain way causes his owner to give him food. This habit is quickly learned; sometimes all it takes is 2 times of this happening for the habit to settle in.
Beagles that have learned this are essentially thinking that making 'puppy dog eyes' or acting a certain way 'rewards' them something to eat. When it all boils down, it is similar to a dog performing a trick and being given a treat. For some dogs, always acting as if they are starving is just a matter of a dog obtaining 'easy food', which is food offered to him for very little effort on his part.
The Fix: Take a few days to see if you can find a pattern of behavior and have all members of the family involved. For example, your child might confess to giving a treat when your Beagle flops down and wiggles on his back… "It's just so cute, I give him a bit of food after he does it". Some members of the family (you?) might throw down a piece of sandwich meat just because your dog sat and stared while lunches were being made… all he needed was those big, beautiful eyes.
Don't reward for poses or expressions. Give praise or verbal recognition instead and save the food for when your Beagle is truly hungry.