The simple answer is yes.
When using a reward-based system to train, you have to have a reward! This is typically food, praise, play, a toy, or a combination of these. Food is easy to deliver and allows for repeated repetitions within a short time frame, which makes it a popular choice. So working on the assumption that you've chosen to use food in training, read on!
The hungrier your dog is, the higher value your food reward will be. Most dogs can skip a meal without negative consequences, but if you're not sure of this - ask your vet! Many of my training sessions are planned, and my dogs eat twice daily. I can easily skip a feeding before each planned training session. For my dogs, this means I can use their meal for training, if I'm training in a medium distraction environment or I'm reinforcing behaviors for which my dogs have some reinforcement history. Watch your dogs weight. If he's underweight, increase the calories at meal times or only decrease meals before training rather than skipping entirely.
Use higher value food for highly distracting environments and for teaching new behaviors. This is a good rule of thumb when training with food. Some dogs will work for kibble wherever they are and are perfectly willing to learn new behaviors with whatever bits you happen to have in your pocket. Other dogs require a very high value reward if you change the environment even a little. If you're unsure, follow the general guideline. But always plan to have several different rewards of varying values with you when you train.
The more complex answer...
Sometimes having a hungry dog can be an impediment to training.
If you have a voracious eater who works for any food anywhere, you may have some special challenges. If your dog loses his mind in the presence of food, you may plan to feed regularly scheduled meals before sessions just to keep him from being frantic when you get the food out to train. Don't confuse enthusiasm for a frantic or anxious dog. Enthusiasm is good; frantic or anxious actually impedes learning. This is not most dogs, but you'll likely know if you have one.
Here are some clues for those of you with the food frantic or anxious dog. Your dog normally takes treats nicely from your hand, but when he's hungry he grabs hard at food and isn't careful with his teeth. Your dog isn't able to perform well-learned behaviors in the presence of food when he's hungry. These are not necessarily indicators but can be clues for some dogs.
Some dogs with a sensitive stomach may need a meal before training to help their digestion. If you're using a large quantity of high value treats, the change from the sensitive-stomached dog's diet can be unsettling. While it is always a good idea to use high quality food, even food choices that are good for your dog can be unsettling to his stomach simply because they're different. Of course, making wise choices with your training food is very important, but the best choices are typically discovered through trial and error since dogs are unique in their reactions to food. A few general rules to follow include:
1. Avoid large quantities of fatty, salty, or rich foods;
2. Muscle meat is usually tolerated better than organ meat; and
3. The canned version of your dog's food is usually well tolerated in small quanities.
If you're using very high value food that is rich, fatty, salty, or otherwise not as healthy as your dog's regular food, then feeding a partial meal before training may be wise. Think of this as eating pie but no entree beforehand - simply not a good idea for some dogs. Limit these types of foods, but if you plan to use them, help your dog's tummy as much as you can.
"My dog isn't interested in working for food..."
Look for my upcoming blog post on increasing food motivation!