Feeding time is much different in our house.
There is no leaving food out, AKA "At Liberty Feeding", we have several dogs which would take advantage of this and pork out a any opportunity. There is a great amount of competitiveness for food about our dogs. I generally attribute this to having groups of three or more.
There are very beneficial reasons to feed at a specific time. Pavlov’s Dog, which documented that dogs anticipate a specific feeding time and or conditions in which they salivate and produce digestive acid. Feeding on a regular schedule does aid in the digestive process. This also very beneficial to producing regularity for bowel movements, a big plus for puppy house breaking.
As for time of day, if your dog tends to be overweight, feed in the morning only. The dog will burn the Kcals thought out that day, and extra will be stored as fat, or if insufficient to meet that days needs, they will burn fat reserves. This allows better weight management for the dog which tends to be fat.
If your dog tends to be thin, feed twice a day. The dog will burn the Kcals given in the morning, and the evening feeding will assist in supplying additional Kcals and reduce the likelihood that they will pull from fat reserves. The additional Kcals from the evening feeding will be processed into fat reserves if the dog does not utilize them, such as during that nights sleep. This helps to keep weight on the dogs that tends to be thin.
Remember, a dog’s digestive system is very different from humans. In the wild, canines do not eat on a regular schedule, often going several days between meals. They gorge themselves when the do feed, and sleep shortly after, putting as much of the Kcal into fat reserves as possible. We humans do not have the metabolism to process calories into fat then burn that fat on a fest – famine demand. Our metabolism wants to slow down before burning those fat reserves when faced with famine.