The real issue when choosing a dog food for your dog is that every dog is different. We're not just talking about the breed, even though they are different, but the two dogs of the same type may not even have the same eating habits. So to find the right dog food to keep your dog healthy, you will have to do a little detective work.
Breed: Start with the type of dog you have. Obviously small lap dogs will have different needs than say, a Great Dane. The size is a big factor in energy levels and digestive system. You can also visit https://www.drbslongevity.com/ to get the best dog food online.
Image Source: Google
Age: Puppies grow up and need a lot of good things to help them grow and to keep their energy up. They should be eaten in small amounts several times throughout the day like a baby. In dogs prime, say 3 years old for about 6 years, they may have a very healthy appetite at every meal, but only eat maybe twice a day.
Activity: Your dog is one of those kind of hyper dog who seems to be able to run all day until they collapsed at the end of the night? Or do you have a dog like my biggest ambition is to stretch after lying in bed all morning to walk 20 feet and go lie down in his favorite chair until he is hungry or having to relieve himself.
Stage in life: Sort of like age, but it is much more specific and may not be immortal. Things like an explosion of growth, recovering from injury, recovering from major surgery, day of extreme heat, pregnancy, breastfeeding, diet, training, changes in location and other things which is a big change in routine their normal, but only temporarily.