A vet tech Clint and I interviewed recently told me she has never seen a dog Marty's age with such good body mass.
Marty has a couple of teeth in the back of her jaw, but that is it. She has to gum her food.
The vet tech was astonished at how good Marty looked. She kept going on and on about how great her body mass is even though she is elderly and has practically no teeth. She asked me how I managed to keep Marty's weight up.
Here's my answer:
When I eat, she eats. She eats whatever I am eating if she likes what I am eating. She usually likes something I have on my plate. I am having soup that does not have any chunks of meat or vegetables she will eat, I will scramble her an egg. If it is something that Marty can't "chew" with her gums, I chew it before I give it to her. It's really that simple. No expensive diets are needed, just mindfulness of her needs.
Marty will "sing" when she knows I am eating chicken. It is her favorite meal.