We've been feeding the dog "human food" (chicken, rice, sweet potatoes, and spinach) mixed in with her kibble for a few months now, with definite success. She has gained back almost three pounds and is much more enthusiastic about her daily meals.
But roughly every 10 days or so she disdains her meal, even though she acts like she wants it. She pokes and nibbles at it for a few moments, then walks away. She'll usually come back to it a bit later and do the same thing again without really consuming any substantial amount of it. We have no idea why. We know she's hungry, and we know she likes what we're feeding her.
We tend to project our thoughts onto our pets because they can't express themselves to us in a way we can understand, so I find myself thinking things like: she's refusing to eat on purpose just to be difficult. Her unpredictability is what's perplexing to us because dogs tend to prefer very regular feeding patterns. But it is possible there are times when she just doesn't feel like
eating, and given her advanced age that's probably what's happening. I also know that a couple of hours from now she'll be hungry, and will expect me to prepare her a fresh meal.