My vet recommended against the senior food. One of the main things they cut from it is fat, which can lead to dry itchy skin. She suggested that we just feed a bit less of the regular food and supplement it with some vegetables. That gives him the volume so he's not ravenous, but reduces the calories and increases the vitamins. We found that Sam loves zucchini and carrots. I blanch and dehydrate them. They could easily be frozen but our freezer space is limited.
We feed twice a day and I add his vegetables to his breakfast since fullness from veggies doesn't seem to last quite as long. This way he's got his full, regular evening meal to tide him over the night. I rehydrate and add about a cup to his breakfast and cut the dog food down to about a quarter of his "regular" ration. He's 12 now and has lost enough weight to be really fit and vigorous for his age. If his skin/coat seem dull and dry, I'll add a tablespoon of oil to his food once a day. He has thyroid issues, so we tend to do this quite a lot. I use olive oil since many dogs have problems with corn products.
