So my sheltie needs to loose some weight and after reading different things I'm confused if to use diet foods or it is also ok to feed 'normal' food just give her 15 to 10% less kibble. I don't know if it is good to have a dog on diet food all her life. Right now she is eating N&D weight management. Also I don't know if it is better to use grain free food or low gran or what. If someone can help me in this I would be grateful.