It's not dissimilar from my son eating a paleo breakfast and dinner at home then having school lunch with the option to choose pasta every day and jelly with a biscuit for pudding. I don't think too much about it, i just try to educate him about food and hope that he'll eventually make better choices when i'm not around.
My kidlets' dad is a cheap and easy kind of guy. Pizza, sandwiches, candy etc. I am going to put it to him this way. "Girl had ADD. Her councilor recommended cutting out food dyes. I also cut out wheat as that is a big ADD trigger. It has made a huge difference so I recommend no wheat/food dyes for the kids. You can feed them what you want but girl is calmer and quieter and better behaved."
Kids learn very quickly about the difference between mom's house and dad's house. Stand your ground and they won't fight you.
I don't think you can go wrong eating whole foods. What's your alternative? Feed them junk 100%?
Unless you are scooping out cups of coconut oil as a side to bacon for dinner, I doubt the increased fat is a big deal. I feel like if the meal you are giving them is some combo of meat, veggies, fruits and stuff like sweet potatos, you can't go wrong. :)