For me, it depends a lot on what type of fat it is. I avoid certain types of oils and fats and do my best to get the good ones. Some oils help my gut while others clearly tear it up.
We made a chocolate cake from scratch last night with healthy fats, like organic butter (and coated the baking pan with coconut oil and flour instead of the shortening and flour I grew up using). Because of my blood sugar issues, when I was married, I informed my husband early on that if he wanted homemade sweets from scratch, he could make them himself. I cooked dinner but he did most of the baking of cookies. If I made a cake, it was from a box and it was probably someone's birthday. I only began using organic butter and stuff like that around 3 years or so ago, so my kids have never had anything before like the cake we made last night. The last couple of years, I haven't even had sugar in my home. We have been working on cleaning up our diets and learning what works for us and in recent months we have been working on developing recipes based on what we have learned as far as food chemistry and which ingredients help our guts and which ingredients screw them up royally.
So making the cake was an adventure and from the start I was telling my son that even if we made some mistakes, this would be the best cake he has ever had. He was skeptical. Then we got the unsweetened chocolate and organic butter melted and the smell was so amazingly good, and different from most store-bought sweets. He has a keen sense of smell, so this really made an impression on him. By the time we stuck it in the oven, he was crowing about how this would be THE BEST CAKE EVER!!!! And it was.
We don't do Halloween these days. My sister says I got my dad's Scrooge genes -- I'm just not big on Holidays generally -- and my kids are grown now. But when they were little, I tried to take them to skate parties and things like that if it was available instead of taking them trick or treating, then I would take them to the store the day after Halloween, when all the Halloween candy was half price, and let them each pick out one bag of a favorite goody. As a kid, I really didn't like the fact that I got so much variety of stuff at Halloween because I simply couldn't eat many of the things I got. My kids were happy with that solution. If my son and I had been diagnosed sooner and if I had known then what I know now about food chemistry and how it impacts us, I probably would have made homemade goodies from wholesome ingredients, like the cake I made last night. I know my kids would have been happy to have personalized traditions that didn't upset their stomachs so much.
Good luck with this.