Please tell if you've changed your diet after being diagnosed.

The problem im having is that everyone is telling me to change my diet and only eat this and not eat that. Ive asked the doctors and they told me i do not have to diet. i know i shouldnt eat fast food, soda, lots of sugar. i dont normally eat that. im trying to eat a well balanced meal but at the same time i dont want to completely cut out everything from my diet. i still wanna have those meals once in a while. or eat that sweet candy once in a while. i wanna have some bacon whenever i want. so what are you guys opinions on this matter. i would really appreciate some feedback.

Edit: Thank you all so much for your feed back! I never been through chemo but I've had two surgerys. One on my hip joint as I had a large tumor on my pelvis. I got a whole hip reconstruction and I was almost amputated from the pelvis. Luckily I had a great doctor able to reconstruct my entire hip with a titanium implant. while preserving my left leg. Almost a year later my cancer metastasized to my liver and I had a hepatectomy to get it removed. i never changed my diet and i dont think i eat bad i eat everything in moderation. but i always have this sweet tooth for candy. and i get soooo MAD when people tell me to eat this and not eat that. like if everyone has a cure for cancer.