the “when i go on a health kick” would be the problem, you kinda can’t “go on a health kick”, you don’t have a health bar that can be periodically topped up while otherwise eating garbage.
it’s much better to always eat one carrot per meal than to have one meal per week that consists solely of carrots, not only does that give your body a baseline to work with, but it also means you get used to eating that carrot and eventually you start to quite enjoy it, and the thought of not eating a carrot with your meal feels a bit wrong, and adding another carrot to each meal isn’t a very daunting prospect.
I used to subsist basically entirely on fast food, and at this point any meal without some proper vegetables feels somewhat unpalatable. I’ve also just straight up replaced candy with simply eating more food, and candy holds little appeal now. Why suck on a caramel when i can eat a tasty sandwich instead?
You’ve got to slowly ease yourself into a healthy lifestyle, and experiment around to find out what works for you. Maybe you love boiled vegetables, maybe you absolutely hate them but instead crispy fried ones herald the choirs of angels.