Other than eating the things and using distractions or distress management skills to help calm yourself down afterwards so you can prove to yourself that it's not horrible....
One thing I can think of is just to try challenging the thoughts you have when they come up? There's a couple of ways that come to mind that you can try, depending on what you think might work best for you?
One is to kind of, accept the thoughts as they come? That means acknowledging them without judgement. Like, okay thanks for that brain. And then just do things like, okay that was a thought, that's not a helpful thought, I'm going to ignore it and move on type of thing. Sort of taking it purely as face value. You could have a google for cognitive defusion and a ton of different ways to do this come up - things like singing the thought to a song, or repeating it out loud over and over, etc. Basically just taking the thought as it is and then working through in your head to wear it essentially doesn't have such a hold on you.
The other is to challenge the thought itself as it comes up with alternatives. Things like, all foods are healthy in moderation, one portion won't make me gain weight, other types of things like that.
Personally I prefer the cognitive defusion type of thing, as I tend to get hung up on judgements. For me that means also that I'm not as worried about how to handle thoughts as they come up, as it's more about acknowledging and validating the thoughts you have, but at the same time holding space for the fact that they're not always accurate/things worth putting value in. If that makes any sense?