Junk food hangover

So the best way to describe when I have a cheat meal on the weekend is I feel like utterly CRAP shortly after or the next day! Like the best way I can describe it is like a hangover! I get sluggish, irritable, and bloated, and sick! I felt like it’s gotten way way worse ever since I’ve been eating healthy again. Does anyone know why? I know junk food can upset your stomach, but like I said I didn’t start to feel like that until I started eating better, I’m just more so curious