I can relate, but in the other direction. Before I started eating healthy I had constant digestive issues, this is probably tmi, but I had lots of gas, cramping, etc. I always thought that's just the way I am. A week or two into eating healthy and it dawned on me, I can't remember the last time I farted. lol I am also a lot more uh consistent. haha
A couple days ago I needed a boost of caffeine so I caved and had a red bull, one of my biggest weaknesses. Never again. The caffeine doesn't bother me, but the sugar crash had me feeling sick, jittery, and weak. By the time I got home I was scrambling for food like a junkie.