It's possible that apples aren't for you, Menzy. I find that apple juice (it's not SBD approved, but I tried something that was apple juice sweetened in my attempts to find some natural sweeteners that might work for me) makes my blood sugar skyrocket faster and harder than even sugar does! But there's a lot of fiber in apples, and they don't affect me at all.
Have you tried eating the apple
with protein, fat, or both (natural peanut butter)? Like Dr. A says in the book, protein, fiber, acid, or fat will help slow down the release of sugar into your bloodstream.
That said, the calories in one apple a day shouldn't cause you to gain a pound...and unless there's something really wrong medically (not that I'm an expert, at all!!!), I'd be surprised that it could lead to a pound gain just because of what it does to your blood sugar. The reason some things don't work for people is usually that they cause cravings which leads to bingeing and all
those extra calories cause weight gain. Did eating the apples lead to bingeing? Are you eating the same as you did in P1 with the exception of the apple and oatmeal?
Are you eating a lot of salt so that you are retaining water?
Sounds like you are working very hard to understand your body, which is great!
Keep at it and I'm sure you'll figure this out.