Many years back when I was still able to eat pretty much what I wanted, I went on a wheat free diet.
I ate rice, popcorn, and oats without counting carbs and the weight STILL fell off.
For me, wheat was the culprit. Potatoes also give me trouble but by far, wheat is the worst.
And no, I do not have celiac. Been tested for it about 5 different ways and all come back negative. It does not give me common celiac symptoms. But it does cause in me, weight gain.
Interesting observation. Many years ago would have likely been white bread. Have you ever tried some of the recent whole grain breads, especially those made with “ancient grains” like spelt? Cheers