First of all, I think Fitdays activity estimates are probably way off for some of us. By my calculations, I should weigh 82 pounds by now.
So I wouldn't give too much credence to their metabolism stuff. I simply go by the number of calories I eat. 1200ish for me is great, 1500ish and I'm going to have slow, slow weightloss, 1800 and I'm maintaining.
Another thing is, either I build muscle incredibly fast, or else exercise makes me retain water. However, like you said, you gotta believe that the law of thermodynamics is working and I'm not getting calories from air. So eating a number of calories that I know is fine, plus exercise sometimes equals a
weight stall. But... it doesn't equal a size stall.
I REALLY recommend measuring every other week. Its gratifying to see the inches drop, even if the weight doesn't.
Personally, I don't believe that foods cause stalls other than just overeating or perhaps causing water retention. Otherwise, we could just feed the world's poor, undernorished people all the food we claim stalls us and they'd never starve to death, no matter how few calories they got!
Drugs definitely do. Medical conditions do too. Everything else is either just water weight or weight from over eating. IMHO of course. I have as much scientific data to back me up as the people who claim that foods stall them, i.e. none.
I think the real thing to be concerned about foods is whether or not they cause cravings or a glycemic reaction. Or... in my case, whether I can't put the yummy low carb ice cream BACK in the freezer after I've had a serving.