Nobody is remotely shocked
I don't think anyone is shocked, are they? Most people recognise everyone is different
Perhaps I was OTT in using the word shocked then 
However, below are just some of the comments in this thread alone in response to people who say they'd gain/not lose on 2000 calories:-
*Have you had your thyroid checked?
*If you eat too little you can actually slow your metabolism down
*Well you're talking cobblers to be honest. You've got something wrong with you if you gained 4 stone on 2000 a day.
*I don't think 2000 calories is much.
*The calories don't matter, it is the type of food you are eating. You can maintain / lose weight if your 2000 calories are made up of protein, fat and veg.
*2000 calories is not very much at all.
*Then either you have significant food issues or you don't know how to accurately count calories. Or both.
*i struggle to see how you were eating less than 2000 calories per day and had 4 stone excess. Im not trying to be funny at all, but I dont see how that would happen.
*If you're gaining that much on 2000 then you either can't be of average height or you are incredibly lazy (or maybe a mixture of both)
*Calorie counting is no way to live
*I think the opposite. That 2000 calories isn't much at all.
*If it makes you fat, it could mean you're eating 2,000 kcal of food with high fat and sugar.
*can happily eat 2000+ and still lose weight. If you sit on your arse all day, and do little exercise then this may be different
*It depends how you get the 2000 calories.
*it not that its too much its nowadays people don't consume the right foods with it.its more often not the amount eaten but what is eaten
*All calories are not created equal so counting calories is a completely absurd way of eating.