[the_omegist]

You should be more measured, that would make your argument more acceptable. You cannot product 10kg of fat from eating 1kg of broccoli...

Moreover : so how ex-obeses who became more "average" do ? A genes therapy? And I am not referring to people who had some surgery but those who could lose tens of kgs.

From another angle : so obese people weighting 200 kg also eat like anyone else, but just have a very inefficient metabolism? NO.

[jjeaff]

Of course not. But one person could eat 10 kg of food and gain 5 lbs, while you eat 10 kg of food and gain 4 lbs all else being equal.

And yes, you can become overweight eating the same thing as someone else simply by having a more efficient metabolism. Unless you believe that there is absolutely no variation between humans, which would be ridiculous. All it takes is a 1% difference in BMR to amount to 25 excess pounds over a year's time all else being equal.