What it doesn't boil down to is, "It's not possible because x, y, z". Or, "There's a reason beyond my control that I can't lose weight".
I'd say it does include "There's a reason that isn't apparent", though.
People, especially here, just insist you need to stop intaking calories and that will lose you weight... simple as, magic wand, job done.
Well what Chrcoluk didn't mention is that when you drop your calorie intake, as well as metabolism slowing, your body also starts restricting the amount of exercise you can manage - You get hangry, you begin to crash, you sleep more, you have less motivation, your mental functions slow, your physical performance drops, and several other things in order to conserve that energy store. That results in a much
lower rate of weight loss so for weeks it will
seem as if they're not losing anything, by which time most people will have concluded that the diet doesn't work and have given up on it.
I didn't eat (except for 40g protein in a shake each day with no carbs) for a week to see what happened lost about 3lb iirc.
I spent over a month, during which
I ate no more than 350kcal and drank between 300 and 400kcal, and lost nothing.
I had to drop the food to 115kcal and the coffee to 250 before I started experiencing any loss, and even then it took almost 3 weeks before anything was noticable.
But of course the odds are I'm just lying...