It's not that far off. If you're not looking at calories in and calories out first, you'll be disappointed. Thermodynamics doesn't cease to operate inside the human body.

Sure, if you're tracking your food intake closely, maintaining a significant deficit, and not losing weight, talk to a doctor about your thyroid. If you're putting in hours in the gym and eating a lot and not gaining any muscle, talk to your doctor about your testosterone level. But if you're looking to hormones and whatnot first, you're probably just deluding yourself.

Are you suggesting that lowering daily caloric intake to 0 would not result in weight loss? Why bother eating then?