Incorrect. Some people just have no awareness of how much they eat and how many calories they actually expend. Make a food/activity log.
The only common issue with unlosable weight that I know of is thyroid problems, and lazy fatties love throwing that one around.
You can't cheat thermodynamics.
you're half right- caloric balance is key. thing is, even w/out thyroid problems, some people can eat a lot less than others and gain weight while others are losing; everybody's metabolism is different, sometimes drastically so. so fatties still need to eat less to lose weight, but they might be eating a lot less than you think already.
http://www.nejm.org/doi/full/10.1056/NEJM199005243222101