Resting calorie burn rates matters too. This rate slows as one ages. Building muscle mass increases this rate. And... hormones matter in regards to muscles versus fat storage. Testosterone=muscles, estrogen=fat storage. Fat increases estrogen in both sexes. Women don't menstruate after going below a certain body fat percentage.

There are fat people who really don't eat much but still gain weight. http://www.nytimes.com/2016/05/02/health/biggest-loser-weight-loss.html

Some young redditors here who have "always been skinny" without diet discipline and exercise, when they get older but are still banging down those brews they are going to have a reality check. I say this because some folks here don't understand this concept, they mock and bully (like the OP IMO).

"Take in less calories, lose weight" is an obvious truth that only a mentally challenged person doesn't understand, to say it over and over again and say fat people don't understand this is just more bullying. Why is a thin person so threatened by the mere existence of fat people, that they have to constantly feel superior to them?

FYI, I am not fat, but have battled the beer belly.