Someone finally wrote this article. So refreshing. It's obvious when you live with a fat person why they have trouble losing weight, even when they're on a diet: they're usually not actually following it. Whether they don't understand portion sizes for calorie math, or look at calories at all, or eat things that they say "do not count", there is almost always a failure to understand what and how much they are eating.
Even if there was a device that could scan all food before eating it, they would still exempt some meals with the "do not count" argument.
Rule of thumb, that if a meal is easy and fast to prepare, then it is probably not suited for a diet.
To lose weight you have to do a lot more exercise than you think consistently. And you have to eat a lot less than you think.
Most people just don't have that kind of willpower.