I didn't order it because my body suddenly became leptin resistant and gave me signals to eat again.
Right. It probably doesn't happen suddenly. Nonetheless, it does happen. Appetite dysregulation is a real thing.
It may often be caused by eating too much junk food in the first place, but that doesn't make it any easier to overcome once it occurs.
Very few people do a bunch of mathematical calculations to figure out how many calories they need to eat in order to maintain energy homeostasis, and then weigh all their food and purposely eat exactly that amount. Instead, it's generally a subconscious process. For the most part, people eat when they're hungry and stop when they're full. The problem is that if their hunger signals get out of whack, it screws everything up and the subconscious process can make overeating nearly inevitable.
Most people with a normal body weight avoid overeating not because they have super elite upper-tier will power, but because they naturally feel full when they've had enough to eat, and food becomes unappetizing when they're full. Some fail to realize, however, that it's not like that for everyone. Not everyone feels full when they're supposed to, and maintaining a healthy weight is more challenging for those people.
You say that you've ordered an amazing-looking dessert even though you felt stuffed and your body was screaming stop. How much more often would you do that if you
didn't feel stuffed and your body
wasn't screaming stop?