First of all, I'm not obese. Second, you lack reading comprehension. Third, you come across as a judgmental and unpleasant person.

It's obviously possible to lose weight with diet and exercise.

It is completely useless (scientifically) for a doctor to say, "Go exercise and lose weight." Same for other similar things, like weight loss and nutrition education. It's been proven over and over again in scientific literature that it doesn't affect outcomes at scale, every trial shows the same thing.

People know that they should eat less and exercise, saying it is not the issue.