I think it goes back to bad lifestyle habits too though. I had cousins that were raised on unhealthy eating. So for them to change, their diet had to change, they had to educate themselves on new healthier food, they had to start denying food that they've eaten all of their lives, and most of all, they had to outright reject a part of their upbringing. We as humans can't just change our mindset on a dime, it takes time, initiative, and the right resources to start taking action. Also, it doesn't help when temptation is everywhere. I had friends that had literally work on their weight FOR YEARS. All this "all it takes is a little exercise and diet change" is short-sighted. It's a COMPLETE 90 degree turn-around for certain folks. On top of that, they patiently waiting to shed pounds little by little. It take self-control, dedication, and patience that a lot of people don't have in them, not to mention the constant ridicule by the general public. Like for me, I can go into the gym or a walk in a calm demeanor, while for people that are overweight, they have to constantly worry about their image, which in turn effects their psyche and may contribute to them discourage altogether.
If you're obese or conquered obesity, you can give proper insight and speak your knowledge. But for those of us that grew up eating healthy and had people look out for our eating habits, we should consider ourselves fortunate and we should be more sympathetic to those who grew up eating bad and had no control the food provided to them. To solve the problem, we have completely understand the circumstances first, then we create solutions.