As someone who was overweight for a while and then finally lost enough weight to get to nominal normal... it doesn't matter what is motivating or demotivating you. 1) Obesity is a fundamentally unhealthy state. 2) Either you have habits that contribute to your obesity or you have habits that contribute to being a healthy weight.
If you are obese and want that to change, you have to fundamentally change various aspects of how you live your life (and I realize I'm scratching the surface of a complex topic in saying that, but it's true). That is not easy, especially in today's sedentary, instant-gratification society, and that's why the obesity rate keeps climbing.
Shame is also a choice. Shaming is a misnomer. A person has to choose to feel shame. You can "shame" someone all you want, but if the target has decided not to feel shame, tough luck. Shame is honestly only one person's fault, and that's whoever has chosen to feel it.
Fat acceptance is akin to saying I should embrace a heroin addict's heroin addiction instead of asking them to change.