Are you just asking overweight people or are you asking all people? The people who are overweight today are obviously the group of people for which social pressure is ineffective. I'm talking about all people including the people who are successfully at a healthy weight.
So even though shame might not work to get fat people to lose weight, it could still work to keep people from ever getting fat. Getting shamed for a few pounds means that you can fix the source of shame by dieting for a few weeks, very doable for average people.
They also gave us insight into the mind of the gay anti-gay politician.
I think it's important to not lose sight of the fact that maintaining a healthy weight is a challenge for nearly everyone and undermine what is currently working for those who are not overweight.
Furthermore, I think obesity has somehow found it's way to be more in line with the LGBT style movements of acceptance/tolerance instead of the changing view of addictions as disease instead of character flaws when it clearly should be much more like the latter.
Educationalist here, actually it isn't :) For many people, this just makes you feel bad - and that's it. For that feeling to result in meaningful action a bunch of conditions have to be met, e.g. the absence of eating disorders (including things like stress eating etc.), a concept of self-efficacy (the idea that one actually is able to change out of one's own will), impulse control, knowledge about food and dieting, the time and money to eat healthier and so on. Often people are perfectly aware that their behaviour is unhealthy, but they lack one or more of those conditions. It therefore is better to focus on providing people the actual means to change (knowledge, methods, better food in school and at work, a supportive environment, taxation to make unhealthy food/drugs more expensive (a thing in the EU)).
Note that I'm fully in support of emphasizing the unhealthy aspects of obesity, though. Providing the facts often just isn't enough.