This is an ad for a shaver. You buy a shaver to shave. You shave because you want to have control over your skin and how much body hair you feel comfortable with. Shaving can make someone feel good about themselves and can be empowering and refreshing, regardless of what other troubles you might have with your body. Self-image is important. Obesity isn't something everyone can fix overnight, and is something that is already part of society and should be be hidden away.Obesity is a disease. We should treat obesity the same way we treat other diseases. We shouldn't shame or insult people who have diseases. But we also shouldn't celebrate disease as a "different body type".
Like the comparison to leprosy is actually apt. I wouldn't point fingers or shame somebody with leprosy. But I wouldn't go "rah rah, you're a leper, and that's okay! You just have a different body type!" That's ridiculous.
This ad is not a celebration of accepting obesity as an ideal, but rather accepting that someone can have good self-image and feel good about a part of themselves regardless of anything else. That is human dignity. I assure you that no one will look at that ad and think "I wanna be fat too!" but maybe someone will look at that ad and think "regardless of anything I might struggle with, I can be happy too because she is happy" and THAT is a win.