Because of who they are, superheroes of both sexes have toned muscular bodies, sometimes ridiculously so. The sort of bodies that are somewhat in the minority in the world at large., especially the USA.
So, as a photoshop experiment Bulimia.com, a website that offers help and information for people with eating disorders, decided to give them more realistic body types.
They visualized superheroes like Captain America and Wonder Woman with the types of bodies found on the average American man or woman. Making them look a bit more portly than they usually are.
Not sure how that might affect their crime-fighting/super villain slaying abilities, but it's an interesting gimmick nonetheless.
Here's what Bullimia.com wrote:
When it comes to accurate depictions of the human body, comic book heroes are hardly realistic. Whether they’re sprouting blades from their hands or surviving decades in a deep freeze, these characters regularly push the limits of what’s considered possible. But they also depart from realistic human anatomy in a more mundane sense: Almost none of them reflect the typical physique of most Americans.
Today, 33.7% of men and 36.5% of women in the U.S. are considered obese, and more than two-thirds are overweight. Weight gain has put millions of people at risk of heart disease, diabetes, and other preventable conditions. Meanwhile, comic books depict vastly different figures: men with massive biceps and shoulders and women with toned abs and tiny waists.
So what would they look like if they reflected more typical body shapes and sizes? We’ve Photoshopped several major comic book characters – not to touch them up, but to make the average hero look more like the average American.