"body type" has always been a general term to express the entire shape, size and proportions of a person, including excess weight and obesity.
When I was obese I couldn't pull off crop tops because of my body size, it was incredibly unflattering, and now that I'm a healthy weight I still can't pull off crop tops because of my body proportions, I have a short torso.
Body type encompasses both scenarios, so it's often thought of as a polite way to tell someone something is unflattering without singling out specific "flaws" in their body.
That makes a bit more sense. I was initially reminded of the various pseudo-scientific attempts to classify variations in human body shapes, which usually don't factor in great variations in body fat content. The way it's used in the image made me think this was an attempt to frame an unhealthy lifestyle as something inherent that can't be changed.
I'm aware that any of the past attempts to classify body types are extremely pseudo-scientific and I've explained as much in a different comment in this thread. The point is that "body type" isn't just necessarily just a generic way to refer to someone's body shape. Plenty of people still believe in that made up nonsense.