I have not read the article, but I can relate.
It's not uncommon that people of the same height and weight look very different because of their weight distribution, bone structure, etc.
Take me for example, my coworker and I are both 5'4", somehow I look taller than she(because of my shorter torso). One of my co-worker is petite and full-figured, people often mistake her as much heavier than she actually weighs. So, there you go.