Except guys the like Sam and Finn and basically anyone else could also have body insecurities. Sam, being so strict about his looks is obsessive and borderline disorderish. Heck, he talked about not eating doritios just to stay “fit” as if a couple would make him fat. THAT ISNT HEALTHY.
And Finn feels insecure about his body compared to the other boys. He was nervous to walk about in his underwear because of it
Regardless of if you wish to see it or not, but guys (or girls) for that matter dont have to be overweight to have insecurities about their bodies. Regardless of it you think he is a hunk or not, it doesnt mean he has to think so. Im sure most would consider Marissa a beautiful and fit female but for a part of her life she obviously didnt hence her eating disorder. Thats an insecurity, thats a disorder and both Sam and Finns behaviors discussed insecurities.