I'm pretty sure a lot of factors are there that need to be examined. Mental issues, control factor, self discipline, genetics, family or friendly environment, playing sports/not, nutritional education, Heavy people have to do twice the work skinny people do to loose weight, as skinny people have to do twice the eating to gain weight like a heavier person...
In my family, my older brother always had a good metabolism so along with sports he was fit until he started parenthood, which he is still in decent shape. My older sister has pretty much been obese her whole life, she did track and field throughout high-school and college shot put and discus, and shes still heavy till this day. Me I'm taller then my older brother and sister and I was baby chubby/not obese, but my metabo and sports pretty much formed my currently fit body today. This is where I get my observable evidence that genetics does play a role in obesity. My brother and I got the luck of the draw, and since heavy set women run rampant on my fathers side, my sister picked up that genetic platform IMO.. Both of my parents were toothpicks when younger, then transformed into older averagely weighed parents...
Like everything in life I believe in relativity, so you have bone skinny and garbage dumpster fat and everything in between, but i'm not to ignorant to know that soceity formation does have a role of the populations health, america runs on unhealthy processed food, and its like you have to go underground to get to the healthy lifestyle here...
Truth is everyone can do something about their situation if they can understand the power of Will and create a proven formula for themselves. But the reality is, life is way to complicated and filled with heavy fog and pathways that obstruct mental ability.life changes. Family deaths, higher education, relationships, pain, ignorance in society, denial, oppersion, bigger issues, work plus excuse plus no time, attaching others ideologies to their own without thinking for themselves etc.....
Like trying to tell a hood dude that selling and killing isnt the only way to live llfe, all they're thinking is I have to eat < It's obvious to you, but their mental perception on the situation is skewed
You get the point, We all know healthy eating and exercise is the solution, but it's just simply not that simple...