This is a myth that exercise is enough to lose weight but you need to have a healthy diet as well. Too much exercise as well can have adverse effects ad a person cannot consume cheese, butter or junk food in excess if they are obese. A normal person can eat once a while and not daily.
There's no myth. The only way to lose weight or to remain healthy is eat less and exercise more. You can eat as much as you want as long as you burn it off though a poor diet will have other negative effects on your health in the long run.
I have seen many people who believe that if they exercise a lot, they can eat anything they like and will always remain thin. My own friend who is overweight exercises for almost 5 hours but then has pizzas every weekend which ruins her diet.
It's not necessary to eat less but it's necessary to know what to eat and what to avoid. Too much of oil, cheese, butter and fats cannot be sonsumed and it's better to avoid them rather than to get addicted to these food stuffs.
What if I were to say that whether someone is fat or not is determined by that person's particular configuration within society and that that person has very little say in it? It's akin to elements of nature falling into their respective natural states because of the pressure from everything else around them, like when you fill up a complex shaped glass bottle and the water naturally fits into every nook and cranny. 
