wow people can just not be obese if they fix their habits! what a revelation! Better go tell all the obese people that, they surely have no idea.
Health and age is a factor for some ofc but can you honestly say that people know the nutritional value of what they're eating and also can emotionally control when they eat?
The apparent phenomenon of "free will" emerges from a chaotic, dynamic system, but you must understand the underlying variables if you want to effectively manipulate the result of their interactions.