In a way I agree with Winward (bear with me, it has about one million addendums) in that if you take the caloric intake of an obese person, plus the energy expenditure of one, and compare it with that of a so-called "naturally thin" one, they are NOT generally going to match. The "naturally" thin one is likely to eat less, or less often, and/or the average "not naturally thin" person, if they were to shadow them for a week, might barely be able to keep up with them in terms of energy and speed.
However, when it comes to greed - I'm not sure the word sits well with me. There are some metabolic issues - those aside of any medications or medical complications or endocrine system problems, thyroid etc - simply that of how much "lean" mass you have which fuels the fire. But a bigger issue that I do honestly believe you can be born with and is simply luck of the draw is that of appetite, or how your appetite works. Some people naturally do have, and were born with, larger appetites than others. This is evident in babies. Many people will say their children all have different sized appetites. And it is evident in adults. There's always someone who "didn't realise" it was lunchtime in the office and there's always someone who wolfs down their packed lunch at 11:59 on the dot.
True greed may well be the difference between the super morbidly obese and simply those who are a bit overweight, as well as the choices of food they make. But if we forget about the extremes for a minute and focus on the difference between the "naturally thin" types and the "chunky always had to watch it struggle" types - it is almost definitely a difference in appetite. And those people who are size 12 (so curvy but not fat) but have to watch every morsel to stay at that weight, are anything but greedy, they live a life of deprivation. I know this because I am one of them! Apart from when I was pregnant, I've never really "given in" to my appetite, and its vanity alone that stops me being super morbidly obese.
I appreciate that Winward is not talking about people like me who struggle but win, but the super morbidly obese that dont.
One day I might get older and wiser and stop giving a shit. Then what? 