I definitely understand that, which is why the first week of dieting is always the hardest because you're getting your body and your mind used to it. But for me if I eat really unhealthily for a while and I gain weight, my body gets to the point that I feel like shit, and I just stop wanting food, my body wants to starve itself in a weird way and it's breaking the habit that becomes the hard part. There's a mixture, partly that your stomach has stretched to accommodate more food, partly that your body is now used to the sick feeling you get after eating too much and either you enjoy that or you confuse not having that feeling with being hungry, and of course, cravings for the chemicals and additives found in so much unhealthy food. I know for a fact that when I over eat to the point of weight gain I will rarely feel the true feeling of hunger, yet I will "feel" hungry. That is my mind telling me I want to eat, rather than my body telling me I need to eat.
For someone to be overweight and even considerably overweight there could be lots of factors there, genetics, for women perhaps childbirth, the way you're raised or just general greed, lack of self control and feeling like you need to eat more, whether just because or because of some sort of life issue.
For my friend it apparently happened after his mother had a load of problems, since then he has over eaten and gained the weight. It's not a genetic problem, all his family are slim and healthy and he was slim and healthy until his mid/late teens, I do know some people who don't over eat that much but still are very overweight, I for example probably don't eat any differently to most people my age, yet I know many who are far slimmer than me and some who are far bigger than me, for some it is difference of eating, but for a large part it's genetics.
I also know people who've dieted and lost large amounts of weight, no fast process, but over the course of a year or two people can do incredible things, and these people have suffered from no physical problems from losing the weight, their bodies haven't gone into the sorts of problems that comes from a physical addiction.
I still believe it's a mental addiction more than a physical one. Sure, your body gets used to food and enjoys things like salt and fat, and I do think that there is an element of additives being physically addictive, but food itself? I think it's very easy to think that your body is craving something when really it's your mind wanting that thrill/feeling of being full. Someone posted a while ago something about porn addicts, how they continuously want to get that "hit"/"thrill" of watching porn, so they do it again and again and eventually become dependant on it/can't stop. That's undoubtedly a mental addiction, you can't be physically addicted to something that's so purely mental. I don't think eating is all that different. Physical addictions are things like heroin/tobacco which your body depends on to survive, meaning you'll get ill if you stop. Mental addictions are things like crack and cocaine, yet they are two of the most addictive drugs out there. Someone might be addicted to say, crack, and feel lots of physical results when they withdraw from the drug, though it isn't a physically addictive drug. I think... though I'm not entirely sure, that the addiction that over eating causes is very similar to this.
Of course over eating addictions are also very hard to kick because unlike a crackhead could quit completely, an over eater will still have to eat food to live and will be faced with temptations every single day.
I also think food is more addictive than a lot of other things because it's natural. Same as sex. I personally do not seem to have the physical or mental ability to become addicted to things, except for food and sex. In fact, everyone to a point has a food and a sex addiction, just for some people the cravings are either harder to say no to or food has a different effect for some.
I know America has "fat camps", which when I was younger I thought sounded super harsh, but really, I think they're a brilliant idea! I mean maybe not by being called fat camps, but some form of rehab centre where a person can spend 6 months to a year sorting their eating patterns out, learning to say no to every day situations, getting used to eating the foods they enjoy, but in moderation and using healthier ingredients to make certain foods, getting introduced to daily exercise in a place that they don't feel like they're going to be judged. This sort of thing, having a boost into weight loss, sure you'd have to take time and money out of your life to do it, but it could improve your quality of life and general living by so much. Jesus, I'd do it! I'd love to be able to go and live somewhere for a few months and do loads of training and healthy eating, getting my body the way I want it to, sure, maybe I'd gain weight again, but I'd still do it. Sometimes with dieting all you really need is a good kick start and a bunch of support to show you just how well you can do.