Meg, I could just take your post and paste it here and call it my own. That is my experience of hunger as well. For me, hunger is the same as the need to breathe, an autonomic drive we can't control or stop. And unfortunately, my hunger is larger than most other people's hungers.
I firmly believe that the only reason I've been successful at losing and keeping the weight off for these past three years is that I low-carb. It wasn't until I started Atkins and cut out most of the non-vegetable carbs from my diet that I ever experienced what hunger must be like for normal people. I must be insulin resistant or have a stronger reaction to blood sugar & insulin than most people because as soon as I started eating in a way to keep my blood sugar stable, I stopped being ravenously hungry 24/7. I could eat and forget about food for a few hours. It was a revelation.
I still eat pretty low-carb today, lots of vegetables and some whole grains, very, very few starchy vegetables and only the occasional refined carb & sugar as a treat. And if I string two or more treats too close together, I immediately start to crave all the old foods again, muffins, breads, cookies, etc, etc, and my hunger is constant and gnawing. It's white knuckle willpower to go back to eating my lean protein & vegetables until my blood sugar calms down again and I get back to normal.
For me the drive to eat is definitely biological. Not to say there isn't an environmental element, there obviously is. I think that's what I see most from these discussions and this book, we seem to have hit a *special* time in history, where our food supply, at least in the wealthier nations of the world, has become so refined and processed that it's almost impossible not to get fat on it. It's not that genetics have changed or we are any more predisposed to obesity than we have been in other times, it's just that we live in an environment that is just perfect for triggering that obesity.
My hunger off switch just doesn't work if I eat Twinkies & McDonalds, but if I have a stir fry of chicken and non-starchy vegetables in a non-sugary sauce, it works just fine.