Any diet works, if you follow it properly. And following it properly really means re-training habits, I suppose. But for something to work long term you have to be able to eat foods you like.
The egg and grapefruit diet will work, but who wants to eat that for how ever long?!
Eating low carb isn't about just eating red meat, cheese and eggs - that's a massive misinterpretation constantly promulgated by anti-Atkins media/folk. The ideal is that your meals are based around fresh, unprocessed ingredients (meat, fish, eggs or veg, etc) and that your daily carbs come mainly from veg/green salad. With Atkins, the initial 2 weeks, induction period, limits you to 20g of carbs per day, but this is to come from veg/salad. After induction you gradually increase the carbs until you reach the point where you aren't losing/maintaining your weight any more. At this stage you are allowed to include some fruits into your diet.
India Knights/Nerys Thomas diet is also low carb, and has 3 phases. By the time you get to the third phase you can also include some pasta, pulses and bread.
But I do think you're right, (sorry - a long waffle to get to this point!) that for most of us, a diet (any diet) is about training us to eat less. I think we all eat too much.
BTW, I was very impressed with your weight loss - have you kept it off too? That's always the hardest bit!