I remember watching a programme on tv ages ago when they experimented with making veg filling along with more water as part of a lower calorie (but not the extreme lows of a 800 cals per day)) normal diet.
Anyway,they had a weight of mixed veg, plus a certain amount of water. The people who ate the veg and drank the water as two separate entities were hungry again almost immediately.
However, turn the veg into soup with the water, and you're filled up for much longer, and more satisfied, and therefore less tempted to over-eat on the bad stuff.
The analogy they used was a sieve to be like a stomach - stick the veg, chopped up, in a sieve and pour the water on the top - the water goes straight through and is lost. But blend the veg with the water as a soup, and it takes much longer to drip through the sieve, and therefore leaves the sieve (stomach!) satisfied for longer, and then you're less prone to overeating on crap and carbs.
I've never forgotten that programme, and it made a whole load of sense all of a sudden!
The other rule we follow is half the plate has to be veggies/crunchy salad stuff (like peppers, cucumber, carrots etc, not just lettuce). I lost 4 stone making these two simple switches - and I love my carbs and my food! And I've kept it off several years later because it re-educated my stomach about what to expect 
(But still enjoy a take-away once a week - life is for living, after all!)