I've written this as a post so as not to hijack/challenge particular members, as that is not my intent.
Focussing on low-calorie foods has some real flaws. Suppose you eat 400 kcals of low-kalorie food for breakfast and you are full, in fact over-full. Yet within a couple of hours, you are hungry again. You can even have that unpleasant feeling of having a full stomach, but being hungry? Then some bright spark comes along and tells you it's because of habit.
Your body is primed to forage for food if you lack certain nutrients, and this is regulated by hormones for instance. Potentially, you could be filling yourself with these low calorie foods six times a day, seldom being truly free from hunger.
Now suppose you eat 500 kcals of satisfying foods for breakfast. By lunch-time you still aren't hungry, and eat 500 kcals of carefully chosen satisfying foods (because you are able to make sensible decisions, not influenced by an insatiable appetite), and similarly with your evening meal.
Which strategy is more likely to result in being able to manage our weight?