[taneq]

You should spend some of each day feeling at least a bit hungry. If you're not hungry when you sit down for a meal, you've eaten too much already.

There's a huge difference between "a bit hungry" and actually properly hungry. Most people with weight problems probably never let themselves feel more than peckish, and so their perception of hunger adjusts to amplify that feeling. When I'm below my target weight (sitting at a fairly low body fat percentage) and I try to maintain a calorie deficit, the hunger I start feeling is insanely more intense than when I'm a bit chubby and losing weight.