I think the fear of hunger is very interesting. You know you are getting enough food to live well on, you know you are not in a famine situation and where your next meal is coming from, so why not just allow yourself to feel hungry until you get used to the smaller portions? It sounds like a psychological barrier - there is nothing harmful or wrong in feeling hunger, if you know you're getting the right amount of food. We don't have to give in to every impulse that strikes us.
So many people eat out of habit, out of boredom or mindlessly while doing something else, you have to change your behaviour and your mindset before you can change your weight. And QVC can't sell you that in sachets!
it's not a fear just a feeling that most people find unpleasant. if it was so easy to ignore, there would be no overweight people.