I think your sister is fine where she is. Even normal eater children and adults have to say, "hey, this is good, but I'm gonna stop here and have some some other time." That's normal. No dilemma. No angst. Some other types of us like me and your mother just get to a point where a little goes a long way and the food becomes, "ick, nast!" or boredom sets in.
The problem is when people are restricting and banning foods and the food literally haunts them and it's all they can think about. Two reasons: a.) because forbidden fruit is always more tempting, and b.) because usually what they are banning is high fat/sugar/salt and their energy depleted body is screaming for some of that!
When they do give in (and they always will; the body will always be the winner. If it doesn't then you die because you were successful at starvation) they eat like the food is going out of style, and we all know that's not true of McDonalds! Erosion of trust--->restriction--->binge--->guilt--->restrict harder--->binge. And on and on and on.
I think junk food here, gets a really bad wrap. It's painted with a stroke of the devil as if it made anyone do anything. Always a trigger food. Ice cream was mine. Oh that devil food making me get another scoop. There are no trigger foods. There's foods that the body recognizes that will help it make up for the calorie deficit efficiently and so the brain makes them more enticing so we eat them. Again, broccoli, just ain't gonna cut it. For a well-fed normal eater, this isn't even an issue. Once I stopped starving myself, my love/hate relationship with ice cream died.
As for those who just like to plain overeat - well that is a learned behavior to override hunger and fullness and eat just to be eating.
Last edited by bingefree2013; 04-10-2013 at 06:59 PM.