The only way I've ever been able to lose fat is by eating VERY low fat (as in 5-10 grams per day, usually) and low carb (which was also very low calorie). This results in the top half of me looking emaciated, while the bottom half is still chubby. My body would probably rather die than give up that stubborn fat, and no amount of overeating is going to change that.
I think we just have to face that some people are meant to be thin and lean (like SBhike's sister) and some of us are not, no matter what we do or eat. This doesn't mean we still shouldn't strive to eat healthy, but no amount of food/diet manipulation will ever result in looking good for the lucky winners in this group.