Sadly for most people they go through a cycle of bingeing and then restricting. Or often, as we see every January, Toxing, Detoxing and Retoxing!! If you want to be healthy, and as a byproduct of being healthy, slim. The trick is to eat in a pattern, I've lost count of the various methods I've employed to convince people that crazy diets do not, and will not work. If you aren't taking in enough calories you'll loose two things.
1. The will to live ~ Low calorie is a great way to become depressed.
2. Muscle tissue ~ A restricted diet is great for losing muscle tissue as you slip into starvation mode and begin storing fat. Not exactly the kind of weight loss you had in mind, sure the initial 1/2 a stone looks promising but it never goes any further. By the time you've lost that initial muscle your body has stored fat so while you may continue to loose muscle (if your really dedicated), the scales won't budge and your body will wobble more as the fat piles on.
So, the message, don't starve yourself pre christmas to fit in that little black dress, don't starve over christmas either (equally don't binge, just eat to appetite). Then once Christmas is over, focus on eating regularly and not copying Carol Vorderman on some ridiculous diet. I mean honestly, if she's really so good at math she wouldn't keep squeezing her figure into a dress 2 sizes to small...
Eat, be merry and enjoy food for what it is, essential energy. Do not feel guilty about food, use it as a reward for yourself or punish yourself by missing out.