Focus on the positive part of the statistic, and you could get inspired enough to race to your kitchen to throw out all the doughnuts, sweetened cereals, potato chips, and candy bars in sight. After all, it's certainly motivating to know that last year about 9 million Americans dieted, lost weight, and kept it off.

Focus on the negative part, and you could get depressed enough to race to your kitchen to pig out on all the doughnuts, sweetened cereals, potato chips, and candy bars in sight. After all, it's certainly disheartening to know that last year about 36 million Americans dieted, lost weight, and then gained it - and often more - back again.Focus on the way in which the weight was dropped, however, and you can insure that your next diet makes you a member of the former group and not the latter. After all, success and failure leave clues.And the biggest clue is not new. Like the crux of last week's column, it's an example of what goes around comes around, for once again something associated with the 1980s is making news.Yo-yo dieting. The unfortunate aftermath of losing too much weight too quickly.Let's say too much holiday merry-making has you feeling less than merry and looking more like Santa. You decide to drop those eight pounds you gained by following a diet that guarantees up to 10 pounds of weight loss in only one week.The diet creates weight loss by limiting you to 1000 calories a day. Your body, however, is accustomed to about 2500.After a day or two of receiving 40 percent of its normal amount of energy, your body reacts by going into a type of energy-saving mode. To make up for the lack of ingested energy, your body creates its own by breaking down muscle and using that as a way not - I repeat, not - to burn fat.This response is a holdover from our caveman days when body fat was essential for survival during the colder winter months when food was scarce.After 10 days of dieting, you step on the scale and see what you were hoping to see: your weight before the holidays. The diet did the trick, but never satisfied your hunger. Since you're back to your normal weight, you decide to go back to your normal diet, the same diet you ate before the holiday revelry.But your body is not the same.Because your body catabolized muscle and hoarded fat during the diet that your body interpreted as famine, your body composition has changed. While you're the same weight as before the holidays, you possess less muscle.The muscle you lost required far more energy to sustain itself than the fat you added. So if you resume your former diet, you regain all your former weight.And then some.So guess what you do after the weight gain if you're typical? You diet again. And once again, your target weight is reached by altering your body composition.You've lost more muscle and added more body fat.By now, you may need up to 500 fewer calories per day to maintain your pre-holiday weight. This endless cycle of too-fast weight loss followed by the resumption of a normal eating followed by a "surprising" weight gain followed by another diet is called yo-yo dieting. Back in the 1980s, we knew it produced long-term weight gain.Now we know it helps produce poor long-term health.A few years ago, for instance, yo-yo dieting was linked to an increase in the risk of death from heart disease.More recently, research has added a second reason as to why the yo-yo dieting pattern dooms long-term weight loss. It alters what goes on in your gut.For a few years now, we have known that some of the bacterium in your belly help you maintain a healthy weight and some do not. The key is to eat in a way that increases the former and reduces the latter.Research recently performed by the Weizmann Institute of Science in Israel and published in the journal Nature shows that simulated yo-yo dieting in mice produces the latter and the unwanted weight that comes with it. The weight gain was significant enough so that co-author Eran Elinav and his colleagues found it elevates insulin and triglyceride levels enough to increase the risk of type 2 diabetes.So what you need to do if you have added a few pounds as part of your holiday festivities is avoid yo-yo dieting by using go-slow dieting to drop the unwanted weight.A good rule of thumb is to shoot for about a 500-calorie a day reduction by eating 250 fewer calories a day and increasing the calories you burn through activity by the same amount.This way, your body doesn't go into energy-saving mode. It makes up the deficit by using fat from the fat stores.And that's what you really want, isn't it?