Come January 1, most people look back on the last month or so of happy indulgence with a tinge of scale-based regret. Well, there's a new scientific study that offers a no-exercise, no-dieting way to not gain weight over holidays?and maybe stay trimmer all year round.

The study was conducted by researchers at the University of Wisconsin, in Madison, and at the University of Guelph, in Ontario, , and was published recently in the International Journal of Obesity. The researchers investigated conjugated linoleic acid, or CLA, a building block of fat, found mainly in meat and dairy.

The researchers studied 40 healthy but overweight people: 32 women and 8 men, ranging in age from 18 to 44. They divided them into 2 groups. Over six months, one group took a supplement of 3.2 grams of CLA daily and one didn't. The researchers weighed the study participants three times: pre-holiday (August-October), holiday (November-December), and post-holiday (January-February). The results?

The CLA group actually lost a tiny amount of weight during the holidays: about 1/5th of a pound. Meanwhile, the group not taking CLA gained an average of 1.3 pounds. (With many gaining much more.) The non-CLA group also gained a bit post-holidays, while the CLA group stayed stable. Over the six months of the study, the CLA group lost 2.2 pounds, mostly fat, and mostly from the belly.

Maybe you're thinking the non-CLA group simply ate more. Nope. Both groups ate the same amount of calories and got the same amount of physical activity. The only difference between the two was?taking or not taking CLA.

A couple of other interesting points from this study:

The researchers note that pounds put on during the holidays are particularly hard to lose. They also tell us that the heavier you are, the more weight you tend to gain during the holidays: the heaviest folks in the study gained an average of 5 pounds in November and December. So CLA might be particularly helpful over the holidays for those who are 20, 30 or more pounds overweight.

How does CLA work to prevent weight gain? Nobody knows for sure. It may stop fat from getting into fat cells. It may affect the development of new fat cells. It may burn up fatty acids in muscle. But that it does work is a proven fact.

A two-year study published in the American Journal of Clinical Nutrition showed that people who took CLA lost 5 pounds of fat and gained 2 pounds of muscle in about 3 months?and remember, that's without reducing calories or increasing physical activity.

Can you get enough CLA through your diet to lose weight? No, say the experts I've talked with. You'd practically have to live on meat and cheese?and even then you wouldn't get 3.2 grams a day.

I've taken to mentioning CLA supplements to anybody I talk to who wants to effortlessly lose some fat and gain some trimming muscle. (And who doesn't.) People (particularly women) are telling me that they can definitely see the difference after a month or two of intake: a noticeable trimming and slimming, as fat is lost and firming muscle is gained. Usually, women lose about a dress size in 1 to 2 months.

Studies show that CLA is very safe. And it's also good for more than weight-loss. It may play a role in preventing cancer, boosting immunity, and strengthening the circulatory system. And it also has been shown to boost mood, particularly among dieters. The researchers in this study reported that ?negative emotions decreased significantly? among those taking CLA.