Keep it off! Is CLA the magic bullet to keep fat at bay? Find out if this supplement can stop dieter's rebound - conjugated linoleic acid

Ever think you'd hear someone suggest fighting fat with fat? It's true:

Scientists believe a cancer-fighting fatty acid called conjugated linoleic acid (CLA) not only prevents you from getting fat but helps you keep bodyfat off once you've dieted or exercised it away. An increasingly popular dietary supplement, CIA consistently reduces fat gain in rodents, pigs and dogs while fighting breast cancer and other ailments in a number of laboratory studies. It may do little to shrink existing fat cells, but it does stop new fat from getting in, and this phenomenon can be used to your advantage once you've successfully lost weight. But wait, there's more: CIA also has possible muscle- and strength-building effects in athletes, which may be useful for women who play competitive sports.

Fat Blaster

Although CLA is now being recognized as a fat-fighter, the substance itself isn't new Some CLA is probably already present in your diet, especially in dairy foods and beef products, because the compound is made by bacteria in the stomachs of these animals. Even so, most people don't get much more than 100 mg daily in their diet, which is much less than what scientists have found to be optimal. As a result, taking CLA as a supplement looks better and better with almost every study published.

CIA is also produced in small amounts by your body whenever you do intense training, such as high-intensity bodybuilding movements. While it's often found in products that are high in saturated fat, CIA itself appears to be very healthy and beneficial.

The supplement is often marketed for fat loss, partly due to a small number of successful human trials. One study tested 4.2 grams of CIA per day for four weeks on a group of 14 middle-aged men, each of whom had considerable abdominal obesity The supplement caused a significant fat-loss effect. Another study on 16 overweight and obese volunteers found that 3.4 grams of CIA daily successfully improved the amount of fat the subjects lost over 12 weeks of dieting. Interestingly, no improvement was seen at doses larger than 3.4 grams per day, which suggests that 3-4 grams per day would be sufficient if you want to give CLA a try.

Other CLA studies have failed to show a fat-loss effect. For example, 17 healthy adult women who tool( 3 grams per day for more than two months showed no changes in appetite or bodyfat mass. That's odd when you consider how positive the animal research on CLA has been: Pigs, dogs and mice taking CLA consistently gain less bodyfat as they mature.

Lonnie Lowery, PhD, an adjunct faculty member at Kent State University in Ohio, explains: "There is a striking difference between the effectiveness of CLA in animal models vs. humans. For example, mice treated with CLA usually end up being leaner, but I haven't noticed any fat-loss effect in the lean young men I've studied, even with doses as high as 9 grams for 4-6 weeks [no changes in simple skinfold caliper or electrical impedance measurements]. It might be different in women due to the possible effect of CLA on estrogen responsiveness or some other effect, but it's too soon to say.

CLA researcher Mark E. Cook, PhD, professor in the department of nutritional sciences at the University of Wisconsin at Madison, agrees. "A couple of laboratories have been able to find a fat-loss effect for CLA in humans, but only to a modest degree--a couple of pounds over many months, for example."

Fat Loss vs. Fat Rebound

But for other reasons, both Cook and Lowery nonetheless consider CLA to be effective against fat. "Although there is some data on improved 'burning' of bodyfat, recent evidence suggests that CLA works mostly by inhibiting fat-cell filling, meaning it prevents fat cells from getting larger, which is not the same as causing loss of existing bodyfat," Lowery notes. "CLA may therefore turn out to be more useful for preventing fat gain during the holiday season than for causing loss of fat you already have."

Cook concurs: "I wouldn't use CLA for fat loss. I would instead use it to prevent rebound after dieting, for which nothing else really works. For example, CLA was effective at blocking regain of bodyfat in beagles that had been trimmed down on a diet and were then allowed to return to their old eating patterns. The dogs raking a placebo went back to being fat, while the ones taking CLA stayed slim in spite of free access, to food. In general, animals taking CLA gain muscle as opposed to fat."

This suggests that CLA can be very useful in the fight against fat--but only if you use it properly. To best harness CLA's strengths, first lose however much bodyfat you and your doctor or registered dietitian feel is healthy and appropriate for your bodytype, then take 3-4 grams of CLA per day to prevent regaining the fat when you go back to, a less-regimented eating plan.

The rationale behind this method is that it harnesses the ability of CLA to block the filling (or refilling) of fat cells. Cook explains: "CLA works mostly by inhibiting an enzyme on the surface of your fat cells called lipoprotein lipase (LPL) so fat can't get in. Changes in LPL may explain the tendency for people to store more bodyfat as they age, but CLA inhibits LPL and stops this from happening. That probably explains why CLA prevents lab animals from getting fatter as they get older."