It's probably not good for weight loss, but it may be good for keeping lost weight off, with a little warning.
According to a study at the University of Wisconsin:
Dr. Michael Pariza, who conducted research on CLA with the University of Wisconsin-Madison, reported in August 2000 to the American Chemical Society that "It doesn't make a big fat cell get little. What it rather does is keep a little fat cell from getting big."
Pariza's research did not find weight loss in his group of 71 overweight people, but what he did find was that when the dieters stopped dieting, and gained back weight, those taking CLA "were more likely to gain muscle and not fat.'' In a separate study conducted at Purdue University in Indiana, CLA was found to improve insulin levels in about two-thirds of diabetic patients, and moderately reduced the blood glucose level and triglyceride levels.
Other similar studies have had the same results. One study of 180 volunteers showed that volunteers who took 3.4 grams of CLA per day lost 4 pounds over the course of a whole year. That doesn't quite seem worth the effort and the money. However, studies done on people that have already lost the weight showed that those taking CLA during maintenance were less likely to gain back their fat. So the best advice would be to wait until you reach goal to try CLA.
Here's the little warning: It's important to note that there have not been any studies on long term safety. Plus, in the study of the people that lost the 4 pounds over the year, additional tests showed they increased their risks for heart disease because those taking CLA increased their "bad" cholesterol and lowered their "good" cholesterol. And the CLA group had higher white blood cell counts and lipoprotein (a) levels. Both are markers of inflammation linked to heart disease.