CLA (conjugated linoleic acid) is a naturally occurring fatty acid, similar to an omega-6 fatty acid but with health benefits for skin and weight loss. It's one of the "good fats," present in foods such as beef and dairy products, but only in low levels. Ironically, beef and dairy products are the same foods that are also high in what we think of as "bad fats," or saturated fats, so obtaining enough CLA through diet alone is problematic.
Also ironically, even though CLA is a fat, studies show that 1.4-3.0 grams per day of CLA will lead to overall body-fat loss.1
And yet, to get that much CLA into your system naturally, you'd have to consume upwards of 2 pounds of beef, a pound of cheese, or 100 ounces of milk every day!
Increased consumption of CLA doesn't have to come from dairy products or beef, however, as the benefits of CLA can be achieved through supplementation.