The Truth About One of the Best Supplements for Weight Loss

A: Conjugated linoleic acid (CLA) has been touted as an effective, stimulant-free weight-loss supplement for more than a decade now, but unfortunately the scientific data doesn't jibe with the sales pitch. CLA is a trans fat that is found in small amounts in dairy foods and almost negligible amounts in grass-fed beef (despite "high levels of CLA" being one of the touted benefits). CLA is actually an umbrella term for several different types of trans fats similar in chemical structure. More research is necessary to tease out which type of CLA is actually the most beneficial (but more on that later).

A lot of the "CLA for weight loss" hype comes from what happens when you feed it to mice-they quickly transform into Mighty Mouse by reducing their body fat by as much as 60 percent. Imagine if you could cut your body fat in half just by taking a daily CLA supplement! Don't get too excited. You're not a mouse, so it doesn't work that way. (Okay, so your hopes about the magical CLA fat burner have been crushed. Reach for these fat-burning foods instead.)

Despite very exciting and promising CLA animal studies, CLA pills have come up very short in delivering weight-loss results to humans. A review of eight clinical trials found a great variability in response to a CLA supplement and changes in body fat percentage. CLA dosage ranged from 0.7 grams to 6.8 grams per day. As for body-fat loss, some study participants lost nearly 7.5 pounds while others gained 1 pound of fat. (P.S. Here's how to burn fat naturally.)

The puzzling part is that the amount of CLA ingested did not seem to be related to observed changes in body composition. In other words, taking more CLA did not lead to more weight loss. This might mean that the type of CLA supplement is more important than the amount, as the type of CLA most actively involved in losing fat (the trans-10, cis-12 isomer, for those of you who like the gritty details) is found in the smallest amounts in our diets (less than 10 percent of the CLA in our diets is that particular isomer). Most supplements contain a mixture of the different types of CLA. (ICYMI, this is the difference between plant-based and synthetic supplements.)

More research needs to be done in terms of seeing if specific types of CLA have greater or lesser effects on fat loss. But based on the current findings, despite all the sleek abdominals you see in advertisements, leave CLA pills out of your daily supplement protocol, as it won't help you lose belly fat or any other type of fat. (And steer clear of this weight-loss drug that's making a scary comeback.)