What if I told you that your body fat comes in different colors? And what if I also told you that the fat in one of those colors could actually help you lose weight? Would you think I was crazy?

Well, both those statements are true (and possibly that I’m crazy too – but that’s a separate issue). You may have already heard that there are two types of fat that our bodies can have – white fat and brown fat. The difference between them is not just a matter of color. White fat cells store lipids (fats) and brown fat cells actually burn lipids. So it follows that having more brown fat cells could help control obesity by causing us to use up more energy and  lose weight.

In recent times, it has been found that people of all ages have brown fat cells, which was not known previously. Even more recently, a study in the prestigious journal Science* showed that in genetically-engineered mice, a specific enzyme – known as cyclooxygenase-2 (COX-2) – has an important role in making more brown fat cells in the body. The mice that were genetically-engineered (bred to have certain qualities) to have more of COX-2 in their bodies, and thus more brown fat cells, were 20% lighter in body weight than ordinary mice.

Since the bone and muscle mass of each group of mice were the same, this difference in body weight was completely accounted for by the fact that the mice with more brown fat had less total body fat. And since both groups of mice had the exact same amount of food intake, the lesser amount of body fat was due to the fact that the mice with more brown fat were burning more fat than the others.Even more interesting is the fact that the mice with more brown fat seemed to be protected against gaining weight.  When these same mice were fed a diet with a substance that inhibits the COX-2 enzyme, which them caused them to have less brown fat, they gained weight.

If you’re wondering where you’ve heard of the enzyme in the body that inhibits COX-2, remember that many of the anti-inflammatory drugs known as NSAIDS that are used for joint and muscle pain are COX-2 inhibitors, such as Celebrex.

So, what does that mean for us humans? The new knowledge that the enzyme COX-2 can stimulate the formation of more brown fat will hopefully lead to new medications that will do the  same thing, and thus help us to control weight gain.  And what about the thought that those anti-inflammatory drugs may be causing us to make less brown fat, and thus gain weight? That needs to be studied in humans, especially the doses that may do this. So don’t stop your NSAID pain reliever if it is helping you BUT stay tuned. Oh, and remember that even though it is summer – white is out and brown is in!

* Vegiopoulos A et al. Cyclooxygenase-2 controls energy homeostasis in mice by de novo recruitment of brown adipocytes. Science 2010 May 28; 328:1158.