Human beings tend to have the most brown fat as infants, and we lose much of it as we age. But if brown fat has health benefits, is there a way to increase the amount of it we have?
“It is generally understood that an adult cannot actively increase the quantity of brown fat they intrinsically have,” says Maeng. But while brown fat cannot be created, there is some evidence that the brown fat we have can be activated, and that white fat may potentially be oxidized. Again, the research is still in its early stages, but it does appear that certain conditions may activate brown fat by signaling its mitochondria to burn calories and produce heat. Here is what is currently known about how the following factors contribute to brown fat activation:
A review of studies published in Frontiers in Physiology in 2019 examined the effects of certain foods on thermogenesis, the warming process that activates brown fat. The review largely included studies done on rats, but it found that turmeric and curcumin spices, foods with resveratrol (like wine), green tea, and spicy foods with capsaicin may activate thermogenesis and/or trigger fat oxidation, which is the browning of white fat. Further research is warranted to verify the effectiveness of those ingredients on BAT in humans, especially because the dosages required for some (i.e., resveratrol) to see results may be unrealistically high.
Additionally, a review published in Frontiers in Neuroscience in 2021 found that caffeine evokes BAT thermogenesis in rodents, but its effect on human BAT thermogenesis remains unclear. As a registered dietician, Smith doesn’t feel comfortable recommending dietary changes as a surefire way to activate brown fat. “It would be phenomenal if we could,” she says. “But more research is needed before we can offer advice.”
Various past research done in rodents has found particular herbal supplements, including kudzu flower oil, ginseng, quercetin (a plant flavonoid found in many fruits and vegetables), propolis, and oleuropein (a compound found in green olives) to either activate thermogenesis or oxidize white fat in rodents. The results do not directly translate to humans, however, and more research is required. Also, supplements containing these herbs aren’t regulated by the U.S. Food and Drug Administration. So, if you’re interested in giving one a shot, consult your doctor first.
Increasing your workouts won’t create more brown fat out of the blue, but it might oxidize existing white fat into what researchers call beige fat. “There is a correlation between the level of physical activity you do and a better overall distribution of body fat, including the amount of brown fat,” says Maeng. “Managing your overall body fat by working toward healthy weight goals will improve your overall fat distribution. There have been recent studies that demonstrate how exercising switches the body from storing white fat to beige fat, though it is not clear if the beige fat is directly metabolically beneficial or if it is an adaptive response,” she says.
Taking a polar plunge in an ice bath or cryotherapy chamber can activate your brown fat by triggering thermogenesis, according to a study published in the Journal of Obesity in 2018. But Maeng says that taking a brisk walk in the winter may work just as well. “Adjusting your body to cold temperatures by going for a walk outside or taking an occasional cold shower could help,” she adds.
In a small study published in The Journal of Clinical Investigation in 2020, a drug called mirabegron, typically prescribed for bladder control, was given to 14 healthy women to see if it would activate brown fat. Researchers believed it was a possibility because the drug binds to a protein on the surface of cells that’s thought to also stimulate BAT. After four weeks of treatment, the women’s metabolism at rest was almost 6 percent higher, although their weight or overall body composition — the ratio of fat to muscle — hadn’t changed. Brown fat activity, measured by PET scans, also increased during the study. The largest changes were found in women who had less brown fat activity to begin with. Given the extremely small size of the study, those results are not conclusive at all, and another study found the same drug to be ineffective.
Additionally, the study published in Autophagy in 2019 found that the synthetic thyroid hormones thyroxine and triiodothyronine activated brown fat and thermogenesis in mice. Again, human trials are needed to determine any benefit.