What Are Brown Fat Cells and Can They Help You Lose Weight?
The battle against stubborn layers of fat is something most of us struggle with daily. But what if one of the secrets to torching fat was held within the fat itself? Well, brown fat could be the key we are all looking for. But what is brown fat? How is it different from other types of fat, such as white fat (the most predominant variety in the body)? And don’t you want to burn it all away to get a tight torso?
“Brown fat cells are literally brown in color because they contain an enormous amount of mitochondria, which are the power generators of cells,” says Sheila Collins, Ph.D., professor of the Integrative Metabolism Program at Sanford Burnham Prebys Medical Discovery Institute in Orlando, Florida. Isn’t it crazy how fat cells—typically considered just passive storehouses for fuel—contain mitochondria, found in abundance in muscle cells.
Within these mitochondria, brown fat cells burn fatty acids and glucose (sugar) and subsequently produce heat (AKA thermogenesis). So rather than store calories as white fat cells do, brown fat cells actually burn calories while generating heat.
Brown Fat In Babies
Infants have a high amount of brown fat cells since they don’t have the ability to shiver yet, so these heat-producing cells help keep them warm. Want to know why a baby can burn its baby fat so fast? Because as the infant grows into childhood, the amount of brown fat cells gradually declines as there isn’t a need for them since the child is now able to shiver to keep warm.
Where Is Brown Fat In The Body?
Although brown fat cells continue to decline with age, a 2009 study found that most adults still have brown fat cells, albeit in small amounts scattered throughout the body . The cells are most notably surrounding organs, blood vessels, and the spine — and account for up to 20 percent of daily calorie burning.
Brown Fat Vs. White Fat?
Brown fat is different from white fat in a few ways. “Brown fat evolved in warm-blooded animals to protect us from cold temperatures,” says Collins. “Remember, in caveman days we didn’t have houses or clothes, and even following the discovery of how to make fire, you still needed to stay warm enough to survive to live another day.”
Research has not yet proven a way for adults to lose measurable weight with brown fat cells. However, there is hope. A 2014 study — appropriately named the ICEMAN study— brown fat becomes more active in cold weather. The researchers found that chilly temps (about 66 degrees) may even make more brown fat cells grow. “The sensation of cold tells the brain to push the release of adrenaline to the brown fat cells to break down the triglycerides to fatty acids, to take up glucose, and to consume it to make heat,” says Collins.
The takeaway is that colder temperatures speed up the metabolic rate of brown fat cells in humans. If scientists figure out a way to transform white fat into brown fat, we could decrease obesity numbers.
Our old enemy, white fat, rings our bellies and pads our posteriors because it lacks a special protein called an “uncoupling protein,” or UCP1, that allows the mitochondria in brown fat to burn energy uncoupled from ATP production.
Evolutionarily speaking, this fat storage is a good thing since it would help one survive during a famine. But, starvation is not a problem for most Americans. Ever since the Industrial Revolution (roughly 100 years ago), food has been packaged and is cheaply available and in great quantities. Having such easy access to food created a booming obesity epidemic linked to several chronic diseases.
“When white fat cells can no longer find room to continue to stock away these triglycerides [fats], this fat is put into places where it doesn’t belong — such as in the liver or skeletal muscle or the pancreas, where they wreak havoc by becoming toxic metabolites,” says Collins. “Avoiding this abnormal fat storage is critical for avoiding insulin resistance [which can lead to type 2 diabetes], cardiovascular disease, and risk of early death.”
Abnormal fast storage may lead to obesity. Obesity is measured by your body mass index. If your body mass index is over 30 then you are considered obese. If your body mass index is 25-29.9 you’re considered overweight. To calculate your BMI, plug your height and weight into a BMI calculator.
Can You Increase Brown Fat?
Since cold temperature exposure is a trigger, Collins says “there is some interest in trying to slowly adapt people to cool temperatures daily to try to activate and sustain brown fat activity, like wearing a short-sleeved shirt instead of a long one, skipping putting on a sweater, or other simple strategies to keep your body cooler.” (Keep your body cool when you expose your body to cooler temps (around 66 degrees Fahrenheit) for about two hours a day). But, she mentions, it has to be a slow adaptation because before you get to brown fat calorie burning, your body will first start using muscles to create heat by shivering, which is not a very comfortable fat-loss strategy.
Besides the cold, brown fat has also been found to be activated by stress. A small 2016 study in Experimental Physiology found that lean, healthy women subjected to stress had more brown fat activation than when they were just relaxing. The stressor was the anticipation of taking a test, which released the stress hormone cortisol and subsequently activated brown fat cells.
It’s well known that regular exercise increases mitochondrial activity in white fat cells.
What we now know from research is that the calorie-burning function of brown fat cells is activated by adrenaline from cold temperatures and cortisol from stress. While feeling cold and stressed to burn a negligible amount of calories is probably not one’s first choice among all the strategies to lose weight, there is hope.
Collins notes that future research could reveal more about the molecular triggers and pathways that promote brown fat cell activity. Researchers may one day be able to utilize brown fat cells as an effective weight-loss tool. “We’d like to discover how to expand the numbers of these UCP1-containing white fat cells and be able to keep them active at a modest pace,” says Collins. “These UCP1 white fat cells could possibly consume about 250 calories per day above our energy needs to maintain balance — after 365 days of elevated activity that would work out to about an extra 25 pounds of fat burned.” It seems promising, but research is not quite there yet.
Currently, we can’t explicitly target brown fat for weight loss. But strategies to do just that are on the horizon.
A 2018 study from the Technical University of Munich found that whole-body brown fat thermogenesis increased after eating carbohydrate-rich meals, to the same extent as with cold stress. Carb-loading carries with it the risk of storing extra calories as white fat. The risks here seem to greatly outweigh the benefits.
Rather than provide an easy solution, the results of this study suggest that the activation of brown fat could be linked to the feeling of being full, which is an important factor for weight loss (eat things like fruits, veggies, beans, lentils).