Transcript: Brown Fat: Losing Weight Through Thermogenesis
During World War I, it was discovered that many of the chemicals for the new explosives they were working on had toxic, or even lethal, effects on the workers in the munitions factories. Chemicals such as dinitrophenol, or DNP. It boosts metabolism so much, workers were found somewhere along the road after work, covered in sweat, with a temperature of 106º Fahrenheit, or even 109º before they died. And then even after death, their temperatures kept going up, like a total body meltdown. But at subacute doses, workers claimed to have grown thin to a notable extent after working with the chemical for several months.
That got some Stanford pharmacologists excited about the “promising metabolic applications” of DNP. One dose and our resting metabolic rate jumps up 30%—an actual fat-burning drug. People started losing weight with no apparent side effects as a result of their weight-reducing treatment. On the contrary, they felt great - until thousands of people started going blind and users started dropping dead from hyperpyrexia, fatal fever from the heat created by the burning fat. Of course, it continued to be sold. “Here, at last, is a weight-reducing remedy that will bring you a figure men admire and women envy, without danger to your health or change in your regular mode of living. No diet, no exercise!” It did work, but the therapeutic index was razor thin—a razor thin difference between the effective dose and the deadly dose. It was not until thousands suffered irreversible harm that it got pulled from the market. Until, of course, it was brought back to the internet for those dying to be thin.
There is a way our body naturally burns fat to create heat, though. When we’re born, we go from a nice tropical 98.6º in our mother’s womb straight to room temperature, where we’re all wet and slimy. This represents a challenge for thermoregulation—for maintaining our warm body temperature. As an adaptive mechanism, the appearance of a unique organ around 150 million years ago allowed mammals to maintain our high body temperatures.
That unique organ is called brown adipose tissue, or BAT, whose role is to consume fat calories by generating heat in response to cold exposure. The white fat in our bellies stores fat, but the brown fat, located up between our shoulder blades, burns fat.
It’s essential for the thermogenesis, the creation of heat in newborns, but has been considered unnecessary in adults, who have higher metabolic rates and increased muscle mass for shivering to warm us up if we get cold.
So, we used to think it just shrank away when we grew up. But if it were there, then it could potentially make a big difference for how many calories we burn every day—but supposedly we outgrew it.
But when PET scans were invented to detect metabolically active tissues like cancer, oncologists kept finding hot spots in the neck and shoulder regions that on CT scans turned out to be not cancer, just fat. Then, some observant radiologists noticed they appeared in patients mostly during the cold winter months, and when we looked closer at tissue samples taken from people who had undergone neck surgery, we found it: brown fat in adults.
The common message from these studies is that BAT is present and active in adults, and the more we have, the more active it is, and the thinner we are. And we can rapidly activate our fat-burning brown fat by exposure to cold temperatures. For example, if you hang out in a cold room for two hours in your undies and put your legs on a block of ice for four minutes every five minutes, you can elicit a marked increase in energy expenditure, thanks to brown fat activation. So, these studies point to a potential “natural” intervention to stimulate energy expenditure: turn down the heat and burn calories (and reduce your carbon footprint in the process!).
But thankfully, for those of us who would rather not lay our bare legs on blocks of ice, our brown fat can also be activated by some food ingredients… such as those that we’ll cover in the next video.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.
Please consider volunteering to help out on the site.