 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 and the munitions factories. Chemicals such as dinitrophenol or DNP boost metabolism. So much workers were found somewhere along the road after work covered in sweat with a temperature of 106 degrees Fahrenheit or even 109 before they die, and then even after death their temperatures keep going up like a total body meltdown. At its subacute doses, workers claim to have grown thin to a notable extent after several months working with the chemical. That got some Stanford pharmacologists excited about the promising metabolic applications of DNP. One dose, an arresting metabolic rate jumps up 30% an actual fat-burning drug. People started losing weight and 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 as a weight-reducing remedy that will bring a figure-men-admire and women envy without danger to your health or change 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 by 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 98.6 in our mother's womb straight to room temperature, and we're all wet and slimy. This represents a challenge for thermal regulation for maintaining our warm body temperature. As an adaptive mechanism, the appearance of our 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 it's considered unnecessary, and adults have been considered unnecessary, who have higher metabolic rates, and increased muscle mass for shivering to warm us up if we ever get cold. So we used to think it was just kind of shrink away when we grew up. But if it was 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 scan 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 look 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 fat is present and active. In adults, the more we have, the more active it is, the thinner we are. And we can rapidly activate our fat-burning brown fat by exposure to cold temperatures. For example, 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, and you can elicit a marked increase in energy expenditure thanks to brown fat activation. So hey, these studies point to a potential natural intervention to stimulate energy expenditure, turn down the heat, 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 we'll cover in the next video.