Building and burning: how synthesizing and catabolizing fats may be keeping you warm

Mammals are warm blooded, meaning that we keep our internal temperature high via a process called thermogenesis. While you might think of moving your muscles or shivering as what keeps you warm, you might not think about brown and beige fat. Unlike white fat, which primarily stores nutrients as fat, brown and beige fat metabolize them, converting that energy into heat. Recently, a team of researchers described a brand new mechanism explaining how. 

Liu and their team showed that certain peroxisomal genes increased in mice undergoing thermogenesis after being placed in a cold environment. Peroxisomes are essential for burning specific types of fats. Here, the peroxisomes are not only burning a special fat – they are making it. The fat cells transfer amino acids to the peroxisomes, build them into a unique type of fat, then break them back down. This cycle was shown to increase the temperature inside of the fat cells themselves, and mice with hyperactivity of this process didn’t gain weight when on a diet that induces obesity in normal mice. While having your cells build fats just to break them down again sounds futile, the energy used results in the thermogenesis necessary for supporting mammalian life.

In these mice, activating thermogenesis was great for preventing diet-induced obesity; however, the prospects for developing a human therapy around brown fat thermogenesis are hotly debated. Humans have far less brown fat proportionally than rodents, meaning that this system may not be as good at preventing weight gain in humans. But some believe that increasing humans’ brown fat stores may be the key to a new avenue to improve metabolic health. 

This study was led by Xuejing Liu, a researcher from the Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA. 

Managing Correspondent: Samuel Lapp

Press Article: “A hidden “backup heater” that helps burn fat and boost metabolism” (Science Daily)

Original Journal Article: “Peroxisomal metabolism of branched fatty acids regulates energy homeostasis”  (Nature) 

Image Credit: Pixabay