Study finds activating brown fat may protect against obesity

Recent research states that more than 1 billion people around the world have obesity, with scientists projecting that number may hit 4 billion by 2050.

Humans and other mammals have two main types of body fat — white fat and brown fat. White fat serves as the main site for energy storage in the form of triglycerides, found beneath the skin and around internal organs. In contrast, brown fat specializes in thermogenesis, generating heat through uncoupled respiration. Abundant in newborns and hibernating animals, brown fat helps maintain body temperature during cold exposure and is mainly located in specific regions such as the neck and upper back in adults. Both types of adipose tissue play crucial roles in energy balance and metabolism.

For this study, Wilhelm Kornfeld, co-lead author of the current study, and his team focused on a protein called AC3-AT, which they found was responsible for “switching off” brown fat activation. Using a mouse model to test their theory, they found that mice who had AC3-AT removed from their genome were protected from obesity, as their bodies were better at burning calories and their metabolism sped up due to brown fat activation.

“White fat is an organ that stores calories from foods and whose size expands in obesity and causes medical problems. Brown fat stores only little amounts of fat, but in contrast can convert calories from food into heat which is thereby ‘lost’ for the body. Uniquely, activation of brown fat can lead to turning over calories from food which is beneficial in obesity and cardiometabolic diseases. White fat is much less able to do so. In principle, this shows that inactivation of AC3-AT can lead to weight loss (and) improvement of metabolic health in obesity,” said Kornfeld.

Reference: Khani, S., Topel, H., Kardinal, R. et al. Cold-induced expression of a truncated adenylyl cyclase 3 acts as rheostat to brown fat function. Nat Metab (2024). https://doi.org/10.1038/s42255-024-01033-8