We’ve all done it before – wasting time and effort on pointless tasks just to look busy when the boss walks by. But now scientists have discovered a new type of fat cell in the body that does the same thing, burning energy and generating heat through pointless distractions.
Fat comes in a few different types. The stuff that accumulates around our abdomen and thighs is mostly made up of white fat cells, which act as energy reserves. Brown fat cells are shorter-lived, actively burning their stored energy to release heat and help maintain body temperature. And then there are beige fat cells, which are a mix of the two and do both jobs, but are less efficient than their specialized counterparts.
And now, scientists have discovered a new type of fat cell. It's a subtype of beige fat cell, but it appears to burn energy and generate heat by a completely different mechanism.
Brown fat cells and the previously known type of beige fat cells both generate heat using a protein called UCP1. This protein is found in the inner membrane of mitochondria, the energy-producing components of cells. As part of their normal function, mitochondria pump protons into the space between their inner and outer membranes and then back into the mitochondria. The UCP1 protein creates very narrow gaps in the inner membrane, and as protons pass through them, they create a lot of friction and, as a result, heat.
But scientists began to notice that some beige fat cells lacked UCP1. So for the new study, a team from ETH Zurich investigated how they could generate heat without UCP1. They discovered that the new beige fat cells engage in “empty loops” – biochemical processes that appear to have no specific purpose.
These futile cycles occurred in two ways. In one, cells broke down fats into fatty acids, then quickly reassembled them into new fats. In another, creatine was converted into another molecule called creatine phosphate, which was then immediately converted back into creatine.
Both processes consume energy and produce heat, providing no other benefit to the cell – except perhaps to burn excess energy. is period. It can be like running on a treadmill, it may not actually take you anywhere new but it can help you lose weight.
These new beige fat cells were first identified in mice, but when the researchers examined human fat tissue samples, they saw them there too. Interestingly, they appear to be more common than the previously known type: empty-loop beige fat cells appear to be present in nearly all people, while less than half the population has UCP1 beige fat cells.
As you might expect, people with more beige fat cells of both types appear to be healthier overall. The new study could lead to drugs that help activate these cells or convert white fat cells into beige ones—an area that's been getting a lot of attention lately.
The research was published in the journal Cell Metabolism.
Source: ETH Zurich