Here are three related articles about different kinds of body fat, which are almost opposites. Their ratio determines whether we burn fat or store it.
The last article from 2015 shows a change in thinking; “beige fat” is no longer considered a separate type.
How ‘beige’ fat makes the pounds melt away — ScienceDaily August 28, 2012
Researchers from the University of Bonn and the Max Planck Institute of Biochemistry in Martinsried have decoded a signal path that could boost the burning of body fat.
scientists have discovered a signal path in the metabolism of mice that is indeed able to greatly boost combustion inside the rodents’ bodies.
Science distinguishes between three different types of fat:
- White fat is used to store energy and is found in the “problem zones” of overweight people.
- Brown fat cells, however, are used as a kind of heating unit. Unfortunately, adults have hardly any brown fat cells left-except for small areas at the back of their necks and along their spines
- The third category-the so-called “beige fat cells”-are the ones the researchers are betting on. “Just like brown fat cells, they are efficient at converting energy from food into heat, and they can form from the undesirable white fat cells,
the team’s research focused on how to turn the white fat cells into as many beige ones as possible
Pfeifer found that brown fat needs the neurotransmitter “cGMP.” And according to the new findings, this is also true for beige fat. The researchers now studied in mice where cGMP comes from and how it is regulated.
These studies showed that vasodilator-stimulated phosphoprotein (VASP) plays an essential role as a switch on a signal path that slows down the formation of brown and beige fat cells
“This is why mice in which the gene for forming VASP was switched off have the more active brown and beige fat…These animals are lean and dissipate more energy.”
In developing a regulator for the VASP/cGMP signaling pathway, the researchers see a potential starting point for promoting the energy- and fat-burning brown fat cells.
Alexander Pfeifer et al. A VASP/Rac/sGC pathway controls cGMP production in adipocytes. Science Signaling, 2012 DOI: 10.1126/scisignal.2002867
Exposure to cold temperatures can convert white fat tissue from the thighs and belly to beige fat that burns calories for heat, but this biological response is hampered in obese people,
Known as brown adipose tissue (BAT), brown fat is a particular kind of fat tissue that burns energy and glucose to generate heat. Babies and small animals rely on brown fat to stay warm. Brown fat’s energy expenditure helps to prevent obesity in rodents.
While white fat does not share this ability, it can play a role in burning calories when it takes on some brown fat characteristics. The tissue created in this process is called beige fat. When rodents are exposed to cold temperatures, they can convert white fat deposits to beige fat.
“We wanted to investigate whether human adults had the ability to transform some white fat deposits into beige fat when they were exposed to cold,
“Browning fat tissue would be an excellent defense against obesity. It would result in the body burning extra calories rather than converting them into additional fat tissue.”
The analysis revealed belly fat tissue biopsied in the winter had a higher level of two genetic markers for beige fat, compared to the samples taken in the summertime.
In the thigh tissue samples, researchers found elevated levels of three genetic markers tied to beige or brown fat in samples taken during the winter.
The analysis revealed that the seasonal effect of fat browning was blunted in obese people.
“Our findings indicate inflammation can hinder the conversion of white to beige fat,
“When we analyzed tissue samples in the lab, we found that exposing white fat to macrophage cells from the immune system inhibited the transformation.”
Philip A. Kern, Brian S. Finlin, Beibei Zhu, Neda Rasouli, Robert E. McGehee, Philip M. Westgate, Esther E. Dupont-Versteegden. The Effects of Temperature and Seasons on Subcutaneous White Adipose Tissue in Humans: Evidence for Thermogenic Gene Induction. The Journal of Clinical Endocrinology & Metabolism, 2014; jc.2014-2440 DOI: 10.1210/jc.2014-2440
For the first time, a research team, led by a UC San Francisco biologist, has isolated energy-burning “beige” fat from adult humans, which is known to be able to convert unhealthy white fat into healthy brown fat. The scientists also found new genetic markers of this beige fat
The finding was published online on March 16, 2015 in Nature Medicine.
All mammals, including humans, have two types of fat with completely opposite functions:
- white, which stores energy and is linked with diabetes and obesity
- brown, which produces heat by burning energy and is associated with leanness
adult humans also have significant amounts of brown fat.
But until now, it had not been known whether this fat is the so-called classical brown fat of the type that babies are born with, or beige fat, which is found within white fat and has the ability to convert, or recruit, white fat into brown fat in response to cold or other stresses.
they concluded that they had successfully isolated recruitable brown fat.
“We are trying to learn how to convert white fat into brown fat, and until now, it had not been demonstrated that this recruitable form of brown fat is actually present in humans.”
Now that they have a reliable human beige fat cell culture system, Kajimura said, his team will be able to use the system as a screening platform to identify and test small molecules that activate the development, differentiation, and thermogenic (heat-producing) activity of human brown fat
The ultimate aim, he said, is the creation of drugs to turn white fat into brown fat through brown fat recruitment
“If you think about obesity, it’s generally caused by an imbalance between energy intake and energy expenditure,” Kajimura said. ” If we have a compound that increases energy expenditure by recruiting new brown fat and activating brown fat thermogenesis, then it might work synergistically with conventional anti-obesity medications. This would be a novel approach to modulating whole-body energy balance.”
Kosaku Shinoda, Ineke H N Luijten, Yutaka Hasegawa, Haemin Hong, Si B Sonne, Miae Kim, Ruidan Xue, Maria Chondronikola, Aaron M Cypess, Yu-Hua Tseng, Jan Nedergaard, Labros S Sidossis, Shingo Kajimura. Genetic and functional characterization of clonally derived adult human brown adipocytes. Nature Medicine, 2015; DOI: 10.1038/nm.3819