Brown fat, first found in infants and small animals, burns calories to generate calories. For a long time, it has been thought that adults do not have brown fat. However, a few years ago, scientists found that some adults still have a small amount of brown fat, while the elderly and obese people have little or no brown fat.
When the temperature drops, the body turns on the expression of a series of genes, generating heat and converting white fat into brown fat, which is the first step in fat tissue [browning]. A recent small study in the human body shows that brown fat increases blood sugar metabolism, insulin sensitivity and energy consumption after slight cold exposure.
Another study found that in abdominal adipose tissue, other genes related to lipolysis and energy utilization (adiponectin, AMPK, HSL and ACC) are also up-regulated in winter, where UCP1 protein level in fat is 3 times higher than that in summer.
However, in people with BMI over 30 Kg/m2, the seasonal upregulation of UCP1 mRNA level is greatly inhibited, suggesting that [white adipose tissue in obese people is dysfunctional and inhibits fat thermogenesis]. The reason is that chronic inflammation has always existed in adipose tissue of obese people, which will block the expression of lipoprotein in adipocytes.
This shows that different populations have different abilities to activate [fat browning gene] after temperature changes, Obesity and inflammation will reduce this [browning reaction]. If obese people cannot produce browning fat like slim people, they may also have difficulty burning fat, resulting in continuous weight gain, fat [loss of metabolic elasticity] and reduced responsiveness to environmental changes.
Finding out how this happens may help the development of obesity drugs. [We have a lot of fat in our bodies. If we can brown some of the white fat, we can produce more calories instead of storing them in the body in the form of adipose tissue, thus preventing obesity.]
Author: Gao Fei