What is brown fat and can it help you lose weight?

Fat could mean two things - dietary fat or body fat. By now we knew that there are different types of dietary fats - some good and some bad. But here’s something that might be new - there are also different types of fat cells in the body - white, brown and beige. ‘Brown fat’ has enjoyed attention in the fitness world ever since a series of studies published in 2009 discussed its energy and fat burning capabilities when the body is exposed to cold temperatures. [caption id=“attachment_7318121” align=“alignleft” width=“380”]  Representational image. Image by TeroVesalainen from Pixabay[/caption]

What is brown fat?

Also called ‘brown adipose tissue’, it is found deep in the torso and neck area and is activated in cold conditions. Once activated, it burns ordinary ‘white’ fat and glucose to warm up the body.   Studies in mice have shown that brown fat’s energy-burning capabilities are high considering it is present in small quantities in the body. Current research is focussed on whether these fat-burning capabilities can be harnessed and assist in weight loss programs. So it appears that the enthusiasm surrounding brown fat is a bit premature.  

Can brown fat really lead to weight loss?

For starters, brown fat has extremely low energy expenditure unless it is stimulated (meaning when it’s not terribly cold) and human brown fat has lower energy-burning capabilities when compared to a mouse’s brown adipose tissue. While the body can be trained to produce more brown fat by being exposed to cold temperatures for several hours a day, no study states that this could lead to weight loss. Further, exercising in the cold does not seem to enhance weight-loss programs.   It has been suggested that exercise increases the activity of brown fat but the evidence of this is unclear. Research claims that exercise causes other fat to act more ‘brown-like’, which means that it burns energy to increase metabolism when exposed to the cold. Also, paradoxically, exercise studies have shown that the fat-burning capabilities of brown adipose tissue are actually reduced on exercising. This might be because its primary purpose is to keep us warm and healthy, and not to make us lose excess weight.   While all this information might seem confusing at this point, it’s a part of the process of reaching a conclusive finding. All this suggests is that further research needs to be done on brown fat to make sense of the contradictions.  

Some mysteries unravelled  

A study published in  Nature  in August 2019 shed light on how brown fat helped with metabolism. The men in the study who naturally had higher levels of brown fat activity had reduced levels of BCAAs (branched-chain amino acids) in their blood. While BCAAs carry out vital functions in the body, higher amounts have been linked with obesity and diabetes. Further investigations in mice showed that higher levels of BCAAs did, in fact, progress to obesity and signs of diabetes.

Brown fat may improve metabolism  

Further, an NIH (National Institutes of Health) study published earlier this week showed that a drug that stimulated brown fat activity had favourable metabolic effects in healthy women. The participants were on the drug for four weeks which doubled the amount of brown fat while their body mass remained the same. They were found to have increased resting energy expenditure, higher levels of bile acid which digests fat, higher levels of HDL (which is known as ‘good’ cholesterol) and better regulation of blood glucose. This study only consisted of 14 participants. While there may have been favourable metabolic changes, the participants also experienced increased heart rates and blood pressure which normalized after the drug was stopped. Further, higher doses of the drug (called mirabegron and otherwise used for bladder issues) have been linked with cardiovascular disease.   More research needs to be done on how and if brown fat needs to be harnessed. Until then, the usual adages apply: exercise regularly and follow a healthy diet.   Read our tips on   How to lose weight  for more information. Health articles in Firstpost are written by myUpchar.com, India’s first and biggest resource for verified medical information. At myUpchar, researchers and journalists work with doctors to bring you information on all things health.