Did you know that humans have two kinds of fat cells – white and brown fat? I didn’t until a few days ago while researching topics for my next blog post.
What is brown fat? How is it connected to obesity?
Brown fat or brown adipose tissue (BAT) is found in areas of the neck and shoulders. Colloquially called the “good fat”, BAT is found in high amount in human newborns and hibernating mammals. It is brown in colour, as the name suggests, due to the presence of high amount of iron-rich mitochondria in the cells.
BAT produces heat in the body when the external temperature is low, without shivering, by a process called thermogenesis. That is why newborns do not shiver like older humans. During thermogenesis, the brown fat also burns calories.
Scientists previously believed that BAT was found in humans only in the newborn phase and was depleted in adult phase. However, a positron-emission tomography scan shows the presence of brown fat in adults, though in lesser quantity than infants.
Experiments have revealed that, addition of brown fat to mice increased their energy-burning rate, reduced the amount of fat on their bodies and at the same time protected them from diet-induced obesity. Thus, brown fat is now being regarded as a treatment for obesity, a major health concern in our modern society. A lean person is found to have higher amount of brown fat than an obese person.
How does coffee help?
A study, published in the journal Scientific Reports, in June 2019, found that a cup of coffee can have an effect directly on the function of brown adipose tissues. The scientists used caffeine present in coffee in stem cells to find that a right dose of caffeine stimulates brown fat cells.
Currently, they are looking at whether caffeine supplements produce similar results. This will determine if caffeine is the main stimulator of brown fat or is there any other substance in coffee that also contributes in doing so.