A new study published on 24 June in Scientific Reports, a Nature journal, suggests that drinking coffee may stimulate “brown fat”, the type of fat associated with calorie-burning as opposed to calorie storage. This is the first study of its kind to demonstrate that something as simple as a cup of coffee can stimulate brown fat activity in humans.
Fat tissue is important for storing and releasing fatty acids as well as secreting adipokines, the signalling molecules that communicate fullness and control energy use. However, too much fat can lead to obesity, which is linked to Type 2 diabetes, fatty liver, and other metabolic diseases.
Humans and other mammals have two main types of fat tissue: white adipose tissue (WAT) and brown adipose tissue (BAT). White fat is produced by the body to excess calories. The latter — often simply referred to as brown fat — works in a different way. Instead, generating heat by burning sugar and fat. Brown fat is usually used to generate heat by burning calories and therefore plays a key role in how quickly we burn calories as energy. The fat-burning process is triggered not only by cold temperatures and also by diet.
While brown fat is typically found in babies and hibernating mammals, scientists recently discovered brown fat in adults too. And could possibly help with weight loss by improving blood sugar and blood lipid levels and burning extra calories. But they’re still unsure how to activate this potential weight-loss aid.
Caffeine is known to stimulate the process. So, to find out exactly how much coffee — or more specifically, how much caffeine — is needed, the researchers from the University of Nottingham first looked at the effects of caffeine on stem cells. And once they pinpointed the right dose of caffeine for cells, they focused their attention on humans.
The authors used thermal imaging to determine whether a reasonable amount of caffeine, like the amount in a standard cup of coffee, can directly stimulate brown fat in people. The non-invasive thermal imaging method can detect brown fat reserves in humans based on its ability to produce heat and they discovered that an increase in temperature is correlated with enhanced burning of sugar and fat.
Obesity and diabetes have become major health concerns. In fact, obesity is now a leading preventable cause of death worldwide, and now kills more people than car crashes. In 2016, nearly 40 per cent of adults 18 years of age or over were overweight and 13 per cent were obese, and more than 340 million children and adolescents were overweight or obese, according to the World Health Organisation (WHO).
The results are promising and could provide a novel approach for combating obesity and preventing diabetes. But the authors still need to figure out exactly which components in coffee are responsible for the positive effects on brown fat and whether caffeine is indeed the magic bullet.
(1) Velickovic, K. et al. Caffeine exposure induces browning features in adipose tissue in vitro and in vivo. Scientific Reports (2019). DOI: 10.1038/s41598-019-45540-1