Brown fat is one of two types of fat found in humans. Its main function is to generate body heat by burning calories (opposed to white fat, which is a result of storing excess calories).
Which means people with a lower body mass index (BMI) therefore have a higher amount of brown fat.
"Brown fat works in a different way to other fat in your body and produces heat by burning sugar and fat, often in response to cold," said Professor Michael Symonds, from the School of Medicine at the University of Nottingham, who co-directed the research.
"Increasing its activity improves blood sugar control as well as improving blood lipid levels and the extra calories burnt help with weight loss."
No one has found an acceptable way to stimulate its activity in humans - until now.
The research team found that after drinking coffee, the brown fat in people's necks became hotter.
“The results were positive and we now need to ascertain that caffeine as one of the ingredients in the coffee is acting as the stimulus or if there’s another component helping with the activation of brown fat," the Professor continued.
"We are currently looking at caffeine supplements to test whether the effect is similar."
Until then, the study is just one more reason to enjoy a morning coffee break.