We all know the feeling before a math test: Formulas swarming through your head make your stress levels spike. But that stress could also help keep extra weight off.

A study published recently in the journal Experimental Physiology found that a little bit of mild anxiety can raise levels of the stress hormone cortisol. The cortisol, in turn, stimulates the development of brown fat.

Here’s why some brown fat can be a good thing: While white fat stores excess calories, brown fat generates heat by burning calories. Brown fat’s ability to burn significant amounts of glucose has led scientists to study whether or not it could be a tool in fighting obesity.

To investigate the relationship between psychological stress and brown fat, researchers from the University of Nottingham in England gave a group of healthy women a short math test. A relaxation video was played after the test. To calculate the stress responses, researchers measured the cortisol level in each woman’s saliva. Brown fat activity was then measured to detect skin temperature differences in areas where brown fat is found, usually around the neck.

The results showed that while the math test did not cause stress, the anticipation of being tested did raise cortisol levels. The elevated cortisol levels were linked to more brown fat activity and production of body heat.

Researchers said the study shows the needs for more research on brown fat activity in order to develop better treatments for obesity. They concluded that while extreme stress can exacerbate a poor metabolism, inducing very mild stress could be a solution for overweight patients when used alongside other treatments.