Focused mental activity, like sitting at a computer all day or studying, can mean hunger will soon follow. Feeling fatigued, the brain senses it needs more energy if it’s to keep functioning. It’s a built-in survival mechanism.
But it may also play a role in weight gain, as suggested by a new study in Medicine and Science in Sports and Exercise.
According to a press release on Science Daily,
“The modern work environment is highly sedentary and cognitively demanding,” said William Neumeier, Ph.D., lead author of the study. “Previous studies have shown that mentally demanding tasks, such as a big test, grant deadlines or other mentally strenuous tasks we perform every day, affect the brain’s energy demands, and increases in food intake were observed following such tasks. In this study, we explore whether glucose and lactate produced through exercise could serve as a way to provide additional energy for brain function, instead of food consumption.”
It was a small study, to be sure – 38 college students, divided into two groups. One was assigned mental work – completing a graduate level entrance exam – followed by 15 minutes of rest. The other was assigned the same mental work followed by 15 minutes of high intensity interval training on a treadmill. All participants also had a 35 minute session of relaxation one week before the testing to serve as a baseline.
Each session ended with an unlimited pizza lunch.
Those who took the exam and then rested for 15 minutes ate an average of 100 calories more than when they simply relaxed without performing mental work, which reinforces previous studies that suggest working our brains does expend energy and causes feelings of hunger. Participants who exercised after the exam ate 25 calories less than when they simply relaxed for 35 minutes and then ate.
The caloric difference could mean another 23 pounds a year for the non-exercise group.
While this is a small study and more research is needed, the results indicate that breaking a sweat may weaken hunger’s messaging and prevent weight gain. It appears to add yet another reason, in a growing list of many, to incorporate exercise into your day.
Image by Jessica Cross, via Flickr