Avoid Overeating After Mental Tasks
When you spend time tackling a project that requires a lot of mental energy, you often end up feeling somewhat drained. Putting your brain to work can be exhausting. And unfortunately, it was shown in 2007 study at Laval University in Quebec, Canada that frequently our reaction to a hard mental workout is to eat—a lot.1 But it doesn’t have to be that way. In fact, according to new research, countering the after effects of mental activity with some physical activity may help keep you from overindulging.
The current study, which was conducted at the University of Alabama at Birmingham, found that exercising after a mentally challenging undertaking may prevent the overeating that often follows.2 The subjects were 38 college students who were given a graduate school entrance exam to complete.
To establish a control situation, all of the volunteers had a 35-minute relaxation session the week before the main experiment. During this session they were not allowed to read, have a conversation, or stretch—in other words, all forms of mental and physical activity were avoided. Afterward, they were given a lunch consisting of all-you-can-eat pizza.
The following week at the trial, the participants were randomly separated into two groups. They all took the test, but afterward one group was told to rest for 15 minutes while the other group was asked to perform 15 minutes of high-intensity interval training on a treadmill. When the 15-minute post-exam periods were over, all of the subjects were once again provided with an unlimited pizza lunch.
Calorie counts were measured at these pizza fests, and those who had the rest time after the test consumed an average of 100 calories more than they had after their previous control session in which they relaxed without taking part in a difficult mental task. As mentioned above, this is in line with earlier research findings. The surprise was that the group that had worked out after the test actually consumed 25 fewer calories than they had during their control session and 125 fewer calories than did the group that rested after taking the test.
But why, you might ask, would expending greater amounts of energy through physical activity result in the consumption of fewer calories? Wouldn’t it make the participants even hungrier? The scientists believe the answer may lie in lactate production. Blood glucose levels in the volunteers who worked out remained steady, but their lactate levels skyrocketed. That’s because interval training is a form of anaerobic exercise during its brief bursts of high intensity, which raises lactate production in the muscles. It is possible that this increase in lactate helped replenish the energy stores that their brains had expended on the mental challenges, promoting a faster recovery; but obviously, more research into the effects of both lactate and glucose are needed to determine their effects in this case.
The study was limited to an extent by its very small subject pool and the narrow scope of age included in the population sample. Despite this, it does provide some food for thought (all puns intended). Whatever the exact mechanism behind the results, the idea that exercise can help temper our urge to binge is exciting and promising. In fact, a 2016 study at Loughborough University in the United Kingdom had similar findings, providing evidence that physical activity can quell hunger.3
Ultimately, though, the current study is really just one more piece of evidence that we should all be working out every day. If exercise helps stave off the urge to overeat after a difficult mental activity, that’s great. It might make a case for timing your exercise for after work—that is, if you frequently deal with mental challenges on the job. But even if you don’t, it’s essential to carve out some time each day to devote to physical activity. Aside from helping your body burn more calories and maintain a normal weight, exercise is beneficial for your mental well being and long-term health.
- 1. Chaput, Jean-Philippe and Tremblay, Angelo. "Acute effects of knowledge-based work on feeding behavior and energy intake." Physiology & Behavior. 30 January 2007. Accessed 14 September 2016. http://www.sciencedirect.com/science/article/pii/S0031938406003830.
- 2. Neumeier, William H.; et al. "Exercise Following Mental Work Prevented Overeating." Medicine & Science in Sports & Exercise. September 2016. Accessed 14 September 2016. http://journals.lww.com/acsm-msse/pages/articleviewer.aspx?year=2016&issue=09000&article=00021&type=abstract.
- 3. Alajmi, N.; et al. "Appetite and Energy Intake Responses to Acute Energy Deficits in Females versus Males." Medicine & Science in Sports & Exercise. March 2016. Accessed 15 September 2016. http://www.ncbi.nlm.nih.gov/pubmed/26465216.