It’s impossible to miss all the news about the obesity epidemic that is sweeping industrialized nations around the globe.  We’ve become accustomed to hearing that a lack of regular, strenuous exercise is a major contributing factor to the obesity epidemic but a Canadian research team has discovered a new twist in the exercise/obesity issue.  They say exercising the intellect works up an appetite, with the need to replenish the brain’s supply of fuel as a possible reason for the hunger that follows intellectual involvement.

Dr. Angelo Tremblay, of the Universite Laval, Quebec City, and his colleagues enlisted 14 students to do three tasks during which blood samples would be collected.  The research team also documented the amount of food spontaneously eaten by each study participant after completion of each of the  three 45-minute tasks.

Previous research identified the number of calories burned during a 45-minute, sitting, rest period, one of the three tasks under study.  The same research showed that reading a text and summarizing it, the second task, burned only three calories more than are burned during sitting rest.  The third task, completing computerized tests of attention, memory, and vigilance, also burned just three calories more than the rest while sitting.

In spite of the low caloric expenditure involved with reading and the computerized tests, the number of calories consumed afterward varied dramatically.  When presented with a buffet of food after each task, students ate 203 calories more (23.6%) than they did after just resting.  After the computerized tests, caloric consumption jumped to 253 more calories, or 29.4% more than after resting.

The students’ blood samples, taken before, during, and after each task, revealed fluctuations of glucose and insulin levels that grew along with the intensity of the mental challenge.  The research team suggests the fluctuating levels of glucose and insulin may be a response to the stress caused by the intellectual work-outs but it may also be the brain’s way of replenishing the glucose lost to the intellectual work.  Glucose is the only source of fuel used by the brain and increased appetite may be the brain’s way of restoring its glucose supply to optimum capacity.

As a growing number of people take on sedentary jobs that require more intellectual than physical work, the research suggests this type of work may need to be examined as a contributing factor to the obesity epidemic.  Full details of the study are available in the current issue of Psychosomatic Medicine.