If you’ve had a hard day at the office, new US research suggests that exercise after completing your day’s work could actually help to curb rather than increase your appetite. Previous research has shown that completing everyday mentally demanding tasks can affect how much energy the brain needs, and therefore increases food intake.
However the new study, which set out to investigate if the glucose and lactate produced through exercise could meet these energy needs instead of food consumption, found that those who took part in physical activity after completing a mental task actually ate fewer calories than those who completed the task but didn’t exercise.
In the study a team of researchers from the University of Alabama at Birmingham divided 38 undergraduate students into two groups and asked all participants to complete a graduate-level entrance exam. After the exam, one group was given 15 minutes to rest while the other was asked to complete 15 minutes of high-intensity interval training on a treadmill. After their 15 minutes of either rest or exercise, both groups were offered an all-you-can-eat lunch of pizza.
So that the results could be compared to a control, the week previously participants had also been asked to spend 35 minutes relaxing only, with no mental task or exercise before eating. The results showed that those in the “rest” group ate an average of 100 calories more than when they had relaxed the week previously, providing further evidence to suggest that the brain does indeed use more energy, leading to increased levels of hunger.
The participants who were in the “exercise” group ate 25 fewer calories less than when they simply relaxed before eating. The researchers noted that a possible explanation for the results is that although blood glucose levels remained stable in those who had taken part in exercise instead of rest, there was a significant increase in lactate levels which may have helped meet the brain’s energy needs.
However the team indicated that further research in the area is needed to better understand the effect of glucose, lactate and exercise on energy demands and calorie intake after mental work. The findings can be found published online in the journal Medicine & Science in Sports & Exercise.