While eating chocolate is associated with an instant reduction of emotional tension and tiredness, it causes an increase in both of these things in the long term.
Researchers are increasingly looking to the contribution that snacking behaviors and factors that interrupt self-regulation might make to rising obesity levels.
Previous studies have found that, on average, 97% of women and 68% of men experience food cravings, and that specific situations - such as being stressed or feeling down - tend to drive the cravings for sugary snacks that are high in calories.
Also, studies have found that while eating these foods is associated with an instant reduction of emotional tension and tiredness, the effects are purely short term, with both tension and tiredness increasing in the long term.
Some studies have found that exercise can reduce the cravings for snacking and for chocolate in particular. Because exercise can make people feel more active and positive, researchers have wondered if this is the mechanism that lowers the urge to consume stimulants to regulate mood.
The researchers behind the new study, from the University of Innsbruck in Austria, wanted to investigate whether replacing sedentary behavior with a 15-minute bout of physical activity is an effective aid for breaking the habitual consumption of snack food.
For the study - the results of which are published in the journal PLOS ONE - the team recruited 47 overweight people with a mean age of 28 who reported eating chocolate or other high-calorie sugary snacks on a daily basis. The participants were asked not to eat these foods for 3 days before they were randomized into one of two groups.
Researchers induced stress in the subjects before offering them candy
Half of the participants had a brisk walk on a treadmill while the other half were simply required to sit quietly for the same period. This was followed by 5 minutes of sitting quietly for both groups, and then all participants took a test that is known to elicit high levels of stress - the Stroop test.
In the Stroop test, the names of various colors are presented in a different color (the word "blue," for example, might be colored red), and the participants are asked to distinguish between the color of the lettering and the written name of the color.
The next challenge may have been even harder. Participants were offered a selection of sugary snacks and asked to unwrap one snack of their choice and handle it for about 30 seconds. While doing so, the researchers measured the participants' heart rate and blood pressure to gauge their level of craving and "emotional arousal."
The authors found that the Stroop test did induce stress among the participants and that this stress increased candy cravings in turn. However, participants who had been part of the treadmill group reported decreased cravings compared with the sedentary group.
Similarly, the participants who exercised demonstrated lower levels of cravings while handling the sugary snacks, whereas the participants who did not use the treadmill showed elevated pulse rates and reported stronger cravings while handling the snacks.
"Short bouts of physical activity may reduce the craving for sugary snacks in overweight people," the authors conclude. "When snacking has become habitual and poorly regulated by overweight people, the promotion of short bouts of physical activity could be valuable for reducing the urge to consume at times when the person may be particularly vulnerable, such as during stress and when snack foods are available."