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A study published in the May 2011 edition of the American Journal of Clinical Nutrition reports that teenaged boys eat more after they play video games and less when they relax.

Stimulation Packs on Pounds, Relaxation Curbs Overeating

Dr. Jean-Philippe Chacut, lead researcher for this clinical trial which was conducted at the Children's Hospital of Eastern Ontario Clinical Research Institute in Ottawa, explains that there is something about video gaming that changes eating habits in teens. This study conducted by Dr. Chacut and colleagues fits into a much larger body of evidence that supports the idea that almost any kind of intellectual activity, whether work or play, stimulates appetite.

For this clinical trial, the Canadian scientists recruited 22 healthy, normal-weight teenaged boys aged 16 and 17. In one branch of the trial, the scientists had the boys play a video game and then eat as much food as they wanted for lunch. In the other branch of the trial, the scientists had the boys rest in an upright, seated position for an hour and also take lunch, again allowing them to eat as much as they wanted from the same menu of food choices.

The findings of the study were counterintuitive. Engaging in no purposeful activity at all resulted in smaller appetites. Engaging in an intellectually challenging fun activity, not requiring expenditure of physical effort, resulted in measurably larger appetites. The teenagers in the study ate significantly more food when they played video games before lunch than when they spent the hour relaxing, even though playing video games does not require very many calories.

Playing a video game increased heart rate and blood pressure. It increased brain activity. The increased metabolic activity required to play the game, however, only required about 20 calories more energy than sitting and relaxing. The effects of playing the video game on appetite, however, stimulated far more than 20 calories of additional eating.

When the boys played video games before lunch, they ate, on average, 163 calories more than when they just lounged around waiting to be fed. These additional calories were not offset by additional activity later in the day. Nor were they offset by additional activity later in the day. The additional calories eaten after video gaming were presumably stored away as fat.

Exactly why playing a video game should increase appetite remains a mystery to the scientists. The research team did not find that playing video games increased the sensation of hunger. They did not find changes in insulin levels, blood sugar levels, stress hormone levels, or concentrations of the hunger hormone ghrelin.

Just 163 additional calories a day, however, translates into more than an additional pound of fat each and every month. Could video games be the cause of the epidemic of obesity in children and teens? Not as a sole factor, Dr. Chaput says. The Canadian research team recommends that in general teens limit their time in front of TV screens and that parents should set a good example by going outside and exercising with their kids, making calorie-burning a parentally approved activity.

While this study is the first to look at the effects of video gaming on appetite, there is considerable  additional evidence that the appetite-inducing effects of mental activity are not limited to video games. Almost any intellectual activity can stimulate appetite without stimulating additional burning of calories.

"Brain Work" Also Increases Appetite

Another study conducted by Dr. Chaput while he was with the Department of Social and Preventive Medicine at the University of Laval in Quebec found that doing intellectual work likewise increases appetite. For this study, Dr. Chaput and a colleague recruited healthy female college students, average age 24, for a test of appetite after performing intellectual work.

In one arm of this study, the female volunteers were assigned an article to read and told to write a 350-word summary on a computer. They were then treated to an all-you-can-eat lunch buffet. For the other arm of the study, the female volunteers were just treated to an all-you-can-eat lunch table.

Dr. Chaput's team previously had given the volunteers psychological tests to measure anxiety levels and possible eating disorders. They also took readings of pulse rate and blood pressure, and noted whether the participant was underweight, normal weight, or overweight. (None of the participants in the study was obese.)

The findings of this study?

  • Intellectual activity similar to writing a class paper stimulated the appetite even more than video gaming. While the teenaged boys who played video games ate an average of 163 calories more at their buffet meal, the young women who wrote article summaries ate an average of 250 calories more.
  • Intellectual activity does not stimulate cravings for any particular kind of food, just for more food in general. Neither study's participants had any preference for carbohydrate foods, protein foods, or fatty foods—just more food.
  • Intellectual activity did not make either group feel hungrier. They just ate more, without wanting to eat less the rest of the day.
The teenaged boys playing video games ate enough additional food to gain about 1.3 pounds (600 grams) a month. The college women writing article summaries at enough additional food to gain about 2.2 pounds (a kilo) every month. It would almost seem that the explanation for the obesity epidemic is "anything done in front of a TV or computer screen."

There is one other factor at work in the weight gain effects of additional eating after intellectual activity, whether it is for work or for play. Scientists have known for a long time that irregular eating habits result in inefficient energy storage, inefficiency being a good thing if you want to avoid weight gain. An occasional additional 150 to 250 calories will tend to be burned off rather than stored. But if the body gets those additional 150 to 250 calories each and every day, it will tend to burn them off rather than storing them.

Brain work packs on the pounds. Regular brain work packs on even more pounds. It helps to be aware of increased appetite so one can intentionally eat less, and it also helps to vary the schedule as much as possible so the body does not get in the "habit" of putting on pounds.
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  • Chaput JP, Tremblay A. Acute effects of knowledge-based work on feeding behavior and energy intake. Physiol Behav. 2007 Jan 30, 90(1):66-72. Epub 2006 Oct 3.
  • Chaput JP, Visby T, Nyby S, Klingenberg L, Gregersen NT, Tremblay A, Astrup A, Sjödin A. Video game playing increases food intake in adolescents: a randomized crossover study. Am J Clin Nutr. 2011 Apr 13. [Epub ahead of print]
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