Regular readers will recall a recent post asking whether the reason that some people lose weight with exercise is that it helps them reduce their caloric intake (e.g. by improving mood, reducing stress, improving self-esteem, promoting sleep, etc.).
I also noted that, if this was indeed the reason behind any ‘exercise-related’ weight loss, then it probably does not matter how many calories were actually burnt as long as the amount of exercise was enough to positively influence ingestive behaviour.
A recent article, published by Jean-Philippe Chaput (Ottawa) and colleagues in the American Journal of Clinical Nutrition, now suggests that the notion that sedentariness and playing video games contributes to obesity because of reduced caloric expenditure is also flawed – the real reason some kids (and adults) gain weight playing video games is more likely due to increased caloric intake.
In their study, the researchers used a randomized crossover design to examine the effect of playing a video game for an hour (vs. just sitting around) in 22 healthy, normal-weight, male adolescents, on spontaneous food intake, energy expenditure, stress markers, appetite sensations, and profiles of appetite-related hormones.
Markers of mental stress including heart rate, systolic and diastolic blood pressures, sympathetic tone, and mental workload were significantly higher during the video game play condition than during the resting condition and energy expenditure was also modestly higher during the video game.
More importantly, however, spontaneous caloric intake after the video game exceeded that measured after rest resulting in a daily energy surplus of 163 kcal compared to resting for an hour.
The increase in food intake associated with video game play was observed without increased sensations of hunger and was not compensated for during the rest of the day.
Thus, this study strongly suggests that the reason kids (and adults?) may gain weight when playing video games is not because they are not burning calories but because they are eating more.
Although this study looked at videogames, it may be fair to assume that any form of inactivity that increases mental stress (work, play, or watching a hockey game) can translate into increased caloric intake.
This makes a lot of sense as in the vast majority of cases, weight gain has more to do with excessive caloric intake than with reduced caloric expenditure (although there are certainly important exceptions to this rule).
Based on this and previous studies, I believe it is fair to conclude that neither weight gain with increased screen time nor weight loss with exercise has anything to do with the burning of calories. Both effects are far more likely to affect weight because of their impact on caloric intake.
This is probably why reducing screen time and increasing physical activity should be part of dietary counseling for weight management.
Chaput JP, Visby T, Nyby S, Klingenberg L, Gregersen NT, Tremblay A, Astrup A, & Sjödin A (2011). Video game playing increases food intake in adolescents: a randomized crossover study. The American journal of clinical nutrition PMID: 21490141
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