watching tv and metabolic rate

TV Viewing & Resting Energy Expenditure

It is intuitive to assume that children burn fewer calories while watching TV than if they were involved in more physically active pursuits.   But is it possible to burn fewer calories than a coach potato?  Research suggests that TV viewing can cause just that.

In a study performed at Memphis State University, researchers examined just what happens to a child’s metabolic rate once they start watching TV.  Using an instrument like the KORR ReeVue, Resting Energy Expenditure or Resting Metabolic Rate (RMR) was measured while each child simply lay in bed, then compared to a measurement taken while laying in bed watching TV.  The result was that RMR actually dropped significantly while watching TV, by a mean of 211 calories!

The subjects included both obese and normal weight children, ages 8 to 12.  Half were assigned to view television followed by the no-television condition, while the other half reversed that order.  All arrived fasting and each received 3 RMR tests: one as a baseline, then two under test conditions.

What conclusions were drawn?  Primarily, that children who watch an excessive amount of television are more at risk for becoming obese because their resting energy expenditures are lower than if they were doing nothing at all.  To further complicate matters, obese children have been shown to watch more television per day than normal-weight children, causing them to have lower metabolic rates over time.  Additionally, studies indicate that the amount of time spent watching television at ages 6 to 11 years is a significant predictor of those who will become obese at ages 12- 17 years.

This is important for each of us to consider, whether evaluating the lifestyle patterns of a pediatric patient or when turning on the TV for our own children.   Even if obesity is not a current concern and 211 calories per day may seem inconsequential, it does add up.  22 pounds in a year, to be precise.  And that doesn’t even take into account the commercial driven junk food consumption that inevitably accompanies TV time.    Clearly, it’s time to turn off the tube.

Source: Pediatrics. 1993 Feb;91(2):281-6.  Klesges RC, et al.  Effects of television on metabolic rate: potential implications for childhood obesity.

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