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Tubby from the
Telly?
The Link Between Television and Overweight
In identifying the factors most
closely linked to overweight, the American Institute for Cancer
Research (AICR) 2007 report on diet, physical activity and cancer
prevention advises the public to be physically active. The report
also specifically recommends limiting sedentary habits such as
watching television. Now, more recent studies add to emerging
evidence that TV’s impact on weight may be substantial.
A negative impact from television
time is seen in children as young as 2 to 5 years old. In a large
national survey, higher weight was 34 percent more common among
those children who watched more than two hours of television
daily. In adolescence, the association remains strong for girls,
while the link between TV and overweight becomes less consistent
for adolescent boys. |
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By adulthood, the link is again
consistent for both genders. In a study of 26 to 36-year-olds,
those watching more than three hours of TV daily were more likely
to have excess waist fat than those watching an hour or less.
Elsewhere, middle-aged adults who watched more than four hours
of TV daily showed waists averaging over an inch larger than
those watching less than two hours daily; their percent body
fat and body mass index were also higher.
It’s easy to assume that
the television-overweight link occurs when TV replaces physical
activity. For many people, this does hold true. But even when
TV doesn’t displace physical activity, research shows that
we move around less and burn fewer calories when watching TV
than when participating in other sedentary activities like playing
board games, writing, reading or sewing.
Indeed, studies repeatedly find
that the amount of time people are physically active and the
amount of time they spend watching TV affect body weight independently
of each other. In one study of Australian adults, spending a
lot of time in sedentary behaviors increased the odds of being
overweight or obese by more than 50 percent, even among participants
who got the recommended amounts of physical activity. Lots of
sedentary time and too little time being physically active more
than doubled the odds.
Television also seems to impact
weight by affecting our eating habits. Dinner in front of the
TV is less likely to include vegetables and fruits according
to some studies. In a study of four- to seven-year-olds, when
television and computer time was cut in half, calorie consumption
decreased significantly. Among Canadian college students, not
only was greater TV viewing linked with more frequent snacking
while watching TV, it was also associated with greater consumption
of high-calorie snacks compared to students with little TV time.
These students also displayed increased advertising awareness,
which was the strongest tie to greater consumption of those high-calorie
snacks.
Even commercial-free TV is likely
to increase calorie consumption, according to experts. When we
eat while we are distracted by other activities, we are more
likely to continue eating without noticing subtle body signals
that we are no longer hungry. |
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