Time spent watching television

Time spent watching television

 

Most of the studies focusing on this subject have been
conducted in the USA on a national level and have shown a
correlation between the time spent watching television and
the nutritional status of the subjects involved.3–5
Over the years, many researchers have demonstrated a
positive correlation between time spent watching television
and being overweight or obese on populations of different
age. Most of these studies are cross-sectional,4,5 and therefore
the relationship between television watching (cause) and
obesity (effect) can only be suspected, and not asserted, as
the cause–effect relationship could be reversed: obese
subjects watch television for a longer time.
However, in a study conducted by Gortmaker et al,4 the
odd risk of being overweight was 4.6 times greater for
subjects who used to watch television for more than 5 h per
day as compared with those watching for 0–1 h. In addition,
Dietz and Gortmaker3 found a statistically significant
association between the number of hours spent in front of
television during childhood, at 6–11 y of age, and obesity 6 y
later.
The most ‘long-lived’ of the longitudinal studies on this
topic focused on an observation of children from preschool
age through early adolescence and demonstrated that
television watching is an independent predictive factor of
an increased BMI,13 while a study limited to girls, conducted
in North California for 2 y, failed to show any relationship
between the time spent watching TV and the development of
obesity.6 These different results could be ascribed not only to
the different age classes of the subjects under study, but also,
and perhaps most importantly, to the different lengths of the
periods of observation, which was much longer in the
Framingham Study. The effects of television watching on the
development of obesity could be visible only after a long
period of time (a period of more than 2 y) and could remain
undetected after a few months or even years of observation.
An additional proof of the impact of the amount of time
spent watching television on the development of obesity can
be derived from some trials in which the reduction of the
time spent watching television, as the only intervention
tool, has caused a reduction of body weight of the studied

subjects.6,14

Secondly, comparing the data published by Dietz
and Gortmaker in 1985 in NHES 1963–1970,3 and those
published by Crespo et al5 in NAHNES 1988–1994 in 2001,
the rate of children watching television for more than 4 h
per day seems to have increased at the same pace as the
rate of overweight and obesity in children. On the other
hand, some children start their experience with television
even at the age of 1 y; hence, one can readily understand
how slowly and, at the same time, strongly the relationship
between the time spent watching television and childhood
obesity develops.15 Finally, it has been demonstrated that
heavy-viewer children are from families where parents also
spend a lot of their time in front of television.16 On the basis
of these studies, the first recommendation about television
intended as tool to prevent obesity would be to reduce the
time spent watching television by children and also by their

families.

 [Source: International Journal of Obesity]