Preventing Childhood Obesity - Evidence Policy and Practice.pdf

Obesity prevention in secondary schools
Snacks now account for a substantially larger percentage
of total daily energy and macronutrient intake
than they did in the late 1970s. 3
Physical activity in adolescents is on the decrease
and low levels of activity seem to persist into adulthood.
Not only does lack of physical activity increase
a young person ’ s risk for overweight and obesity but
may contribute to cardiovascular disease, cancer and
osteoporosis in later life. The increasing lifestyle of
sedentary behaviors means the development and evaluation
of physical activity interventions is, therefore,
a priority for the promotion of adolescent health.
Sedentary behavior in adolescence is often mentioned
as risk factor in obesity development and may
have a link to its increasing prevalence and severity.
The increase in playing digital games, using computers
and especially watching television, have been associated
with obesity. The link between obesity and
television viewing has suggested that there is a delayed
effect of TV viewing on body fatness. 4 This suggestion
resulted from longitudinal studies, specifically focusing
on girls who exceeded two hours of television
viewing per day. 4 During adolescence, boys generally
tend to spend more time playing videogames than
watching television. Videogames contribute more to
energy expenditure than watching television. 5 This
increase in energy is very minimal and does not
diminish the risk of overweight and obesity. Computer
use is also a major contributor to increasing sedentary
behavior but at this stage there is no evidence to
suggest a link with overweight and obesity in adolescence.
There is a real lack of research in this area. 4
Overall, with screens increasingly taking up adolescents
’ leisure time it is still unclear from the research
whether or not sedentary behavior replaces physical
activity 4 and what the impacts are on obesity development.
There is sufficient evidence to recommend that
adolescents have limits placed on their time spent
watching television, that video game playing should
be carefully monitored, and ensure that time spent on
computers does not reduce physical activity levels. 4
A diverse variety of settings have an impact on children
’ s and adolescents ’ behavior. Many environments
and numerous stakeholders, including parents, teachers,
peers and many more, can or should be involved
to stimulate activity and/or improve dietary patterns.
The counteracting factors are difficult for all of those
involved in the prevention of overweight and obesity
in adolescents. Children and adolescents are of particular
focus for obesity prevention because overweight
adolescents are at elevated risk for obesity in
adulthood. 5 The evidence suggests there is a role to
play from many different parties including: schools,
family, individual and policy. 6 From the evidence, it
is difficult to conclude what are the best strategies
to reduce overweight and obesity in adolescents.
However, it is possible to suggest from those studies
that have effective outcomes which strategies might
have the most success in reducing overweight and
obesity. The way that information and interventions
are delivered will vary and also counter cultural
barriers.
There are also potential differences from effects
such as gender, age and ethnicity (e.g., Doak et al) 7
and the effect of gender has been suggested to be
linked to physical activity focus. 8 The evidence is
unclear with regard to age and ethnicity as the studies
that focus on these determinants are few and often
low on quality. 7 Further studies are required to cross -
compare ethnicity groups and stratify age groups
in order to make any conclusions. This chapter
provides an overview of what the key learnings are
for beginning the process of reducing obesity in
adolescents.
School, f amily and
c ommunity a pproaches
As discussed in Chapter 10 (Obesity prevention in
primary school settings: evidence from intervention
studies) the associated determinants that influence
overweight and obesity are complex and vary across
communities and cultures. The link between community
and the individual is in itself an important
part of obesity prevention. Communities will often
have to lead and may even implement government
initiatives — therefore, it is important for teachers,
schools, parents, families and adolescents to be provided
with the knowledge and skills that may assist in
the prevention of overweight and obesity (e.g., Sluijs
et al). 9 When identifying potential strategies for what
may work at community, school or home levels, it is
important to remember that strategies which may be
more effective are those which build on ideas for
appropriate interventions derived from children ’ s
views and experiences. 10 The building of knowledge
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