Endocrine and single gene disorders causing obesity in childhood are rare, accounting
for 1–2% of obese children seen in a tertiary care setting. Nevertheless, an understanding
of these disorders is required to recognise rare but treatable causes of
childhood obesity. A thorough description of these conditions is beyond the scope of
this review and can be found elsewhere.
The majority of cases, however, arise from a simple interaction between host factors
that enhance susceptibility and environmental factors which increase food intake and
decrease energy expenditure. Factors causing the imbalance in energy intake and
energy expenditure are numerous, simply reflecting the components of the obesogenic
environment in which we live. Factors important in excessive energy intake include the
consumption of energy-dense foods, increased portion sizes, between-meal snacking
and regular intake of sugar-sweetened beverages and fruit juices. Decreased energy
expenditure is often due to the coupling of increased sedentary activities, such as TV and
computer games, alongside decreased physical activity. There are also very significant parental and socioeconomic [1, 17] contributions to obesity risk as demonstrated by
a recent study which showed that while 89% of parents of overweight 5- to 6-year-olds
were unaware that their child was overweight, 71% were not concerned, with less educated
parents being less likely to take action . Ethnicity also significantly impacts
upon obesity risk and the development of co-morbidities. For example, data from several
countries show that black children have a higher prevalence of obesity than white children while obese children from certain ethnic groups (e.g. South Asia) appear to
exhibit higher rates of complications like T2DM for a given level of obesity .
Addressing these complex demographic and lifestyle interactions remains central to the
development of effective prevention and treatment programs for childhood obesity.
