Preventing Childhood Obesity - Evidence Policy and Practice.pdf

Chapter 29
length gain observed in apparently “ healthy ” children.
This has led in practice to support the notion that
“ bigger is better ” . This is a reasonable approach if the
objective is to enhance survival in infancy and early
childhood in areas where malnutrition and infection
in synergy claim the lives of infants and young children.
However, it is certainly not the case in countries
where deaths of young children are rare and the
concern has shifted to the prevention of obesity and
related burden of chronic disease. 1 Moreover, there is
also mounting evidence that exposure to undernutrition
during early life (i.e. in utero and the first two
years of life) may have long - term consequences for
adult body composition and health if there is a mismatch
between early nutritional deprivation and later
nutritional conditions that may support rapid weight
gain in childhood. 2 – 4 Thus, the definition of “normal ”
growth is of paramount importance to secure normal
health and nutrition of both individuals and populations
in developed and developing countries.
Growth r eferences and s tandards to
d efine g rowth in e arly c hildhood
The reference/standards used to assess growth are fundamental
for both clinical practice and to establish
public health recommendations. Normative gender
and age specific data of weight, height, weight/height,
and BMI have been used as indicators of nutritional
adequacy in infancy, childhood and adolescence.
Most of the available growth charts are based on the
observed growth for a normal reference population
rather than recommended growth based on health
outcomes throughout the life course. Until 2006, the
growth charts most commonly used were based on the
USA National Center for Health Statistics ( NCHS )
The NCHS growth reference, which originally served
as the basis for the WHO international growth standards
for infants aged 0 – 36 months, was derived from
children growing in an affluent rural society in the
town of Yellow Springs, Ohio. 2 However, these references
had major flaws because they were derived from
a non - representative sample of the population and the
infants included were predominantly formula fed and
received energy - dense complementary foods. Thus,
the NCHS distributions of normal weight - for - age and
weight - for - length are skewed towards higher values,
relative to those observed in predominantly breastfed
infants and this may have been a contributory factor
to the increase in childhood obesity, since normal -
sized children may have been considered underweight
and prescribed additional energy.
Aware of these limitations, in 2006 the WHO
launched the Multi - country (Brazil, Norway, India,
Ghana, USA and Oman) Growth Reference Standard
( MGRS ). The MGRS was developed based on the
growth of infants and children from diverse geographical
regions, whose mothers were non - smokers of
middle to high income so that environmental conditions
were not restrictive for growth, and care givers
followed the established WHO feeding recommendations
(i.e. infants were predominantly breastfed for
4 – 6 months and fed appropriate complementary
foods after weaning). 3 The new international growth
reference provides a scientifically reliable descriptor of
physiologic growth and a powerful tool for advocacy
in support of good health and nutrition. Most importantly,
this reference is based on the growth of the
breastfed infant as the normative standard.
Definitions of o verweight and
o besity in c hildren
In children, there is a lack of consistency in the use of
the terms “overweight ” and “obesity ” . All recommendations
take into account two levels of excess weight,
but use of different definitions and terminology may
lead to confusion in interpreting results and comparing
prevalence across populations. This is further
complicated by the lack of evidence on the most
appropriate anthropometric indices and cut - off points
that best predict long - term adverse health outcomes.
BMI has been used to define categories of excess
weight so that there is concordance with adult assessment,
although for children the definitions are age
and sex specific. The 2000 CDC growth charts provide
BMI - for - age curves for the US population over 2 years
of age 4 and define children with a BMI ≥ 95th percentile
as “ overweight ” and children with BMI between
the 85th and the 95th percentile as “ at risk of overweight
” . 5 The WHO growth standards for 0 –5-yearolds
in combination with the new WHO reference for
5 –18-year-olds provide an international reference
from birth to 18 years. 6 The terminology for body size
categories (thinness, normal weight, overweight,
obesity) using the WHO and International Obesity
Task Force charts ensures concordance between adults
and children because the childhood BMI curves were
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