Preventing Childhood Obesity - Evidence Policy and Practice.pdf

Obesity in early childhood and working in pre-school settings
anchored at age 18 years to the agreed adult cut - off
points (18.5, 25, 30 kg/m 2 for thinness, overweight and
obesity respectively). 7,8
Developmental o rigins of o besity
The relationship between low birth weight and the
later occurrence of obesity and central obesity has
been documented in a number of epidemiological
studies conducted mostly in industrialized countries,
9,10 and in follow - up studies of historic cohorts
from transitional countries. 11 In most developing
regions low birth weight, and underweight and stunting
in young children, coexists with overweight and
obesity in older children, adolescents and the adult
population; 12 thus, it is likely that the effect of low
birth weight in these countries will be higher than that
of developed countries. Analyses of the five existing
cohort studies from developing countries (India,
Guatemala, South Africa, Brazil and the Philippines)
have reported that in India, Guatemala and Brazil,
birth weight was positively associated with BMI at age
25 – 30, yet the associations were stronger for lean mass
than for fat mass. 11
Macrosomia or high birth weight (greater than
4,000 g) is also a potential problem with long - term
consequences. Excessive intrauterine growth in this
case is driven by elevated maternal glucose and insulin
levels due to gestational diabetes and/or maternal
overweight. 13 Several studies of macrosomic children
have shown that high birth weight is a risk factor for
14 – 17
later development of obesity and diabetes.
The importance of the existence and timing of a
period of rapid childhood growth in potentiating the
relationship between fetal undernutrition and later
obesity is a matter of current debate, 18,19 partly because
of the rapid changes in the environment associated
with progressive increase in the prevalence of obesity.
Older cohorts have subtle changes. The systematic
review by Monteiro and Victora 20 identified 16 studies
that presented data on the role of rapid childhood
growth as a possible determinant of obesity in adulthood,
13 of which reported significant associations,
although they also noted the significant lack of standardization
between studies making interpretation
difficult. The degree to which rapid infant growth represents
a risk may depend on whether it occurs in the
context of recovery from fetal growth restriction and
results in normalization of body weight and length, or
whether excess growth is predominantly ponderal
with constrained linear gain, thus leading to excess
weight for length. 11,21
The effect of rapid weight gain in early life may also
depend on prenatal and postnatal characteristics such
as exposure to tobacco in utero , maternal overweight
or obesity, the type of early feeding, or the amount of
fat in the diet. 22,23 Overall, the effect of rapid infant
weight gain on later development of overweight seems
to be relevant. In relatively contemporary cohorts of
children from USA it has been reported that the population
risk for overweight at 4 or 7 years attributable
to infant weight gain (0 to 4 – 6 months) in the highest
quintile is around 20%. 24,25 Another study in a non -
contemporary cohort of African-Americans reported
that almost 30% of the risk of overweight at 20 years
was due to a rapid weight gain (over one standard
deviation above the mean value) from 0 to 4 months
of age. 26 Given the actual increase in obesity among
children and adults, is likely that the attributable risk
might even be higher.
The age at adiposity rebound (age at which the BMI
increases after its nadir in early childhood) is another
period in which childhood growth seems to be critical
for later obesity. 27 On average, this normally happens
between the ages of 5 and 7 but it has been shown that
an earlier adiposity rebound is associated with
increased fatness later in life. 28 For example, one study
reported that adults who had their adiposity rebound
by 4.8 years had a 6 times higher risk of having a
BMI > 27 kg/m 2 than adults who had their adiposity
rebound after 6.2 years. 29 There remains some uncertainty,
however, over whether the apparent negative
effect of an early adiposity rebound is independent of
early life BMI or BMI percentile crossing. 30,31
Energy i ntakes and f eeding
p atterns in y oung c hildren
Recommended e nergy i ntakes
Energy recommendations for infants and children
published by FAO/WHO/UNU in 2004 are based on
actual measurements and estimates of total daily
energy expenditure, either by the doubly labeled water
method or estimates based on heart rate monitoring
during active periods coupled to individual calibrations
of oxygen consumption 32 The energy needs for
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