May 11, 2010 - Source:
Medscape Medical News
A study on caloric intake in a large,
nationwide population of children and adolescents has revealed the
surprising finding that those who are clinically overweight and obese
consume fewer calories than their healthy weight counterparts,
beginning at around 7 years of age.
The study, which was presented here at the Pediatric Academic
Societies (PAS) 2010 Annual Meeting, was undertaken to clarify the
inconsistencies in previous research on caloric intake and weight in
children. Researchers have assumed that variation in caloric intake at
different ages was the basis of the variation in weight, but this had
not been explored.
"Our study provides the surprising finding that older overweight
children report consuming fewer calories than their healthy weight
peers. The finding indicates that intervention strategies solely
targeting energy intake in older children may face difficulties,"
study presenter Asheley C. Skinner, PhD, assistant professor of
pediatrics, Department of General Pediatrics and Adolescent Medicine
at the University of North Carolina at Chapel Hill School of Medicine,
told Medscape Pediatrics.
Dietary reports of 12,316 children and adolescents from 1 to 17 years
of age that had been complied as part of the National Health and
Nutrition Examination Survey (NHANES) from 2001 to 2006 were examined.
The diet records were gathered using the Automated Multiple Pass
Method (AMPM), a validated system of self-reported recall of the foods
consumed in the previous 24 hours, and "the best available tool for
reporting on a population basis," according to Dr. Skinner.
For children 5 years of age and younger, data were supplied by the
parents. Both parents and child supplied information for the 6- to
11-year group, and those 12 to 17 years supplied their recollections.
The AMPM is structured to provide ample opportunity to include
initially overlooked daily diet information, Dr. Skinner pointed out.
"The subjective nature of self-reporting is always a limitation of
studies such as this. But, the validity of AMPM for such reporting
purposes has been documented. Furthermore, there were no significant
differences in caloric intake among children close to age cut-offs,
reducing the possibility of recall bias," Dr. Skinner explained.
Weight status (overweight/obese, healthy, and underweight) was based
on the weight-for-length percentile in those 2 years of age or
younger, and on a percentile of body mass index (BMI) for those 2 to
17 years of age. Overweight and obese children were above the 85th
percentile, healthy weight children were in the 5th to 85th
percentile, and underweight children were below the 5th percentile.
The interaction of weight and age with energy intake was
statistically analyzed, while controlling for sex, ethnicity, race,
Dr. Skinner reported that weight status and age were significantly related (P < .001). Being obese, overweight, or of healthy weight was less influential to daily caloric intake in adolescents.
Children younger than 2 years of age who were overweight/obese
consumed a daily average of 1594 kcal; those who were healthy weight
consumed 1389 kcal. But the pattern "had flipped" in 9 to 11 year
olds, with the daily caloric intake of overweight/obese children being
1988 kcal and that of healthy weight children being 2069 kcal.
The caloric intake curves crossed at around 7 years of age, Dr. Skinner told PAS meeting attendees.
The flipped trend for energy intake between overweight/obese and
healthy weight children and adolescents was the same for boys and
girls, with boys tending to consume more calories than girls.
The pattern continued into adolescence. Those 15 to 17 years of age
who were overweight/obese consumed 2271 kcal daily, whereas their
healthy weight counterparts consumed 2537 kcal.
Again, the pattern was similar for both sexes, including a higher energy intake for boys.
One explanation for the unexpected findings might be that physical
activity differences with age play a role. At earlier ages, becoming
overweight or obese could be spurred by increased caloric intake.
Decreased physical activity with age could maintain the excess weight
even with reduced energy intake, Dr. Skinner postulated.
Puberty-related physiological changes might also affect the consumption of foods.
"These are intriguing findings, but it is worth remembering that
there are studies that have demonstrated that those with a higher body
mass index are likely to underreport their caloric intake," Jason A.
Mendoza, MD, MPH, assistant professor of pediatrics at Baylor College
of Medicine in Houston, Texas, told Medscape Pediatrics.
It turns out, however, that other studies have found that the
recalled energy intake of overweight and obese individuals is fairly
accurate, Dr. Skinner said.
So far, the study findings have not been parsed out in more detail.
Planned analyses of the data will stratify the findings on the basis
of factors such as income, the Chapel Hill team reports.
The study was funded by grants from the
National Institute of Child Health and Development and the Building
Interdisciplinary Careers in Women's Health program. The authors have
disclosed no relevant financial relationships.
Pediatric Academic Societies (PAS) 2010 Annual Meeting: Poster session 2863.511. Presented May 4, 2010.
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