Overweight and Obese Children Eat Less Than Their Healthy Weight Peers

Brian Hoyle

May 11, 2010

May 11, 2010 (Vancouver, British Columbia) — 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, and income.

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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