ILLNESSOPEDIA

'Children can outgrow obesity' - Exclusive interview

Researchers have developed a model revealing how excessive calorie intake can affect the weight of children and adolescents, suggesting that children can grow out of obesity, according to a study published in The Lancet Diabetes and Endocrinology.

Researchers from the National Institute of Diabetes and Digestive and Kidney Diseases, as well as the National Institutes of Health in Bethesda, say the model could lead to the development of new weight-loss programs for obese and overweight children.

Exclusive interview

Dr. Kevin Hall - lead study author and senior investigator at the laboratory of biological modeling at the National Institute of Diabetes and Digestive and Kidney Diseases - took part in an exclusive interview with blog.

Why did you develop this model?

"We wanted to better understand how growth in childhood and adolescence affects metabolism and body fat over time and how childhood obesity develops on this background of healthy weight gain during growth.

"We previously built a model of adult metabolism that quantified how changes in diet and physical activity lead to changes in bodyweight and body fat. We found that the adult model was much more accurate than previous calculations of weight changed based on the so-called '3,500 calorie per pound' rule."

"In this new study on childhood growth and weight gain, we also found that previous calculations were very inaccurate and that there are substantial differences between children and adults when it comes to quantifying the excess calories needed to become obese."

How does the model work and why is it deemed so accurate?

"The model is based on the principle of energy balance, where bodyweight and body fat changes are accounted for by imbalances in the number of calories eaten in the daily diet and the calories used to maintain life through metabolism and perform physical work.

"The model of metabolism was adapted from our previously published adult model, but now accounts for sex specific growth. We tested the model by comparing its predictions to the results from clinical studies in healthy weight and obese children that were not used to build the model."

"The fact that the model predictions agreed with the clinical data gives us confidence that the model is accurate."

What makes this research stand out from previous findings?

"Most previous estimates of how many calories are required to generate childhood obesity did not account for healthy growth or the increase of metabolism that occurs with weight gain.

"The result was that previous findings suggested that a very small increase in calorie intake was responsible for the observed excess weight.

"Our more comprehensive model suggests that children require many more excess calories to accumulate excess weight and that this amount is even greater than in adults."

"This research now allows for accurate predictions about the caloric balance responsible for childhood overweight and obesity as well as providing quantitative benchmarks about the changes required to halt obesity at the population level as well as treat obesity in the clinic."

Original news article continued:

According to the Centers for Disease Control and Prevention (CDC), childhood obesity has more than doubled in the past 30 years. Statistics in 2010 showed that more than a third of children and adolescents were overweight or obese.

The study authors describe this model as a "mathematical representation" of the energy balance principle, wherein changes in bodyweight are calculated to analyze the relationship between the calories consumed in food and the energy used up by the body in order to carry out physical work.

The model analyzes how children's metabolism, growth and energy expenditure can change as they gain weight.

First model to distinguish abnormal from normal weight gain

The researchers say this model is the first to differentiate between the healthy weight gain that is normal in childhood and the excessive weight gain that results in obesity.

They add that it provides an accurate representation of how a child's energy balance can affect their weight gain.

The model was tested against data from previous studies that assessed the effects of a variety of weight loss interventions in overweight and obese treatments. This model was the most accurate tool in predicting the effect of calorie intake on weight loss in children, the researchers say.

Results predicted increases in energy intake between the ages of 5 and 18 of around 1,200 kcal a day in boys and 900 kcal a day in girls.

Children could 'outgrow' obesity

The model shows how some children could "outgrow" obesity during growth spurts, without changing their bodyweight, the study authors say.

For example, boys who are obese but maintain the same bodyweight during their growth spurts - which are more prominent between the ages of 11 and 16 - are likely to "normalize" their body fat as they grow taller and add lean tissue mass.

The researchers say, however, that this is less likely in girls as they tend to lose less body fat compared with boys, who tend to grow taller.

Potential for better weight loss interventions

The study authors say that this model could lead to a greater understanding within clinicians and policy makers of how weight loss treatments, such as exercise programs and calorie-controlled diets, can be used to determine the best and most effective way of addressing childhood obesity.

Dr. Kevin Hall, lead study author, says: "One of the most disconcerting aspects of the global obesity epidemic is the high prevalence of childhood obesity, which carries both health and economic consequences." He adds:

"The model we have developed is a substantial step forward in fighting this rising tide of childhood obesity. It allows us to accurately predict how a child's energy intake affects his or her likelihood of becoming overweight or obese."

However, the researchers say that this model may not be accurate in predicting the risk of obesity in all children.

"Though the model doesn't apply perfectly to all children - for instance, those who start adolescence late, or who undergo particularly rapid weight gain - it provides an accurate representation of the average effect of reducing or increasing calorie intake on the weight of children," says Dr. Kevin Hall, adding:

"Our future research will adapt the model to individual children as well as study the effects of increasing physical activity along with diet changes."

Families 'should be educated' on children's diets

Professor Claudio Maffeis of the department of life and reproduction sciences at the University of Verona, Italy, makes a comment in a follow-up to the study, stressing the "importance" of this research and saying it needs to be backed up by increasing parental knowledge.

He says: "To translate into practice these desired changes in energy balance, it will be necessary to increase families' knowledge and awareness of energy content and composition of children's diets by designing effective and sustainable educational programs about nutrition."