New Model Addresses Childhood Obesity

According to results of a new study, mathematical modeling may help healthcare providers and health policy makers develop real world interventions for children who are obese or overweight.

The study describes a unique model developed by Dr. Kevin Hall of NIH, and colleagues which demonstrates how excessive caloric intake impacts the weight of children and adolescents. Data from this model may potentially lead to more targeted and novel weight loss solutions for overweight and obese children.

The research is published online in Lancet Diabetes and Endocrinology July 29.

This new model is the first to distinguish between the so-called “healthy weight gain” which is normal and expected during childhood, and excessive weight gain that leads to children becoming overweight and developing obesity.

Hall’s model is based on the “energy balance principle”, which states that weight fluctuations are the result of a difference between calories consumed and energy expended. It accounts for the metabolic changes which occur when body weight fluctuates and also differentiates between the energy needs of lean muscle mass and fat or adipose tissue. The model additionally accounts for sex-specific differences in growth rates and metabolism. To account for normal growth-related energy requirements between the ages of 5 and 18 years, Hall and colleagues assumed a gradual increase of about 1200 kcal/day for boys and 900 kcal/day for girls. When tested against actual population data, the authors determined that the model accurately reflected cross-sectional data from 292 healthy white children, as well as data from Hispanic and African American children.

Based on Hall’s model, the development of childhood obesity was simulated by slowly escalating caloric intake from age 5 years while keeping all other variables consistent with healthy growth. According to this model, obese boys consumed a mean of 750 kcal/day more than healthy-weight boys between 5 and 11 years of age. For obese girls, the mean daily caloric excess was 850 compared with their normal-weight peers. At the end of the time period, the mean daily caloric differences were 1100 for boys and 1300 for girls, compared with healthy-weight children.

Based on the current findings of this study, the authors believe that previous models have significantly underestimated the caloric intake of obese and overweight children. As an example, current models used by policy makers and health care providers predict that a 10 year old female who is 10 kg overweight, but who was at a “healthy weight” at age 5 has an excess caloric intake of about 40 kcal per day (caloric content of an apple). Meanwhile, the new model which is based on a better understanding of a child’s growth requirements, energy needs and expenditures, as a child gains weight, calculates that this overweight 10 year old girls is consuming 400 kcal more daily than a “healthy weight’ child her age. (the equivalence of a medium serving of French fries or a hamburger).

According to the new model, children may “outgrow their obesity” on a weight-maintenance regimen, with boys having an easier time than girls. In the authors’ simulation, by the age of 11 years, girls already had 9 kg more body fat than boys. At this level of additional fat, further weight loss would be necessary for normalization of body composition. In addition, it is important to time any weight loss program for the period of maximum growth (puberty), since weight-loss interventions begun at other times would be predicted to result in the loss of significantly less body fat.

Limitations of the study include failure to account for children whose weight gain followed a trajectory different than the steady increases assumed in this model, along with failure to estimate accurately for children whose growth rates as well as development are significantly outside the norm.

Intriguing from this new model is the concept that some children may be able to “outgrow” obesity during specific periods of rapid growth--particularly between the ages of 11-16--without actually losing weight. It turns out that obese boys who stay at the same weight during this time actually revert to normal levels of body fat as they grow in height while adding lean tissue mass. This effect, however, is not seen as clearly in girls because they lose comparatively less body fat than boys, who have a greater

potential for growth.

The reality, however, is that based on studies, food intake by obese children and adolescents is typically underreported to their parents. Most parents are minimally aware of their child’s actual portion size and amount of food intake. These inaccuracies contribute to the ongoing difficulties assessing their nutritional status and making plans to intervene.

According to Don Morris, Ph.D., Vice President of Scientific Products and Technology at Archimedes, a healthcare modeling an analytics company, the growing use and interest in mathematical models such as the one evaluating childhood obesity in Hall and colleagues, “is consistent with ongoing changes in the healthcare industry which will demand accountability for ongoing expenditures”. He adds, “prevention, detection, and early treatment will all be essential as part of any effort to attack public health problems such as childhood obesity.”

C. Andy Schuetz, Ph.D., Director of Population Products at Archimedes agrees, explaining that well designed models of diabetes, vascular disease and childhood obesity, can help clinicians and policy makers better evaluate the effects of specific diseases, in order to better develop “unique strategies for prevention, early detection and treatment of disease”.

The Value And Impact Of Mathematical Models In Disease Management

The use of mathematical models to simulate disease processes is an important step not only toward becoming more fiscally responsible, but also placing more attention toward early detection, treatment as well as disease prevention in our society.

In fact, previous research toward development of both diabetes and vascular disease models has resulted in tangible improvements in healthcare outcomes and health care savings, based on recent work by Schuetz and Morris of Archimedes. Their model is part of a recent study in 2010 which found that checking for diabetes earlier than the standard age 45 was able to reduce the incidence of microvascular complications and myocardial infarction as reflected in cost per quality-adjusted life-year (QALY).

Additional work recently published evaluating the effects of implementing standardized vascular checks on expected health outcomes, demonstrated that such health check strategies assessing diabetes, hypertension, smoking and lipid management over a 30 year period would likely improve health as well as cost-effectiveness outcomes in six European countries, including the UK, Germany, France, Denmark, Italy and Poland.

“This study marks an exciting step forward in Archimedes mission to improve the quality and efficiency of healthcare worldwide” said C. Andy Schuetz, Ph.D., Archimedes’ Director of Population Products, as well as the lead author for the study. With this work, we were able to provide a realistic model of European populations and their healthcare systems.”

More than 20 years ago, Archimedes began building a clinically relevant large scale model of populations based on human physiology, disease processes, along with interventions for health care systems. The core principle of its working technology is the Archimedes Model. At this time, the company’s validated model provides the backbone for its various solutions designed to help answer complex healthcare questions and to address the needs of both individuals and larger populations, such as those with diabetes and vascular disease. Archimedes continually validates the Model by comparing results of simulated trials to the results of cohort studies and multi-national clinical trials.

The Race To Address Childhood Obesity

Based on statistics indicating that over 30 percent of children in the US and England are overweight or obese, the new model may provide healthcare providers and policy makers with a better window to understand how weight loss approaches such as specific workout programs and calorie restricted diets can impact the epidemic of childhood obesity.

“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” says Dr. Kevin Hill, the lead author of the study.

He explains, “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.”

Hall ultimately believes that his research “can put some numbers” behind future interventions that are being developed for childhood obesity, especially “what targets or calories per day to reduce obesity would be successful”.

Hall explains that based on previous calculations, “it looked like a very modest effect would have been required to generate the obesity levels in children based on calories consumed per day”. Past calculations were likely underestimated and related to the small “energy imbalance gap”—that is, the small difference between calories children were consuming compared with energy being expended.

Hall’s research has expanded upon previous work by adding a “better accounting for the number of calories children are burning daily which are related to growth and development of excess bodyweight”.

He explains that “previous calculations had provided much smaller numbers required to generate the energy imbalance required to generate obesity and weight gain in children”.

“Just small changes at the policy level or even clinically,” Hall explains, may help to guide caloric intake in obese children to better manage the epidemic of obesity. Hall’s revised calculations (of additional calories) that lead to obesity are much greater than was previously thought.

Putting this into practice, he used his models to compare the caloric intake of children in the 1970’s prior to the obesity epidemic, to what children are eating today across the population, arriving at a figure that children today are consuming on average 200 calories more per day than children in the 1970s. He believes that the take home message is not actually to treat obese children today by reducing their intake by 200 calories per day, but rather to use this as information to guide or inform later generations as a comparison for weight gain across generations.

Morris agrees, and suggests that “compared to previous estimates, weight loss in children requires a larger caloric reduction along with more aggressive measures”. He concludes that a focus on caloric intake is essential in order to effectively make an impact on childhood obesity.

The explosion of electronic technology has further contributed to children engaging in less physical exercise. As a way to counter this trend, the use of mobile apps has been gaining popularity as a way to improve health. In a novel approach to this dilemma, Schuetz believes that “we can use the technologies that are causing the epidemic to fight the epidemic”.

According to both Morris and Scheutz, overall data obtained from a policy perspective from modeling can also provide individuals with greater information to make personal health choices as well. The brief pleasure of eating a highly caloric food compared with the need to burn excess calories to prevent weight gain and decrease intake is part of an ongoing educational process associated with such models.

The so-called “trajectory” of a child’s weight gain associated with poor eating habits and choices places them at a greater risk for onset of diabetes, and complications from diabetes, especially cardiovascular complications, according to Morris and Scheutz.

Hall, commenting on this concept of a “weight gain trajectory”, believes that some obese children may have the unique ability to actually “outgrow obesity”. This implies--without changing their weight-- essentially growing into their presently excess weight, which at a later age may be a “normal weight”. Simulations by Hall suggest this may be an effective intervention for children who are not excessively overweight at the outset of puberty, and for those who have not undergone puberty yet.

By harnessing this growth potential which is greater in boys than girls, a weight maintenance intervention described by Hall in the Lancet is shown to be more effective in boys than girls--even if both were instituted before puberty began.

According to Hall, girls, if not excessively overweight prior to onset of puberty, may also be able to “grow into obesity” by cutting calories and enrolling in weight maintenance programs. They will still have the ability to reduce fat mass and gain lean mass, but it will be more difficult if this is delayed until after puberty begins.

According to Hall’s models, while adults typically require high protein diets and resistance exercise training in order to decrease fat mass and gain lean muscle mass, “children can likely harness their innate growth potential [during puberty], producing gains in lean muscle mass while decreasing body fat, something which would be quite difficult to achieve in adults, and even more difficult to achieve after puberty”.

With the advent of apps and mobile technology for weight loss and management, whether individuals- including children- can assume ownership and become invested in weight loss has been debated. Hall explains that he has conducted previous studies utilizing mobile apps for adult weight loss tracking body weight, by calculating caloric intake linked to sequential body weight. He believes this mobile app technology could also have a role in children in the near future as part of future based models.

Focusing on portion size and frequency of food intake is important as part of an interventional program to fight childhood obesity. In general, parental awareness of most children’s portion sizes and overall amount of food intake is poorly understood. Going forward, it will be important to raise awareness and educate both parents and teachers about the importance of physical activity, targeted nutrition and portion sizes to help reduce childhood obesity.