EDS: New study indicates putting overweight children on diets may slow or hamper their growth
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(STORRS, CT) When overweight adults seek to slim down, the prescription is pretty simple: decrease calories, or in more technical terms, create a "caloric deficit." This is often done with a diet, exercise, or both, and if the participants are successful, pounds are lost. So when faced with overweight children, parents, doctors, and others tend to recommend the same formula. Unfortunately, this may not be the best approach.
"Children are still growing," says Nancy Rodriguez. "Creating a caloric deficit can negatively affect the way children process protein, which in turn could slow or even compromise their growth."
This presents an interesting question: can overweight children lose weight without slowing their natural growth process? This question became the primary focus of a study that Rodriguez, an associate professor of nutritional science at the University of Connecticut, undertook in 1995. Underwritten by a grant from the American Heart Association, the study allowed Rodriguez and then-doctoral student Cara Ebbeling, to examine more closely how cutting calories and increasing activity would affect body composition and the use of protein in overweight children between the ages of 8 and 10 years. Their findings indicate that caution should exercised before putting a child on a diet.
"We found that diets should be combined with exercise, because dieting alone significantly slowed protein turnover, the way that protein is processed and used by the body," Rodriguez said. "If you slow this process down, then you may be hindering a child's growth." Protein turnover key to formula
Rodriguez and Ebbeling met in 1993 when Ebbeling she had just entered the doctoral program at UConn's department of nutritional sciences. Ebbeling, who is also an exercise physiologist, was very interested in focusing her doctoral studies on children. Up to that point, Rodriguez had focused much of her research on protein metabolism. Creating a study that looked at protein turnover, a basic reaction for growth, seemed like a natural collaboration between the two scientists.
The 12 week study Rodriguez and Ebbeling created was financed in part by a grant from the American Heart Association. The participants, overweight children 8 to 10 years old, qualified based on juvenile obesity standards and body fat percentages. Boys entering the study had to have a body fat of 25% or more; girls, 30% or higher. The selection process itself was an interesting experience.
"I had parents bringing me kids who were not fat at all. I mean not even close," Rodriguez said. "This was very disturbing but it's not uncommon. A lot of parents think that because their kids look a little chubby, they're overweight. We have to remember that these are kids. Their bodies are different from ours and in constant flux. But when you have a mother telling her daughter that she's fat, even though the girl is absolutely average by every test I could perform on her, then you're setting up the foundation for that kid to have an eating disorder. It's a recipe for disaster."
Ultimately, 25 qualified candidates were identified and enrolled in the study. The kids, 15 girls and 10 boys, represented a variety of ethnic groups.
The study's first two weeks served as a baseline control period. Participants were asked not to change their eating habits and activity (or lack of activity) rates. Food intake and activity were charted, as were baseline body composition measurements and protein turnover rates.
Rodriguez and Ebbling also met individually with the children to talk about eating habits and create a more balanced meal plan for each participant. This didn't mean starving or even skimping on meals. But the kids would have to deal with less of some foods -- often the fattier items -- and more of other foods such as fruits and vegetables. This is exactly the type of modification that sends many adults off their diets. How were the researchers going to be successful with often-finicky children? Rodriguez admits that it was a challenge, but substitutions and negotiation ultimately created success.
"Of course we had kids that hated vegetables, but we didn't encounter any that hated fruits andvegetables," Rodriguez said. "In their diets, fruit replaced vegetables. There were others who would only eat one kind of vegetable be it beans or corn or carrots. So we said to the parents, ëFine, carrots every night.' If the child likes them and eats them then it's better than a kid using cookies to supply those calories." And even though the study focused on protein, one of the participants was eating too much already and had to have his supply cut.
"This poor little boy actually cried because he just loved meat," Rodriguez said. "Beef, chicken, fish, all of it. But he ate too much of it at each meal."
Still, Rodriguez worked with the boy to not reduce his meat intake as drastically as first proposed.
"It took a little juggling, but we found a point that he could accept and that we were comfortable with calorically," she says. "I think this really helped because it showed him we were willing work with him."
After the two week baseline period, the participants switched to meal plans that reduced their intake by about 500 calories per day. In the final six weeks, a sub-sample of the children were asked to continue with the reduced calorie diets, but to also incorporate five days of walking per week into their activities. This created an added caloric deficit of between 100 and 300 calories per walk. Throughout the study, height, weight and body composition were charted and tests were performed to monitor protein turnover rates.
"Early-on, many of the kids were feeling better about themselves in general just for taking part in the study, even though their weight loss was not immediate or dramatic," Rodriguez said. "One eight year old boy after losing a single pound turned to the mirror and said, ëYep, I'm looking pretty good!'"
And yet, a few of the children began dropping out of the study after only a few weeks. Rodriguez quickly noticed a pattern among those who were leaving.
"The saddest part about this was that the vast majority of kids who dropped out were really trying to comply," she said. "But they were getting no support at home."
Another problem arose during the "walking" phase of the study. Graduate students working with Rodriguez walked with the study participants once a week and took baseline measurements. But some parents began dropping off the kids every day.
"The parents were using us and our lab space like we were some sort of day care-center," said Rodriguez. "I had to remind them that part of this study was about building support systems and creating behaviors that reinforce good diet and exercise habits, and not about trying to use my grad students as babysitters."
Some parents apologized and resumed taking an active part in walking with their children. One went as far as buying a treadmill for their son. Another even reported that a neighborhood walk group had formed around their daily walks. But many parents let the walking part of the study fall by the wayside. In the end, of the 25 children enrolled, only 16 completed the entire study. Moderation in all things The data generated by the participants who completed the study indicated that protein turnover began to slow dramatically during the diet-only phase of the program even though the children's calories were being cut only moderately. However, the children who had regular walking added to their diets soon had their turnover rates return to near base-line levels.
"There was something about this regular physical activity that stimulated more efficient protein turnover," Rodriguez said. "The data indicated that a stand-alone diet, even a moderate one, needs to be combined with regular activity to be safe for children."
Rodriguez reinforced that both the diets and exercise should remain moderate. She and Ebbeling determined that incurring a deficit of about 250 calories per day will not significantly affect protein turnover. Daily deficits above 500 calories become more problematic.
"The kids put this weight on a couple of pounds a week and that's the only safe way to take it off," she said.
The study paved the way for Rodriguez to receive a grant from the U.S.D.A. to initiate further examination of protein usage in healthy children and the effects of physical activity.
"Odd as it may seem, there's been very little data gathered on this," she said. "The current U.S.D.A. protein recommendations for children are based on extrapolations generated from figures we have on adults and infants. So doing more work in this area is important, and I'm very excited to see what we find."
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