March 25 (HealthDay News) -- Ever wonder why your children will eat only a few bites of dinner but have no problem scarfing down a big bowl of ice cream?
Blame it on their growing bones.
New research suggests that children who are growing rapidly have a higher preference for sweets than children growing at a slower rate.
Researchers gave 143 children ages 11 to 15 sugar-water and orange Kool-Aid with increasing levels of sweetness. Then they classified the children into two groups: high preference or low preference for sweetness.
They found that children who had the highest levels of a biomarker for bone growth (type I collagen cross-linked N-telopeptides) in their urine were most likely to be in the group that liked the sweetest drinks.
"It's been known for a long time that children have an incredible sweet tooth -- 'Give me Cocoa Puffs and add more sugar,' " said Susan Coldwell, an associate professor of dental public health sciences at the University of Washington and lead author of the new study. "They are using a lot of calories during growth, and the body is responding to that by an increased sweet preference."
Children across cultures have shown a preference for higher levels of sweetness in their foods than have adults. And researchers have wondered whether the preference could be explained by biological or social factors, such as children not having been exposed to as many foods as adults or not yet feeling the pressure to avoid junk food to stay thin.
While there could be multiple reasons children choose cupcakes over spinach, they might be driven to consume sugar because their young bodies can efficiently convert it into energy to fuel growth, Coldwell said.
Yet some researchers said the study does not prove that rapid growth is the cause of the sweet preference.
"It is a provocative theory that the body in some way craves sweets in order to get adequate calories for growth," said Lona Sandon, a registered dietician and an American Dietetic Association spokeswoman. "But the study does not prove cause and effect, and the mechanism of this theory is unknown."
In the study, the researchers also tested for biological factors associated with puberty, including sex hormones, and found that they were not associated with sweet preferences. The findings were published in the March issue of Physiology & Behavior.
What does all of this mean for parents who are trying to combat their child's inner Cookie Monster?
Childhood obesity is a growing problem in the United States, and the wide availability of high-calorie, processed snack foods isn't helping. In the study, 40 percent of the participating children were overweight or at risk of being overweight.
About 33 percent of U.S. children ages 6 to 11 are overweight, as are 34 percent of teens, according to the U.S. Centers for Disease Control and Prevention. The agency defines overweight as having a body mass index (BMI, a ratio of weight to height) in the 85th percentile or above for a child's height and age.
Parents can try offering fruit, which can be sugary but also nutritious and low in calories. With vegetables, Coldwell suggested, offer sweet teriyaki sauce or raspberry salad dressing for dipping.
And, if children still refuse to eat a particular vegetable, continue to offer it, said Jennifer Williams, associate director of the Center for Childhood Obesity Research at Penn State University.
Research has shown that children may need to be exposed to a food 15 times before they're willing to accept it, she said.
Parents should also remember that a time will probably come when a child can pass the candy aisle without hounding you.
"People worry a lot about their kids having this big sweet tooth," Coldwell said. "One thing we can reassure parents is that kids do have a natural developmental downward shift in preference for sweets. Tastes do change in puberty."
The Nemours Foundation has more on encouraging healthy eating in children and teens.
SOURCES: Susan Coldwell, Ph.D., associate professor, dental public health sciences, University of Washington, Seattle; Lona Sandon, R.D., assistant professor, clinical nutrition, University of Texas Southwestern Medical Center at Dallas, and spokeswoman, American Dietetic Association; Jennifer Williams, Ph.D., associate director, Center for Childhood Obesity Research, Penn State University, University Park; March 2009, Physiology & Behavior