Obese parents increase kids' risk of being overweight
Sensitive disposition and lack of sleep also cited as risk factors in new study
The factor that puts children at greatest risk of being overweight is having obese parents, according to a new study by medical school researchers. By identifying the risk factors that lead to childhood obesity, the researchers hope to pave the way toward preventive measures.
“The findings of this study suggest that at-risk children may be identifiable in the first few years of life,” said W. Stewart Agras, MD, professor emeritus of psychiatry and behavioral sciences, whose team assessed both established and hypothesized risk factors in a study published in the July issue of the Journal of Pediatrics.
The Centers for Disease Control and Prevention has established two categories of overweight children: those who are “at risk,” meaning they have a body mass index (a measure of body fat based on height and weight) above the 85th percentile, and those considered “severe,” meaning a BMI above the 95th percentile. In the most recent survey, more than 30 percent of children were considered at risk. And the prevalence of severely overweight children, 15 percent, has doubled during the past 20 years.
According to the American Obesity Association, pediatricians are reporting more frequent cases of obesity-related diseases such as type-2 diabetes, asthma and hypertension — diseases that once were considered adult conditions.
While numerous risk factors for overweight children have been identified — including low socioeconomic status, higher birth weight and lack of physical activity — few studies have examined these factors in infancy and early childhood.
“It's important to identify risk factors because they may provide a way to alter the child's environment and reduce the chance of becoming overweight,” Agras said.
During the exploratory study, Agras' team began tracking 150 children and their parents upon the child's birth. Attributes and behaviors were assessed until the child was 5 years old and were then used to predict whether the child would be overweight at 9.5 years. Monitored areas included parent weight, infant weight, parent eating behaviors, child eating behaviors, child activity, child temperament, child sleep time and parents' concerns about their child's weight.
The researchers found that 25 percent of the children were in the 85th percentile of BMI at 9.5 years of age, including 9 percent that were in the 95th percentile. They also found that 48 percent of children with overweight parents became overweight, compared with 13 percent of those with normal-weight parents.
Agras said parental obesity represented the most potent risk factor, a finding that confirms previous observations, and the connection between overweight parents and overweight children is likely due to a combination of genetics and family environmental influences.
He also noted that a child's temperament altered the effect of a parent's obesity; 46 percent of children with a sensitive disposition and an overweight parent became overweight, compared with 19 percent of children without this disposition.
Temperament also played a role for children with normal-weight parents. Agras said it is likely that parents with emotional children feed them to reduce the frequency of tantrums instead of using non-food methods.
“It's probably not a good idea to use food as a calmer,” he said. “If we can identify kids with difficult temperaments, we could educate parents not to use food as a reward.”
Other significant risk factors were low parental concerns about their child's thinness and less sleep for the children. On average, overweight children got 30 fewer minutes of sleep than normal-weight children. The finding on sleep replicates previous findings but is not well understood, Agras said.
“We don't know at all how this works,” he said. “One possibility is that the kids sleep less because they're less active during the day.”
Co-authors include Lawrence Hammer, MD; Fiona McNicholas, MD; and Helena Kraemer, PhD. Hammer and Kraemer are both at Stanford; McNicholas is now at University College in Dublin, Ireland.