These Two ‘Clock Genes’ May Influence Childhood Obesity

Parents may tell pediatricians that their toddler devours multiple slices of pizza at birthday parties while other kids pick at their plates.No single study explains every nuance of early childhood eating habits, but new research from the University of Guelph offers a key clue: Children with specific variants in “clock genes” — the parts of DNA that regulate cells’ 24-hour circadian cycles — may eat more calories and less protein than their peers.The findings could lead to new precision nutrition strategies for preventing childhood obesity, said study author David W.L. Ma, PhD, professor of human health sciences at the University of Guelph in Guelph, Ontario, Canada. They also reinforce the importance of a simple, if sometimes elusive, habit: getting a good night’s sleep.“We’re advancing our understanding of the differences in the genes that regulate sleep so that we can then better manage our expectations and develop strategies to help families and individuals achieve the health that they desire,” he said.How Clock Genes Affect Kids’ DietsResearchers analyzed saliva samples from 168 children, aged 2-6 years, focusing on single-nucleotide polymorphisms (SNPs) — variations in a single DNA building block — across eight clock genes linked to diet or obesity in prior adult studies. To collect dietary data, researchers had the parents recall what their children ate over the preceding 24 hours.Statistical analysis revealed that two SNPs were associated with distinct eating behaviors:More calories: Children with the CRY2 variant (rs11605924-A) consumed an average of 118 more calories per day than their peers. While that may seem minor, an extra 100-plus calories daily can add up to cause significant weight gain over time, Ma said.Less protein: Children with the NR1D1 variant (rs2314339-T) consumed 2.4% fewer daily calories from protein. This finding suggests potential genetic influences on appetite and food preferences.While the exact mechanisms remain under study, prior research points to a few possibilities. Beyond regulating sleep and wake cycles, clock genes help control body temperature and metabolism, Ma said. There is also the late-night snack factor: Children — and adults — who stay awake longer simply have more opportunities to graze.More research is needed to determine whether sleep differences, metabolic differences, or a combination of the two drive overeating, said Ma.Uncovering the Roots of Childhood Obesity This study was the first to explore the association between clock genes and eating behavior in kids younger than 6 years. Studies like this one bolster understanding of the biological differences that influence early childhood eating behavior, said Kristen E. Boyle, PhD, MS, professor of pediatrics at the University of Colorado Anschutz in Aurora, who was not involved with the study.“It reinforces this idea that obesity doesn’t necessarily just appear through lifestyle alone, that there are other factors that may be contributing,” said Boyle. Genetics, prenatal exposures, family environment, and food access can all influence eating habits from a young age.“While we do have some control over obesity, there are a lot of other factors that we may not necessarily be able to control, like our biology and our environment,” she said.Larger, interventional studies — because this one was a cross-sectional study — could help reveal how nutritional choices interact with underlying genetics.Why Healthy Habits Matter EarlyMa’s team initiated this research to explore pediatric obesity prevention as a foundation for long-term health.“When children are overweight or obese, that condition persists into adulthood, which then increases risk for diabetes, heart disease, and cancer and then reduces healthspan and longevity,” said Ma.Early childhood is the ideal time to start healthy eating and sleeping habits that stick.“Establishing routines early in life is so much easier than later in life,” said Ma. “It may be hard in the beginning, but through a bit of persistence and tenacity, these simple, healthy habits can be readily established.”Clinicians can refer parents to age-specific Dietary Guidelines for Americans and the American Academy of Sleep Medicine’s guidelines for pediatric sleep.Ma noted that parents shouldn’t stress over optimizing every meal or every disrupted night — parenting is challenging enough. Instead, focus on the long run, where consistent sleep and nutrition habits yield the biggest payoff.Ma reported receiving funding from the Canadian Institutes of Health Research and Heart and Stroke Foundation of Canada. Boyle reported receiving funding from the National Institutes of Health.