Will Overweight Children Be Overweight Adults?

A father brings his 2-year-old son to the family doctor’s office with concerns about his child’s weight. He says, “We thought our child was just a good eater, round and healthy. But our son’s teacher weighed and measured him, said that his BMI was too high, and recommended that we talk with the doctor. Do we need to worry that he’ll be overweight as he gets older?”

Over recent decades, population-wide increases in the consumption of calorie-dense foods and beverages, and reduction in physical activity, have dramatically increased the prevalence of obesity in children and adults. Obesity increases the risk of limited physical activity, poor self-esteem, type 2 diabetes, cardiovascular disease, and other serious conditions. Because the morbidity and mortality associated with obesity tend to increase from childhood to adulthood, identifying the best age at which to target obesity prevention interventions is critical.

In this week’s NEJM, Ward et al. present a simulation model to predict the risk of adult obesity at age 35 for the current population of children in the U. S. The authors pooled height and weight data from five nationally representative longitudinal studies that included more than 40,000 children and adults, and simulated growth trajectories, adjusting for secular trends.

Assuming that current trends in childhood obesity continue, the model predicted that 57% of today’s children will be obese at age 35 years. The relative risk of adult obesity increased with age and BMI (from 1.17 for overweight 2-year-olds to 3.10 for severely-obese 19-year-olds). Obese 2-year-olds had a 75% chance of still being obese at age 35 and obese 19-year-olds had an 88% risk. Interestingly, for non-obese children, the risk of becoming obese decreased with age (from 58% at age 2 to 44% at age 19), indicating that avoiding obesity throughout childhood increases the likelihood that a child will not be obese as an adult. The authors conclude that early development of obesity in childhood is a statistically significant risk factor for future obesity in adulthood, especially for children with severe obesity. Therefore, clinical and public health interventions to promote obesity prevention should target early childhood.

Returning to the father’s concern about his overweight 2-year-old, the physician should thank the parent for sharing his concern about his son’s weight and health, and offer to work with the family to get the child on a healthier weight trajectory. Optimally, the health care team — which may include nutritionists, nurses, and community health workers — should chart the child’s height and weight, review his diet and physical activity, and work closely with the family to identify practical strategies to minimize excess calories and boost physical activity. Strategies may include serving milk or water instead of sugar-sweetened beverages, playing daily at the park, and limiting screen time. Above all, parents need the support of health professionals, childcare providers, schools, government programs, and businesses to advocate for and create environments that promote optimal child nutrition and physical activity.

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Karen is a 2017-2018 NEJM Editorial Fellow, Clinical Professor at UC Berkeley-UCSF Joint Medical Program and UC Berkeley School of Public Health, researcher on children’s nutrition and oral health, and member of American Academy of Pediatrics.