Initial BMI predicts overweight/obesity in children

Baseline body mass index (BMI) and, to a lesser extent, school socioeconomic status are associated with subsequent weight status in schoolchildren, according to a study. Lifestyle behaviours show a lower effect as compared with prior BMI, but children with a healthier lifestyle have a reduced risk of overweight and obesity at follow-up.

“Programmes that aim at preventing the onset of overweight and obesity need to be a priority given the existing difficulties to reverse this condition later in life,” the researchers said.

The main predictors of overweight/obesity in children were baseline BMI (odds ratio [OR], 6.46, 95 percent CI, 4.56–9.17) and school socioeconomic level (OR, 2.12, 1.16–3.86). [Eur J Clin Nutr 2019;73:1299-1306]

At follow-up, the risk of overweight/obesity was lower among children with no savoury snacks consumption (OR, 0.22, 0.07–0.69) or with frequent sports/dancing clubs attendance (OR, 0.41, 0.19–0.88). On the other hand, children with poor fruit intake were at higher risk of overweight/obesity (OR, 2.16, 1.23–3.78).

“Our findings are in agreement with previous literature that showed the strong ability of weight status in childhood to predict weight status in later childhood or adolescence,” the researchers said. [Prev Med 2017;100:229-234; Arch Dis Child 2017;102:915-922; Am J Clin Nutr 1994;59:955-959]

In another study, Chen and colleagues reported that elementary US schoolchildren tended to remain in the same weight category over time. [Pediatr Obes 2016;11:88-94]

Other studies have shown the apparent development of BMI trajectories early in childhood, with age 5 years being identified as critical for the onset of overweight/obesity. [Nutr Diabetes 2016;6:e198; J Epidemiol Community Health 2014;68:934-941; Arch Pediatr Adolesc Med 2011;165:993-998]

“However, the association between baseline BMI and subsequent weight status was stronger with the prevalence of overweight and obesity at follow-up than with the risk of becoming overweight or obese,” the researchers said.

“This made us to hypothesize that other factors in addition to initial BMI may also be relevant predictors of future weight status among children who were not overweight or obese at baseline,” they added.

In cluster analyses involving Australian children, findings showed that television viewing while consuming energy-dense food and drinks increased the risk of overweight/obesity. Another study also found a significant association between hours of daily television viewing and subsequent weight status. [Int J Obes 2015;39:1079-1085; Prev Med 2017;100:229-234]

The current study included 2,755 Irish children, aged 6–10 years at baseline (53.7 percent girls), participating in the Childhood Obesity Surveillance Initiative. The researchers measured height and weight and calculated the BMI.

Overweight/obesity were defined according to the International Obesity Task Force cutoffs. Prevalence of overweight/obesity at baseline and follow-up, incidence of overweight/obesity, and changes in BMI over time were computed. A questionnaire was completed by parents to identify lifestyle indicators. Multivariate mixed logistic regression models were used to assess predictors of overweight/obesity.

“Longitudinal studies focusing on the factors linked to weight gain at early ages should be a priority to identify potential intervention areas,” the researchers said.