A team led by the Barcelona Institute for Global Health (ISGlobal), a centre supported by "la Caixa", has carried out a study to identify lifestyle habits that influence the risk of overweight and obesity in children. Of the behaviours analysed in the study, television watching had the strongest association with overweight and obesity.

The study, published in the journal Pediatric Obesity, was based on data from 1,480 children from Sabadell, Gipuzkoa and Valencia enrolled in the birth cohort of the INMA Environment and Childhood Project, a Spanish research network that studies the role of pollutants during pregnancy and their effects on children. The researchers analysed five lifestyle habits: physical activity, sleep time, television time, plant-based food consumption and ultra-processed food consumption. Parents were asked to complete various questionnaires on the children's lifestyle habits at four years of age. To calculate the health impact of these habits, the researchers measured the children's body mass index (BMI), waist circumference and blood pressure at four and seven years of age.

"Most research to date has focused on the impact of individual lifestyle behaviours rather than cumulative effects," commented Martine Vrijheid, co-leader of the study and researcher in the ISGlobal Programme on Childhood & Environment. "However, it is well known that unhealthy behaviours tend to overlap and interrelate. Our aim in this study was to examine the whole set of lifestyle behaviours with a view to facilitating the development of interventions capable of targeting the determinants of obesity from a broader perspective."

Television Encourages Bad Habits

The study findings showed that children who were less active and spent more time in front of the television at four years of age were at greater risk of being affected by overweight, obesity and metabolic syndrome at seven years of age. The researchers also measured the time spent by the children on other sedentary activities, such as reading, drawing and doing puzzles. However, these activities did not appear to be associated with overweight or obesity.

"When children watch television, they see a huge number of advertisements for unhealthy food," commented ISGlobal's Dora Romaguera, co-leader of the study. "This may encourage them to consume these products." Ultra-processed foods, such as pastries, sweet beverages and refined-grain products, are high in sugar, salt and saturated fat and low in nutritional value. The study showed that high intake of these products at four years of age was associated with a higher BMI at seven years of age.

Moreover, television viewing "discourages physical activity and interrupts sleep time", explained Sílvia Fernández, a post-doctoral researcher at ISGlobal. As the researchers noted, adequate sleep time in early childhood is essential for weight control later in childhood. "Previous studies have shown that 45% of children are not sleeping the recommended number of hours per night," explained Fernández. "This is worrying because shorter sleep time tends to be associated with obesity."

"Identifying habits linked to overweight and obesity in the early stages of life can help us to define preventive strategies against other conditions, such as cardiovascular and metabolic diseases during adulthood," commented Rowaedh A. Bawaked, researcher at the Hospital del Mar Medical Research Institute and lead author of the study. The study concluded that adult health depends on the establishment of healthy lifestyle habits during childhood: limited television time, extracurricular physical activity, getting enough hours of sleep, eating lots of vegetables and avoiding ultra-processed foods.