Feb. 3, 2025 – During the two quick years when a child is considered a preschooler, a diet high in ultraprocessed foods may put them at risk of developing overweight or obesity by the time they start kindergarten.
Three-year-olds in Canada who ate more ultraprocessed foods than their peers were more likely to have weight-height combinations or skin-fold thickness measurements that are signs of overweight or obesity by age 5.
The term ultraprocessed food applies to obvious items like soda and chips, but some parents may be surprised to learn that the category also includes such things as flavored yogurt and commercially made whole-grain bread.
The study was published Friday in JAMA Network Open.
“We saw that ultra-processed foods contributed to almost half of a child’s total daily energy intake,” said Kozeta Miliku, MD, PhD, assistant professor of nutritional sciences at the University of Toronto’s Temerty Faculty of Medicine, according to a news release, which noted that the effects of ultraprocessed food appeared to be sex-driven because stronger effects were observed in boys.
For the study, ultraprocessed foods were defined as being industrially produced and containing ingredients like emulsifiers, preservatives, and artificial colors and flavors. The foods are considered “shelf stable but nutritionally imbalanced” and “pose a public health crisis worldwide,” the researchers wrote. They noted that the risk of obesity from ultraprocessed foods in adults has already been established, but its link to childhood obesity hasn’t been clear in previous research.
The team analyzed data about what 2,217 Canadian 3-year-olds ate – according to their caregivers – and linked that information to the children’s height, weight, waist circumference, and skinfold thickness measurements that were taken when the kids were 5 years old.
On average, the 3-year-olds ate 1,518 calories per day, although the range among children was 1,239 to 1,858 per day. The study wasn’t able to establish what happens in a child’s body that may link ultraprocessed food intake to an increased risk of obesity or overweight. The researchers did, however, look specifically at children’s differences in sodium, saturated fat, and sugar intake – which they called “nutrients of concern” – and didn’t find a specific link to increased risk of obesity or overweight.