Excess sugar in the diet is a known risk factor for developing metabolic disorders, including obesity and diabetes. Researchers have now found that the source of sugar matters more than the amount when it comes to the development of obesity in children.

The study results presented at the European Congress on Obesity revealed that the total amount of sugar consumed while being a toddler did not affect the weight of the child at the age of 10 or 11.

The researchers also found that children who get a higher proportion of their sugar from fruits and unsweetened liquid dairy products such as milk and buttermilk had a reduced risk of developing overweight or obesity. However, those getting a greater proportion of sugar from sweet snacks, confectioneries, sweetened milk, and yogurt drinks, have a higher risk of gaining weight.

"The high consumption of sugary foods is considered a risk factor for childhood overweight and obesity and so children are advised to consume less sugar-rich foods, such as confectionery, cakes, and sugar-sweetened drinks, and eat more fruit and unsweetened dairy products, such as milk and yogurt," lead researcher Junyang Zo said in a news release.

"But while fruit and unsweetened dairy products are considered healthy, they contain high amounts of intrinsic sugars – sugar that occurs naturally in the food, rather than being added. We wanted to know if the source of sugar, added versus intrinsic, as well as the amount, affects the likelihood of developing overweight or obesity," Zo said.

The study was based on data from an ongoing longitudinal study involving 891 children born in the northern Netherlands, between April 2006 and April 2007. To understand the association between obesity and the total amount of sugar intake in early childhood and the intake of sugar from different sources on weight, the researchers used a food intake questionnaire filled in by the parents of the participants.

The questionnaire measured the total daily sugar intake of each participant, as well as their intake of sugar from 13 food groups at the age of three. The height, weight, and BMI scores of the participants were calculated at various stages. The change in BMI scores between the ages of 3 and 10/11 years and weight status at the ages of 10 and 11 were noted.

The researchers noted that the average daily sugar intake was 112g, which made up around a third of the total daily energy intake when the participants ate 1,388 calories. The study identified the main sources of sugar in the diet as fruits, dairy products, sugar-sweetened beverages, and sugary snacks.

"At 10/11 years of age, 102 children with normal weight at the age of 3 had developed overweight or obesity. Total sugar intake at 3 years was not related to BMI Z-score, weight gain, or weight status at 10/11 years. However, a higher intake of sugar from sugary snacks was related to a higher BMI Z-score of 10/11," the news release stated.

The study did not investigate the reasons behind the varying effects of different foods on weight. However, researchers believe that the slower release of sugar from whole fruits compared to sugary snacks, along with differences in how these sugars interact with the body, might explain the observed mechanisms.

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