Fruit and vegetables are essential for the body to function properly; combined with exercise, they can play an essential role in the fight against obesity. However, they are not necessarily beneficial in all forms. Juices, for example, have been associated with weight gain in children.

So suggests a new study by researchers based in Canada and the United States, which reports a “positive association” between the consumption of 100% fruit juice and body weight in children.

To come to this conclusion, they carried out a systematic review and meta-analysis of 42 studies – 17 involving 45,851 children and 25 involving 268,095 adults. The aim was to assess the association between the consumption of 100% fruit juice and weight gain among children and adults, in comparison with noncaloric beverages.

Published in the journal Jama Pediatrics, the research suggests that daily consumption of a glass or more of fruit juice is associated with weight gain in children.

In detail, the scientists report that each additional serving of 100% fruit juice (one serving being equivalent to 237 ml of the drink) per day was associated with a 0.03 higher body mass index (BMI) in children. In addition, children under the age of 11 gained more weight than adolescents.

“A potential mechanism linking 100% fruit juice to weight gain is the consumption of liquid calories, which has been shown to result in greater weight gain compared with the ingestion of solid calories.

“Compared with whole fruit, 100% fruit juice contains less dietary fibre, leading to the rapid absorption of fructose in the liver,” the researchers explained.

Note, however, that it’s not a question of singling out fruit juices or banning them altogether, but of moderating their consumption and favouring whole fruit. “Our findings are in support of public health guidance to limit consumption of 100% fruit juice to prevent overweight and obesity,” the researchers concluded.