The World Health Organization (WHO) has been expressing its concern about the sustained increase in overweight and obesity among children all over the world for years. More than 390 million children and adolescents aged 5 to 19 and 37 million children under 5 were overweight in 2022. According to the WHO, being overweight in childhood and adolescence is associated with a higher risk of contracting diseases like type 2 diabetes and cardiovascular diseases at an early age. It also has adverse psychosocial consequences, and affects academic performance and quality of life.

Obesity is considered a chronic multifactorial disease, i.e. with many causes, in both children and adults. These causes all involve an imbalance between calorie intake (food consumed) and calorie expenditure (physical activity), resulting in excess weight. Understanding the population's eating habits (and the reasons for them) and promoting healthier diets and increased physical exercise is therefore crucial for preventing overweight and obesity and the other problems they cause. The data currently suggest that we do not seem to be moving in the right direction.

A study led by the FoodLab research group at the Universitat Oberta de Catalunya (UOC), in collaboration with the Public Health Agency of the Government of Catalonia, and published in open access format in the Nutrients journal concludes that the vast majority of school-aged children in Catalonia eat unhealthy snacks, with lots of sugars and ultra-processed products. The results are consistent with those recorded by other studies elsewhere in Spain and in other developed countries.

After analysing 2,163 snacks from 734 Catalan families with children aged from 3 to 12 years old, the study concluded that 42% of the snacks were sandwiches, followed by pastries (24%), fruit (14%) and a combination of fruit and pastries (6%). Only 22% of the snacks recorded could be considered healthy and met the recommendations of health authorities and child nutrition experts. Furthermore, the nutritional quality of schoolchildren's snacks declines as they get older.

"Although we have not studied the effects of these diets in this research, the scientific evidence tells us that a recurrent nutritional imbalance over time can have short- and long-term consequences for health, and can affect growth and development," explained Nadia San Onofre, a FoodLab researcher and professor in the UOC's Faculty of Health Sciences. "It is essential to develop food education programmes to improve the quality of snacks from early childhood onwards, and to consider it an opportunity to change the daily dietary needs of children in Spain."

Snacks have only been studied to a limited extent, but the research done to date has found that they are among the types of everyday food intakes that usually contain the highest proportion of unhealthy ultra-processed foods. Meanwhile, research into the nutrition of European school-age children and adolescents points to a decline in the quality of their diet due to their increased consumption of refined cereals, pastries, fast food and sugary drinks, among other foods.

Similar studies at the international level point to the same trends. For example, a study published in 2018 on the snacks of students aged between 4 and 13 years old in Australia, China, Mexico and the United States found differences in the frequency of consumption, and in the energy and nutritional contribution of the food consumed, but in overall terms identified high levels of added sugars and saturated fats in the children's snacks.

The study led by the FoodLab group, which is the result of three master's degree final projects carried out by students on the University Master's Degree in Nutrition and Health at the UOC, also focuses on the tools and challenges needed to improve the nutritional quality of snacks (and children's diets in general), as well as food sustainability. The recommendations in this study include:

• Ensuring that the diet includes a wide variety of fresh or minimally processed plant foods, such as fruits, vegetables, legumes, whole grains, nuts and olive oil, and prioritizing those that are seasonal and locally produced.
• Moderate consumption of foods high in protein, such as fish, eggs, and above all, meat. Dairy products should be consumed without any added sugars.
• Eating fewer foods that are rich in added sugars, fats and salt, and particularly ultra-processed products, pastries, biscuits, sugary drinks and sausages.
• Always drinking water as the main beverage.

"Knowing what to eat is one thing, but knowing how to eat it is another. And that is where planning is important, for both meals and when shopping for food," explained Nadia San Onofre. "Promoting healthy and sustainable habits during childhood requires a cooperative effort that needs to involve families, schools, public health agencies and other institutions in the community, and even the food industry." According to the researcher, children need to be engaged in the kitchen to encourage them to accept different foods, and it is important to adopt healthy habits as adults and to provide models for children, and to offer a variety of seasonal vegetables and fruits as snacks.

"It is also worth remembering that eating habits are determined by factors that are external to the individual," concluded San Onofre. "For example, we must demand that food advertising aimed at children is subject to regulation, because it has proven to be a very effective measure in improving their eating habits, and there must be healthy and affordable alternatives in eating environments near schools. Educational institutions also need to offer food education from an early age, so that kids acquire the knowledge and skills that enable them to make healthy food choices throughout their lives.

This research by the UOC helps achieve United Nations Sustainable Development Goal (SDG) 3: Health and well-being

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