Do Ultra-Processed Foods Affect a Child's Health?
Key findings: 60-second read
- Ultra-processed food (UPF) consumption is highly prevalent among children and adolescents - one Brazilian study found 75.4% of adolescents had excessive UPF intake, with UPFs contributing 47% of total energy in young children.
- UPF consumption is associated with higher BMI and obesity risk - adolescents in the highest UPF consumption quintile had significantly higher mean BMI and increased odds of overweight (OR=1.52) and obesity (OR=2.74).
- Physical inactivity and UPF consumption cluster together - the most frequent combination of risk factors involved unhealthy diet (high UPF) and insufficient physical activity.
- Skipping breakfast is a key behavioural marker - associated with childhood obesity and higher UPF consumption, while regular breakfast eating is linked to other protective health behaviours.
- UPF consumption is linked to cardiometabolic risk - including elevated cholesterol, triglycerides, and hypertension, as well as oral health outcomes through added sugar intake and systemic inflammation.
Childhood and adolescence are critical periods for establishing health behaviours that track into adulthood. What children eat, how active they are, and the habits they form during these years have profound implications for their long-term health trajectory.
A 2023 systematic review synthesised evidence from 19 observational studies involving approximately 300,000 children and adolescents across Brazil, Iran, China, Nepal and Singapore. The review examined associations between ultra-processed food (UPF) consumption and health outcomes in young populations.
The findings are concerning. Across multiple countries and cultural contexts, a consistent pattern emerges: high UPF consumption is associated with obesity, cardiometabolic risk factors, physical inactivity, and oral health problems. Importantly, these risk factors do not occur in isolation but cluster together, creating compounded health risks during critical developmental windows.
"The most frequent combinations of risk factors in children and adolescents involved an unhealthy diet, with regular consumption of ultra-processed foods to the detriment of a diet based on fresh or minimally-processed foods and insufficient levels of physical activity."
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What are ultra-processed foods? (NOVA classification)
According to the NOVA classification system, which groups foods according to their level and purpose of industrial processing, ultra-processed foods are industrial formulations made entirely or mostly from substances extracted from foods (oils, fats, sugar, starch, protein isolates), derived from food constituents (hydrogenated fats, modified starches), or synthesised in laboratories (flavour enhancers, colourants, preservatives).
These products are designed to be highly palatable, convenient, shelf-stable, and inexpensive to produce. Examples include soft drinks, packaged snacks, breakfast cereals with added sugars, reconstituted meat products, instant noodles, and many ready-to-heat meals.
Several mechanisms may explain the relationship between UPF consumption and adverse health outcomes: nutritionally unbalanced profiles (high in free sugars, sodium, saturated and trans fats, low in fibre and bioactive compounds); high energy density and glycaemic load; disruption of neural and hormonal signals regulating hunger and satiety; and aggressive marketing targeted at children.
Study characteristics and population
The review included 19 observational studies (cross-sectional, longitudinal, and cohort designs) published without date restrictions, identified from Scopus, Web of Science, PubMed and Scielo databases. The studies encompassed approximately 300,000 children and adolescents, with sample sizes ranging from 40 to 173,310 participants.
Geographic distribution of the included studies:
- Brazil: 13 studies
- Iran: 2 studies
- China, Nepal and Singapore: 1 study each
Key finding on prevalence: One study of 16,324 Brazilian adolescents found the prevalence of excessive UPF consumption was 75.4% (95% CI: 73.3-77.3), with the highest consumption in the Southeast region and lowest in the North region. Only 2.9% of adolescents had no risk behaviours, while 38.0%, 32.9%, 9.4% and 1.8% accumulated two, three, four and five risk factors respectively.
Dietary patterns and UPF consumption
A temporal trend analysis of Brazilian school adolescents (2009, 2012, 2015) indicated that regular consumption of processed and ultra-processed foods was the second most prevalent risk factor for chronic diseases, second only to insufficient physical activity. Notably, the authors observed a trend toward decreased participation of UPFs in the diet over time, accompanied by increased irregularity in consumption of fresh and minimally-processed foods.
In Nepal, a study of 1,108 adolescents found that 41% had unhealthy eating habits - more than half did not consume vegetables and fruits five or more times daily, and more than half included soft drinks at least weekly. Overall, 40.7% of adolescents had co-occurring NCD risk factors, with unhealthy diet being a primary contributor.
Studies from Brazil and Singapore revealed that a significant proportion of children and adolescents do not consume fresh foods (fruits, vegetables) or minimally-processed foods (rice, beans) daily. In contrast, the prevalence of daily UPF consumption among adolescents in São Paulo was 64%, with soft drink consumption at 16.2% in 2017. The same study found a negative association between participation in food purchases and soft drink consumption, while regular cooking was positively associated with consumption of rice and beans.
An analysis of lunch boxes from 44 children in Diamantina, Brazil, found that UPFs were predominant: yoghurt (55.9%), boxed chocolate milk (41.2%), sandwich cookies (50%) and packaged snacks (35.3%).
One study from Pernambuco, Brazil, showed high consumption of fruits (66.7%) and vegetables (45.5%) among schoolchildren aged 5-10 years, but also high UPF consumption: 33% consumed hamburgers or cold cuts, 63% consumed sandwich biscuits, sweets or candy, and 83% consumed sweetened beverages.
"The daily consumption of ultra-processed foods was 64% and of soft drinks 16.2% among adolescents in São Paulo. The diet of adolescents in this group still does not fully meet the recommendations."
Overweight and obesity
A study by Louzada et al. (2015) with 7,534 Brazilian individuals aged 10-19 years found that adolescents in the highest quintile of UPF consumption had a higher mean BMI (adjusted coefficient: 0.84; 95% CI: 0.42-1.42) and greater odds of being overweight (adjusted OR = 1.52; 95% CI: 0.75-3.07) or obese (adjusted OR = 2.74; 95% CI: 0.78-9.60) compared to those in the lowest quintile.
Analysis of SISVAN data from Pernambuco, Brazil, covering 3,663 children across all health regions, revealed that 33.84% were overweight or obese according to the BMI-for-age index, concurrent with high UPF consumption.
Among schoolchildren in Minas Gerais, Brazil, BMI ranged from 18.63 to 32.08 kg/m², with a median of 21.8 kg/m². Among students classified with excess weight, 40% were overweight and 60% were obese. The study also found that consumption of minimally-processed foods was inversely associated with excess weight in adolescents.
According to the World Obesity Atlas (2023), by 2035 approximately one-third of children and adolescents in Brazil may live with obesity. In 2020, the prevalence of overweight and obesity was 12.5% among girls and 18% among boys. Projections indicate these figures could reach 23% and 33% respectively in coming years.
The review authors concluded: "The findings of the present study confirm the role of ultra-processed foods in the obesity epidemic in Brazil."
Cardiovascular outcomes
Cardiovascular diseases represent approximately 50% of deaths caused by chronic NCDs in middle- and low-income countries. Risk factors for early cardiovascular disease are increasingly present during growth phases, with smoking and alcohol consumption as primary variables, along with overweight and obesity.
Analysis of data from 101,607 adolescents in the 2015 Brazilian National School Health Survey (PeNSE) revealed a strong correlation between alcohol consumption and smoking, which co-occurred in 8 of 13 identified clusters.
In a study of schoolchildren in Minas Gerais, biochemical analysis revealed elevated total cholesterol (mean = 178.6 mg/dL; SD = 36.9) and triglycerides (mean = 100.3 mg/dL; SD = 39.5) compared to reference values (<170 mg/dL and <75 mg/dL, respectively).
Zhao et al. (2021) evaluated 895 Chinese adolescents aged 15-19 years and found that 8.4% and 14.1% reported pre-hypertension and hypertension, respectively. A two-class model identified a healthy lifestyle pattern (65.8%) and an unhealthy pattern (34.2%). Significant differences in waist circumference were observed between the two classes (70.5 vs 69.1 cm; p = 0.044).
The authors note that although several indicators related to chronic NCDs (overweight, obesity, adverse cardiovascular and metabolic conditions) are often associated with UPF consumption in adults, the available information for children and adolescents is less clear and warrants further investigation.
Physical activity and sedentary behaviour
The 2015 Brazilian National School Health Survey (PeNSE), with 16,324 participants, revealed that 75.2% of schoolchildren were classified as inactive or insufficiently active, with only 24.8% meeting the minimum physical activity recommendation of approximately 300 minutes per week.
The Study of Cardiovascular Risks in Adolescents (ERICA), conducted nationally in 2013-2014, found the prevalence of leisure-time physical inactivity was 54.3% (95% CI: 53.4-55.2), substantially higher among females (70.7%) compared to males (38.0%).
Regarding sedentary behaviour defined as time spent in static activities with low energy expenditure (sitting or lying positions), Silva et al. (2021) identified nine independent factors associated with excessive UPF consumption, including daily sitting time exceeding four hours, eating while watching television for more than four days per week, daily television viewing exceeding three hours, and breakfast frequency less than four days per week.
Research on age-related changes in healthy behaviours indicates that as age increases, healthy practices decrease. Physical activity tends to decline between ages 11 and 15, influenced by independence, exposure to new practices and environments, and socioeconomic conditions.
Araújo et al. (2022), analysing data from 2009, 2012 and 2015 with Brazilian schoolchildren, concluded that insufficient physical activity and regular UPF consumption were the most prevalent risk factors, with the most frequent correlation being unhealthy diet combined with insufficient physical activity.
"Physical inactivity and a sedentary lifestyle constitute risk factors for the development of chronic NCDs. The hypothesis of the association of physical inactivity as one of the risk factors for chronic NCDs that occur simultaneously in childhood and adolescence has been proven."
Oral health and chronic NCDs
Periodontal diseases and dental caries are themselves considered chronic NCDs. The literature demonstrates a consistent relationship between these conditions and other chronic NCDs, including obesity.
Carmo et al. (2018) assessed the association of added sugar consumption with the burden of chronic oral diseases (COD) among adolescents, considering obesity and systemic inflammation pathways. Results indicated that greater added sugar consumption, higher interleukin-6 (IL-6) levels (elevated by excessive sugar intake and obesity), and lower socioeconomic status were related to higher COD burden values.
Obesity was not directly associated with COD burden; however, excess weight indicated an indirect association through higher IL-6 levels (standardised coefficient = 0.232, p = 0.001). Adolescents with obesity had higher serum IL-6 levels compared to those with normal weight.
The authors concluded that dental caries and periodontal diseases are interconnected and related to sugar consumption, obesity and systemic inflammation, reinforcing WHO recommendations that approaches to chronic NCD prevention must target common risk factors.
The protective role of breakfast
Skipping breakfast was associated with childhood obesity and excess weight in two studies included in this review: one with adolescents in Brazil's Central-West region, and another with Iranian children.
Data from the ERICA study showed that 48.5% of Brazilian adolescents reported having breakfast "almost always or always", while 21.9% did not have this meal. Regular breakfast consumption has been positively associated with other protective behaviours, including sleeping more than eight hours per day and engaging in regular physical activity.
Skipping breakfast is also associated with eating most meals outside the home and not participating in domestic meal preparation. Moreover, skipping breakfast is related to increased consumption of high-energy snacks rich in fats and sugars as a compensatory strategy for meal absence.
Khashayar et al. (2018) found that 32.8% of Iranian students (aged 6-18 years) did not eat breakfast (less than 5 days per week), and identified skipping breakfast as a factor associated with childhood overweight and obesity alongside sociodemographic characteristics, birth weight classification, and family history of obesity.
Silva et al. (2021) identified breakfast frequency of less than four days per week as one of nine independent factors associated with excessive UPF consumption in Brazilian adolescents.
Clustering of risk factors
A key finding of this review is that risk factors for chronic NCDs do not occur in isolation but tend to cluster together in children and adolescents. The most frequent combinations involved unhealthy diet (high UPF consumption, low intake of fresh and minimally-processed foods) and insufficient physical activity.
Ricardo et al. (2021), analysing data from 101,607 adolescents in PeNSE 2015, found that only 2.9% of adolescents had no risk behaviour, while 38.0% accumulated two risk factors, 32.9% accumulated three, 9.4% accumulated four, and 1.8% accumulated five risk factors.
Sena et al. (2017), in a cohort study of 1,716 adolescents from Cuiabá, Brazil, identified sedentary lifestyle (58.1%), insufficient physical activity (49.7%), and skipping breakfast (36.2%) as the most prevalent risk behaviours. The study confirmed the hypothesis that main risk factors for NCDs tend to occur simultaneously in adolescents.
This clustering phenomenon has important implications for intervention design. Addressing single risk factors in isolation is unlikely to be effective; comprehensive approaches targeting multiple behaviours simultaneously are required.
Key insight on clustering: "The most frequent combinations of risk factors in children and adolescents involved an unhealthy diet and insufficient physical activity. The main risk factors for NCDs are frequent and not randomly distributed among Brazilian adolescents."
Limitations of the evidence base
The review authors acknowledge several limitations in the available evidence:
- Only observational studies (cross-sectional, longitudinal, cohort) were included; no randomised controlled trials were available for this age group
- Most studies used self-reported dietary data and secondary data sources, which may introduce recall and social desirability biases
- Studies employed different methodological approaches, limiting comparability
- Some results were considered inconclusive, particularly for this age group
- Studies were concentrated in specific countries (primarily Brazil), with limited geographic diversity
Despite these limitations, the authors note that the evidence consistently indicates associations in the same direction, allowing exploration of the topic and identification of meaningful patterns.
Conclusions and clinical implications
This systematic review discloses associations between ultra-processed food consumption and harmful health outcomes in childhood and adolescence, including overweight, obesity, physical inactivity, cardiovascular risk factors, and periodontal disease.
Children and adolescents across different parts of the world have predominantly unhealthy dietary patterns, with regular UPF consumption displacing fresh and minimally-processed foods. Combined with other risk factors (particularly insufficient physical activity), this pattern contributes to increasing childhood obesity prevalence, high rates of physical inactivity, sedentary lifestyles, and risk for chronic NCD development including cardiovascular disease and dental caries.
Among the most relevant findings is that UPF consumption and associated chronic NCD risk cluster with other unhealthy lifestyle behaviours. Low breakfast frequency and high physical inactivity prevalence are markers of this unhealthy scenario, with proven associations across different contexts.
The review maps current literature and indicates important directions for health promotion actions aimed at preventing and controlling chronic NCDs in young populations. The identification of risk factors and their clustering patterns can inform the construction and improvement of effective interventions for this population, whose developmental period also indicates health outcomes in adult life.
Given the scenario of UPF consumption among children and adolescents and the harmful health outcomes, combined with the scarcity of conclusive scientific studies for this age group, the authors indicate the need for future prospective studies specifically aimed at evaluating these associations.
Clinical implications for physiotherapists and health professionals
While physiotherapists do not typically provide dietary counselling, understanding the relationship between UPF consumption, physical activity, and health outcomes is essential for comprehensive patient care. Children and adolescents presenting with musculoskeletal complaints, fatigue, or poor recovery from injury may have underlying nutritional factors that affect tissue healing and energy availability.
Key implications for practice:
Screening for lifestyle clustering: Clinicians should be aware that unhealthy dietary patterns, physical inactivity, and sedentary behaviour cluster together. Assessment of one domain should prompt consideration of others.
Breakfast as a behavioural marker: Skipping breakfast is associated with both poorer diet quality and lower physical activity levels. This simple question may serve as a useful screening tool for broader lifestyle risk.
Oral health connections: The association between added sugar intake, systemic inflammation, and periodontal disease reinforces the importance of interdisciplinary care and awareness of oral health as a component of overall health.
Long-term trajectory: Risk factors manifested in adolescence tend to persist into adulthood. Early intervention for lifestyle-related health issues in young populations may have substantial long-term benefits.
One key insight from this systematic review
"Children and adolescents across different parts of the world have a predominantly unhealthy diet, with regular consumption of ultra-processed foods to the detriment of a diet based on fresh or minimally-processed foods. Combined with insufficient physical activity, this practice contributes to increasing obesity prevalence, physical inactivity, and risk for chronic non-communicable diseases including cardiovascular disease and periodontitis."
Frequently asked questions
What defines an ultra-processed food?
According to the NOVA classification, ultra-processed foods are industrial formulations made mostly from substances extracted from foods (oils, fats, sugar, starch, protein isolates), derived from food constituents (hydrogenated fats, modified starches), or synthesised in laboratories (flavours, colours, preservatives). They typically contain little or no whole food and are designed to be highly palatable, convenient, and shelf-stable. Examples include soft drinks, packaged snacks, sugary breakfast cereals, reconstituted meat products, instant noodles, and many ready-to-heat meals.
How strong is the evidence linking UPFs to obesity in children?
The review found consistent associations across multiple studies from different countries. One study of 7,534 Brazilian adolescents found that those in the highest UPF consumption quintile had 2.74 times higher odds of obesity compared to those in the lowest quintile. However, the authors note that most evidence is observational and cross-sectional, establishing association rather than causation. Some studies found no significant association, indicating the need for further prospective research.
Why is breakfast consumption relevant to UPF intake?
Regular breakfast consumption is associated with lower UPF intake and other protective health behaviours including adequate sleep duration and regular physical activity. Conversely, skipping breakfast is associated with increased consumption of high-energy snacks rich in fats and sugars as a compensatory strategy. The review identified low breakfast frequency as an independent factor associated with excessive UPF consumption in adolescents.
Do the effects differ between children and adolescents?
The review included both age groups but did not systematically compare them. However, one study noted that as age increases between 11 and 15 years, healthy practices tend to decrease, with physical activity declining and exposure to new risk behaviours increasing. The authors suggest that developmental stage influences both dietary patterns and physical activity behaviours.
What are the implications for clinical practice?
For physiotherapists and other health professionals working with children and adolescents, the key implication is awareness that risk factors cluster. A child presenting with obesity or physical inactivity may also have high UPF consumption, poor breakfast habits, and potentially other risk behaviours. Comprehensive assessment and interdisciplinary referral may be warranted. The review also highlights the importance of early intervention, as risk factors manifested in adolescence tend to persist into adulthood.
As a physiotherapist who works with people of all ages, I see the long-term consequences of lifestyle-related health issues that began in childhood. The child who is physically inactive and consumes a diet high in ultra-processed foods is not simply at risk for obesity; they are at risk for a trajectory of metabolic dysfunction, musculoskeletal problems, and reduced quality of life that extends into adulthood.
This systematic review reinforces what many clinicians have observed: unhealthy behaviours cluster. The child who skips breakfast is more likely to have high screen time. The adolescent who is physically inactive is more likely to consume ultra-processed foods. Addressing these behaviours in isolation is unlikely to be effective.
If you are a parent concerned about your child's eating habits, physical activity levels, or weight, or if you are a young person wanting to understand how lifestyle factors affect your health, I encourage you to speak with a healthcare professional who can provide comprehensive assessment and guidance.
- Grant
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Disclaimer: This information is for educational purposes and does not replace individualised medical, nutrition, or exercise advice. Always consult qualified health professionals for specific health concerns. This blog post summarises a published systematic review (PMC10960188); the original source should be consulted for full methodological details. Individual responses to dietary and lifestyle factors vary.
