A major study following nearly 5,000 German children and teenagers for 11 years found that eating more ultra-processed foods (like packaged snacks, sugary drinks, and fast food) significantly increases the risk of becoming overweight or obese. Kids who ate the most ultra-processed foods were almost 50% more likely to become overweight and more than twice as likely to develop obesity compared to those who ate the least. The research suggests that reducing ultra-processed food consumption during childhood and adolescence could be an important way to prevent weight problems both now and in adulthood.

The Quick Take

  • What they studied: Whether eating ultra-processed foods (packaged, heavily processed foods with lots of additives) during childhood and teenage years leads to weight gain and obesity
  • Who participated: 4,762 German children and teenagers aged 3-17 years old who were tracked for an average of 11 years, starting with their eating habits and weight measurements at the beginning of the study
  • Key finding: For every 10% increase in ultra-processed food consumption, kids had a 12% higher chance of becoming overweight. Kids eating the most ultra-processed foods had nearly 50% higher odds of overweight and more than double the odds of obesity compared to those eating the least
  • What it means for you: Reducing ultra-processed foods in children’s diets may help prevent weight problems. However, this is one study and other factors like physical activity, overall diet quality, and genetics also matter. Talk to a doctor or nutritionist for personalized advice

The Research Details

This was a longitudinal cohort study, which means researchers followed the same group of children over many years to see what happened to them. At the start, researchers collected information about what the children ate using a food frequency questionnaire (basically asking detailed questions about eating habits) and measured their height and weight. They classified foods using the NOVA system, which divides foods into four groups based on how processed they are—ultra-processed foods are the most heavily processed with added ingredients like preservatives, colorings, and flavorings.

The researchers then followed these children for an average of 11 years, tracking when they developed overweight or obesity. They used statistical models to figure out whether eating more ultra-processed foods was connected to weight gain, while accounting for other important factors like age, sex, family income level, how much exercise kids got, and their starting weight. This approach helps show whether ultra-processed foods themselves might be causing the weight gain, rather than other factors.

This study design is valuable because it follows real children over many years in their normal lives, rather than just looking at one moment in time. This makes it stronger evidence than studies that only look at kids once. The long follow-up period (11 years) means researchers could see actual weight changes happen, not just guess about future risk. By measuring diet at the beginning and tracking weight changes afterward, the study can suggest that ultra-processed food consumption might come before weight gain, which is important for understanding cause and effect.

This study has several strengths: it’s a large sample of nearly 5,000 children from a national German health survey, it followed people for over a decade, and it adjusted for multiple other factors that could affect weight. However, diet was measured using questionnaires asking people to remember what they ate, which can be imperfect. The study shows association (connection) between ultra-processed foods and weight gain, but cannot definitively prove that ultra-processed foods alone cause obesity, since many factors influence weight. The results are from Germany and may not apply equally to all countries or populations.

What the Results Show

The study found a clear connection between eating more ultra-processed foods and developing weight problems. When researchers looked at each 10% increase in ultra-processed food consumption, children had a 12% higher chance of becoming overweight. This might sound small, but it adds up—a child who increases their ultra-processed food intake by 50% would have roughly a 60% higher risk of overweight.

When comparing children who ate the most ultra-processed foods to those who ate the least, the differences were even more dramatic. Kids in the highest consumption group had 49% greater odds of becoming overweight. For obesity specifically, the risk was even higher—children in the third-highest consumption group had more than double the odds of developing obesity (132% higher), and those in the highest group had 74% higher odds.

These associations remained strong even after researchers accounted for other important factors like how much physical activity kids got, their family’s income level, and their starting weight. This suggests that ultra-processed food consumption itself appears to be an important factor in weight gain, independent of these other influences.

The study found that the relationship between ultra-processed foods and obesity risk wasn’t perfectly straight-line—the third consumption group actually had higher obesity risk than the fourth group. This suggests the relationship is complex and other factors may play a role. The consistent findings across different age groups (3-17 years) suggest this is a concern throughout childhood and adolescence, not just at certain ages.

This research adds important evidence to a growing body of research showing that ultra-processed foods are linked to weight gain and obesity. Previous studies have shown similar connections in adults, but this study is valuable because it focuses specifically on children and adolescents with a very long follow-up period. The findings align with other research suggesting that ultra-processed foods may contribute to obesity through multiple mechanisms, including being high in calories, low in nutrients, and potentially affecting how full people feel.

The study measured diet using questionnaires where people remember what they ate, which can be inaccurate. People may forget foods they ate or not remember portion sizes correctly. The study was conducted in Germany, so results may not apply equally to other countries with different food systems and eating patterns. While the study shows association between ultra-processed foods and weight gain, it cannot prove that ultra-processed foods directly cause obesity—other unmeasured factors could play a role. Additionally, some children dropped out of the study over the 11 years, which could affect results if those who left were different from those who stayed.

The Bottom Line

Based on this research, reducing ultra-processed food consumption appears to be a reasonable strategy for helping prevent weight gain in children and teenagers (moderate confidence level). Parents and caregivers might consider replacing some ultra-processed foods with whole foods like fruits, vegetables, whole grains, and minimally processed proteins. However, this is one study, and weight management involves many factors including overall calorie intake, physical activity, sleep, and stress. For personalized recommendations, consult with a pediatrician or registered dietitian.

This research is relevant for parents and caregivers of children and teenagers, school nutrition programs, and public health officials developing obesity prevention strategies. It’s particularly important for families concerned about their children’s weight or those with family histories of obesity. The findings may be less directly applicable to very young children (under 3) or to populations with very different food systems than Germany. Anyone with specific health concerns should discuss findings with their healthcare provider.

Changes in weight and body composition typically take weeks to months to become noticeable. If a family reduces ultra-processed food intake, they might expect to see meaningful changes in weight trajectory within 2-3 months, though this varies greatly depending on how much change is made and other lifestyle factors. Long-term benefits would likely accumulate over years, as suggested by this 11-year study.

Want to Apply This Research?

  • Track the percentage of daily calories coming from ultra-processed foods. Users can log meals and the app can categorize foods using the NOVA classification, showing daily/weekly percentages. Goal: gradually reduce from current intake to below 20% of daily calories.
  • Set a specific, measurable goal like ‘Replace one ultra-processed snack with a whole food snack each day’ or ‘Reduce sugary drink consumption by one serving per day.’ Users can log these swaps and track streaks to build momentum.
  • Weekly check-ins on ultra-processed food percentage, monthly weight tracking (if appropriate), and quarterly reviews of eating pattern changes. Include reminders to prepare whole-food alternatives and celebrate progress milestones.

This research shows an association between ultra-processed food consumption and weight gain in children, but does not prove that ultra-processed foods alone cause obesity. Weight is influenced by many factors including genetics, physical activity, overall calorie intake, sleep, stress, and medical conditions. This information is for educational purposes and should not replace professional medical advice. Parents and caregivers should consult with their child’s pediatrician or a registered dietitian for personalized nutrition and weight management guidance. Any significant changes to a child’s diet should be discussed with a healthcare provider, especially for children with existing health conditions.