Insights from TOMI Study: A Case Study in Toddler Nutrition

Insights from the ToMI Study: Early dietary protein and its role in obesity prevention 

Natàlia Ferré Pallàs¹, Joaquín Escribano Subias^1,2, Esther Parada Ricart^1,3, Verónica Luque¹, Veit Grote^4,5, Hans Demmelmair^4,5 and Berthold koletzko^4,5  

¹ Pediatric Nutrition and Development Research Unit, Universitat Rovira i Virgili, Institut d’Investigació Sanitària Pere Virgili 

² Hospital Universitari Salut Sant Joan de Reus 

³ Hospital Universitari de Tarragona Joan 23 

⁴ LMU University Hospital, Div. Metabolism and Nutrition, Dept. of Pediatrics, Dr. von Hauner Children’s Hospital, Munich, Germany 

⁵ German Center for Child and Adolescent Health, site Munich, Germany 

Early childhood is a critical period for growth and metabolic programming, with long-term implications for health. Rapid weight gain in infancy and toddlerhood is a well-established predictor of later obesity and metabolic disorders. Observational studies and clinical trials have shown that excessive protein intake in early life—particularly from animal sources—can accelerate growth and increase fat mass accumulation. This phenomenon is explained by the “early protein hypothesis,” which suggests that high protein intake stimulates insulin and insulin-like growth factor 1 (IGF-1), promoting fat acumulation [1]. In this context, the Toddler Milk Intervention (ToMI) study was designed to explore whether modifying milk protein intake during the second year of life can influence growth patterns and reduce the risk of latter childhood obesity.  

Previously, the CHOP (Childhood Obesity Project) trial demonstrated that reducing protein content in infant formula during the first year of life significantly reduced BMI and obesity prevalence at school age [2]. However, although the accelerated rate of growth extends into the second year of life—making this period especially sensitive to nutritional influences—the impact of protein intake beyond the first year of life remains unclear [3]. The ToMI study was developed to address this gap by focusing on milk protein intake during the second year of life.  

Study Design and Methodology 

The ToMI trial is a randomized, double-blind study conducted in Germany and Spain with 1,618 children aged 11.5–13.5 months at recruitment. Participants received either lower protein (similar to human milk) or higher protein (similar to cows’ milk) toddler milk formula for one year. Both formulas were isocaloric and nutritionally matched, with adjusted fat content to ensure equal energy density [4]. 

The primary outcome is BMI-for-age z-score at 24 months. Secondary outcomes include BMI at 6 years, obesity prevalence, body composition, metabolic markers, and developmental measures. The study also explores diet, physical activity, and potential epigenetic effects. The first results suggest that children randomized to the lower protein group have a reduced BMI at 18 months compared to those in the higher protein group; althougs this differences was not observed at 24 months [5]. Children consuming the high-protein formula exhibit accelerated weight and length gain, deviating from WHO growth standards, while those in the low-protein group maintain relatively stable z-scores for length and weight from 12 to 24 months of age and growth patterns closer to normative trajectories [5]. 

Scientific and Public Health Implications 

The ToMI study addresses concerns about excessive protein intake in early childhood in well-resourced settings. In Europe, many toddlers consume significantly more protein than recommended, with dairy products contributing as much as half of their total intake [6]. By focusing specifically on milk protein, the study tests a practical intervention with potential for public health application. 

Previous research suggests that reducing protein intake supports healthier growth and lowers the risk of excessive weight gain. If ToMI confirms these findings, it could help to improve toddler feeding guidelines. 

Conclusion 

The ToMI study helps clarify how milk protein intake in the second year of life may affect growth and obesity risk. Thanks to its robust design and long-term follow-up, the study is expected to generate valuable evidence for assessing early nutrition strategies that may guide could inform future feeding practices, support obesity prevention and promote lifelong health.  

References