Background. The temporal association between modern food habits, the occurrence of fast food, the trend towards convenience products, and the epidemic occurrence of obesity is evident. The causal relation remains less evident.

Material and methods. We re-analyzed body height, body weight, and macronutrient intake of 1028 children (51.3% girls, 48.7% boys) aged 2–18 years who were investigated between 1985 and 2006 as part of the Dortmund Nutritional and Anthropometric Longitudinally Designed (DONALD) Study. We determined the intake of energy, carbohydrates, fat, and protein.

Results. No correlations were found between the standard deviation scores of the BMI (BMISDS) and daily energy intake (r = 0.060, p > 0.1), between BMI-SDS and fat intake (r = 0.031, p > 0.1), and BMI-SDS and carbohydrate intake (r = 0.050, p > 0.1). Yet, we detected a significant positive correlation between BMI-SDS and average daily nutritional protein (all protein: r = 0.143, p < 0.0001, animal protein: r = 0.151, p < 0.0001). The correlation further increased when protein uptake was calculated as a percent of energy uptake (all protein: r = 0.203, p < 0.0001, animal protein: r = 0.163, p < 0.0001). The correlations depended on the age with maxima just before and during the early puberty (boys: r = 0.31, p < 0.0001, girls: r = 0.36, p < 0.0001). It appears that in these age groups up to 13% of the BMI variance can be explained by protein uptake.

Conclusion. The present investigation confirms the hitherto existing evidence of a significant positive correlation between nutritional protein and body mass index.

Keywords: body mass index, appetite control, protein, obesity, glutamate