Natural nutrition is essential in the somatic and neuromotor development of the infant. The role of natural nutrition in the prevention of obesity since infancy has been increasing interest among researchers. The infancy is considered critical in obesity formation through the direct relationship between the body mass index from the age of 2 months and that of the pre-school age. A prospective study made on groups and sub- groups has been described, which included children aged 1-23 months, naturally and formula-fed, overweight or obese and for which there were assessed the most commonly used immune markers (leptin, interleukin-6 and ultra-sensitive C-reactive protein). Correlations (mean and median) between subjects’ weight and immune markers values were performed