BACKGROUND: Childhood and adolescent obesity has reached epidemic proportions worldwide. The pathogenesis of obesity is complex and multifactorial, in which genetic and environmental contributions seem important. The gut microbiota is increasingly documented to be involved in the dysmetabolism associated with obesity.

METHODS: We conducted a systematic search for literature available before October 2015 in the PubMed and Scopus databases, focusing on the interplay between the gut microbiota, childhood obesity, and metabolism.

RESULTS: The review discusses the potential role of the bacterial component of the human gut microbiota in childhood and adolescent-onset obesity, with a special focus on the factors involved in the early development of the gut bacterial ecosystem, and how modulation of this microbial community might serve as a basis for new therapeutic strategies in combating childhood obesity. A vast number of variables are influencing the gut microbial ecology (e.g., the host genetics, delivery method, diet, age, environment, and the use of pre-, pro-, and antibiotics); but the exact physiological processes behind these relationships need to be clarified.

CONCLUSIONS: Exploring the role of the gut microbiota in the development of childhood obesity may potentially reveal new strategies for obesity prevention and treatment.