Chronobiology and Childhood Obesity in a Mediterranean Spanish Population (ONTIME-JR: Obesity, Nutrigenomics, Timing, Mediterranean, Junior)

Childhood obesity has more than doubled in children and tripled in adolescents in the past 30 y. As consequence, increasingly children and adolescents suffer from elevated blood pressure, impaired glucose tolerance, hyperinsulinemia, dyslipidemia. Obesity has a multifactorial etiology since there are potentially numerous contributors to its development and progression. Chronobiology, the science that studies periodic (cyclic) changes in living organisms, has been recently proposed as a new and promising topic to investigate. Alterations of circadian (24 h oscillations) system may contribute to obesity and its complications development such as high blood pressure, insulin resistance, altered fasting lipid profile. Conversely, in a vicious manner, obesity has been regarded as a fault in the circadian system explainable by the association with imbalances and fluctuations of hormones/genes expressions rhythms under the influence of body weight changes.

Thus, the study will examine changes in circadian rhythmicity over a week period. The primary end point will be to evaluate differences between obese/overweight and non-obese children in chronotypes and the responses of these parameters to meal patterns. In particular, non-invasive measures that are well-established determinants of chronotypes will form the core endpoints for the study. Well designed and age-appropriate questionnaires will provide further information in order to study correlations with eating, sleeping and sedentary/active behaviors.