Food during the night is a factor leading to obesity

The present review aims to present evidence obtained in clinical surveys and experimental studies that point out the relevance of meal schedules on metabolism and body weight. Recent findings indicate that in spite of ingesting equivalent amounts, food ingestion during the day or during the night can have completely different effects on metabolism determining bodyweight gain and propensity to obesity. Such findings find support in studies of the circadian rhythms, driven by a biological clock located in the anterior hypothalamus, which transmits temporal signals to the body including functions for energy balance. Circadian cycles are normally driven by the alternation of the day- night luminosity cycles, however metabolic changes resulting from food have proven to be powerful temporal signals capable of modifying de temporal order in tissues and cells. Considering the power of food elicited signals, the feeding schedule must coincide with the timing signals driven by the biological clock. Thus eating during the hours normally assigned for sleep and rest leads to a loss of coordination between metabolic rhythms and the biological clock. This circadian disruption occurs at different levels, among cells in a specific tissue as well as in the molecular processes in cells. The aim of this review is to emphasize the adverse effects that meals during the night can exhert on metabolism, we provide evidence about circadian and metabolic alterations at different regulatory levels. Esta revisión tiene como objetivo presentar evidencias obtenidas mediante observaciones clínicas y modelos animales que señalan la relevancia que tiene el horario de alimentación sobre el metabolismo y el mantenimiento del peso corporal. Hallazgos recientes han puesto en evidencia que la misma cantidad de alimento ingerida durante el día o la noche afecta diferencialmente el metabolismo, lo que determina una diferencia significativa en el desarrollo del sobrepeso y la obesidad. Este conocimiento se fundamenta en el estudio del sistema circadiano, regido por el reloj biológico del hipotálamo anterior, que le transmite tiempos a todas las funciones del cuerpo, incluyendo aquellas para el gasto y el ahorro de energía. A pesar de que estos ciclos circadianos están normalmente regulados por los cambios de iluminación resultantes de la alternancia del día y la noche, los cambios metabólicos que resultan de una comida han mostrado también ser señales de tiempo que modifican el orden temporal de a