Fasting: How to Guide

Fasting potentials are the most interesting topics in the Nutritional Era. Fasting consists of the catabolism of lipids, proteins, and carbohydrates to maintain blood glucose levels in a normal range. The action mechanisms of fasting were firstly understood in minor organisms and later in humans. Nutritional interventions of caloric restriction could attenuate age-associated epigenetic alterations and could have a protective effect against cellular alterations, promoting longevity and health span. While most fasting studies point out the weight and fat mass decreases, it is important to define specific guidelines for fasting and non-fasting days to enhance adherence, minimize the dropout rates of the interventions, and maximize body composition improvement. Although the panorama of evidence on fasting and caloric restriction is wide, there is a lack of a safe fasting protocol to guide physicians in its prescription. The main goal is to identify a how to use guide, a major posology of fasting, inserted within a huge dietetic personalized strategy leading to an optimal and healthy nutritional status.

Efectos de un protocolo de ayuno intermitente sobre la composición corporal y perfil lipídico en estudiantes universitarios

El ayuno intermitente es una estrategia nutricional de creciente interés para el control del peso y mejora de la salud metabólica. El objetivo del presente estudio fue evaluar el efecto de un protocolo de ayuno intermitente sobre la composición corporal, perfil lipídico y los biomarcadores de riesgo cardiovascular en estudiantes universitarios. En este estudio experimental participaron 30 sujetos varones y fueron divididos aleatoriamente en dos grupos, 15 sujetos constituían el grupo experimental (GE) (edad: 20,83±0,98 años) y 15 el grupo control (GC) (edad: 23,71±5,55 años). El GE realizó un protocolo de ayuno 16/8, dieciséis horas de ayuno y ocho horas de ingesta calórica sin limitaciones, dos días consecutivos a la semana durante cinco semanas. Se evaluó la composición corporal, la ingesta calórica, el perfil lipídico y los biomarcadores del riesgo cardiovascular al inicio, mitad y final del protocolo. Se observaron descensos significativos en el GE en pliegues cutáneos, perímetro cintura, porcentaje de grasa, perfil lipídico y biomarcadores del riesgo cardiovascular en comparación con GC (p<0,05). Se encontraron incrementos significativos en la ingesta de colesterol y ácidos grasos poliinsaturados en el GE al final del estudio (p<0,05). Se observaron descensos en el colesterol total, triglicéridos, lipoproteínas de baja densidad y biomarcadores del riesgo cardiovascular a lo largo del protocolo en el GE (p<0,05). Un protocolo de ayuno intermitente 16/8, dos días consecutivos por semana, durante cinco semanas, parece efectivo para mejorar parámetros de composición corporal y perfil lipídico, así como para mejorar los biomarcadores relacionados con el riesgo cardiovascular. Intermittent fasting is a nutritional strategy of high interest in weight control and improvement of metabolic health. The objective of this study was to evaluate the effect of an intermittent fasting protocol on body composition, lipid profile and biomarkers of cardiovascular risk in university students. In this experimental study thirty male subjects participated and were randomly divided into two groups; fifteen subjects constituted the experimental group (GE) (age: 20.83 ± 0.98 years) and fifteen the control group (GC) (age: 23.71 ± 5.55 years). The GE performed a fasting protocol 16/8, sixteen hours of fasting and eight hours of caloric intake without limitations, two consecutive days per week for five weeks. Body composition, calorie intake, lipid profile and biomarkers of cardiovascular risk were evaluated at the beginning, middle and at the end of the protocol. Significant decreases were found in GE in skinfolds, waist perimeter, % fat, lipid profile and biomarkers of cardiovascular risk as compared to GC (p <0.05). There were significant increases in the intake of cholesterol and polyunsaturated fatty acids in the GE at the end of the study (p <0.05). There were decreases in total cholesterol, triglycerides, low-density lipoproteins, and biomarkers of cardiovascular risk throughout the study in GE (p<0.05). An intermittent fasting protocol 16/8, two consecutive days per week, for five weeks, seems effective to improve parameters of body composition and lipid profile, as well as to improving biomarkers related to cardiovascular risk