Efecto de la restricción calórica en la composición corporal, la estructura muscular y la eficiencia de la cadena respiratoria mitocondrial en el deportista

Abstract

Introduction: It is proposed to work on a model of caloric restriction (CR) or Intermittent Fasting Diet, which we consider a good option to lose weight in certain circumstances and individuals. It is considered CR when the individuals establish intermittent periods of 16-48h fasting or restriction of 30 to 60% of the caloric content, with respect to the habitual intake, which, on the other hand, remains unchanged between these periods. Recent studies in humans show their beneficial effects through cellular and molecular adaptation mechanisms, contributing a positive effect on pathologies of great morbidity such as diabetes, obesity, cardiovascular diseases, cancer and neurological diseases of senescence such as Alzheimer's or Parkinson's. Some of these adaptive effects included generate a low level of baseline inflammatory pattern as evidenced by the low circulating levels of C-reactive protein and tumor necrosis factor, serum levels of triiodothyronine that are at the lower end of the range of normality, and even of a structural nature, such as the presence of a more elastic left ventricle (LV) when it stiffness is evaluated by echo-doppler; which are similar effects to those observed in animals that submitted to CR. All of them can be considered an advantage in relation to stress and overload that can be cause by exercise practice. In a schematic way, the CR model aims to reduce the total calories ingested per week by maintaining a complete and proportionate amount of macronutrients and micronutrients. The two most common ways to achieve the desired caloric deficit (% CR) are to reduce that percentage each day or to establish intermittent fasting days, where the impact of the restriction is more important. Varady (Varady 2011) finds both methods valid when comparing them in relation to their success on weight loss; although, in the second, the fact of alternating a day of restriction with another one of normal diet seems to offer advantages to consider in the athlete; less impact on muscle mass loss, does not activate the mechanisms of energy reserve and an easier adhesion for this diet model. Content of the research: Eighteen healthy and physically active subjects followed a CR pattern (34.3 ± 15.4%) for 6 weeks, during which they maintained their regular physical activity. At the beginning and at the end of the experiment, physiological parameters of energy efficiency, hematological and biochemical parameters, the inflammatory and oxidative pattern were determined. Body composition was determined as well, and muscle biopsies were performed; all aimed at identifying changes induced by caloric restriction. Conclusion: Considering that weight loss is fundamentally from fat mass (predominantly android), that there is a better adaptation to aerobic performance and that there are no changes in the pattern of inflammatory and oxidative stress; we consider the caloric restriction as a good option for weight adjustment in athletes.