Impact of intermittent fasting (5:2) on ketone body production in healthy female subjects

Peer-reviewed / Manuscript (Original) received: 11.06.2018 / Revision accepted: 19.07.2018

Introduction

One of the greatest health policy challenges we currently face is the “obesity epidemic”. Obesity is associated with various metabolic complications such as insulin resistance, dyslipidemia, hypertension, type 2 diabetes mellitus, and cardiovascular disease, all of which can be countered through weight loss. Accord- ing to current recommendations, this can be achieved through moderate restriction of daily energy intake [1].

In recent years, there has been increasing dis- cussion around periodic energy restriction in the form of intermittent fasting (IF) as an alternative nutrition strategy for weight man- agement and management of metabolic dysfunctions [2–9]. Intermittent fasting involves a period of fasting that is repeated at regular intervals over the course of a certain amount of time – a day or a week [1].

In the case of time-restricted feeding (TRF), food intake is restricted to a defined time window during the day [10]. Here, the natural break from eating that occurs during sleep at night creates an overnight fasting (OF) period. Extending the OF period achieves the requirements for TRF [11].

Abstract

Intermittent fasting is a growing trend – used for weight loss and for increasing well-being. This nutrition strategy consists of fasting for short periods over the course of a day, or over the course of a whole week. During longer fasting periods, the main ketone body beta-hydroxybutyrate (βHB) plays an important role in energy supply. The 5:2 diet consists of eating normally on 5 days of the week and fasting for 2 non-consecutive days. In this single-arm, non-controlled, interventional study, 19 healthy female subjects followed the 5:2 diet over a 7-day interventional period. 13 of the subjects completed the study. Through the measurement of blood ketone (βHB) levels, it was demonstrated that there was a marked increase in ketone body levels in the blood during the aforementioned fasting period. During the second fasting day, adaptation was already observable. There was a reduction in βHB values and an increase in blood glucose concentration, together with a simultaneous reduction in the occurrence of unfavorable effects such as dizziness, shaking, tachycardia, and nausea.

Keywords: intermittent fasting, ketone bodies, beta-hydroxybutyrate, weight loss, prevention, energy restriction

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