The Effects of Intermittent Fasting Combined with Resistance Training on Lean Body Mass: A Systematic Review of Human Studies.

Regina Belski,Stephen Keenan,Matthew B. Cooke

doi:10.3390/nu12082349

Abstract

Diets utilising intermittent fasting (IF) as a strategic method to manipulate body composition have recently grown in popularity, however, dietary practices involving fasting have also been followed for centuries for religious reasons (i.e., Ramadan). Regardless of the reasons for engaging in IF, the impacts on lean body mass (LBM) may be detrimental. Previous research has demonstrated that resistance training promotes LBM accrual, however, whether this still occurs during IF is unclear. Therefore, the objective of this review is to systematically analyse human studies investigating the effects of variations of IF combined with resistance training on changes in LBM in previously sedentary or trained (non-elite) individuals. Changes in body weight and fat mass, and protocol adherence were assessed as a secondary objective. This review followed the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. MEDLINE, CINAHL, PubMed and SportDiscus databases were searched for articles investigating IF, combined with resistance training that reported measures of body composition. Eight studies met the eligibility criteria. LBM was generally maintained, while one study reported a significant increase in LBM. Body fat mass or percentage was significantly reduced in five of eight studies. Results suggest that IF paired with resistance training generally maintains LBM, and can also promote fat loss. Future research should examine longer-term effects of various forms of IF combined with resistance training compared to traditional forms of energy restriction. Prospero registration CRD42018103867.

Highlights

Non-linear dieting approaches, such as intermittent fasting (IF), have recently gained popularity as a method of manipulating body composition
The maintenance of skeletal muscle mass, is determined by changes in rates of skeletal muscle protein synthesis (MPS) and skeletal muscle protein breakdown (MPB) [7]
A systematic search was conducted using the databases MEDLINE, CINAHL, PubMed and SportDiscus for original research articles published in peer reviewed journals that had investigated the impact of IF combined with resistance training on body composition

Summary

Introduction

Non-linear dieting approaches, such as intermittent fasting (IF), have recently gained popularity as a method of manipulating body composition. Variations of IF include total alternate day fasting (ADF), modified ADF, time-restricted feeding (TRF) and diet breaks, amongst others [1]. Whilst research into how they affect body composition is relatively recent, fasting for religious reasons has been practiced for centuries. The maintenance of skeletal muscle mass (which is a large component of LBM), is determined by changes in rates of skeletal muscle protein synthesis (MPS) and skeletal muscle protein breakdown (MPB) [7]. Both MPS and MPB rates are influenced by energy balance

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