Research

Hormonal

Intermittent fasting (IF) is a suboptimal dietary strategy for optimizing muscle protein remodeling and maintaining muscle mass because prolonged fasting periods increase muscle protein breakdown (MPB) and reduce the frequency of muscle protein synthesis (MPS) stimulation, leading to a less favorable net protein balance compared to balanced meal feeding.

If your goal is maximizing muscle size or quality, avoid long fasting windows (e.g., >16 hours) if possible. Spread your protein intake across 3-4 meals every 3-5 hours to keep muscle protein synthesis stimulated. If you practice IF for fat loss, ensure you consume enough total protein (≥1.6 g/kg/day) and consider resistance training to mitigate potential muscle loss.

ModerateRefutesMEDIUM confidence
we propose that infrequent meal feeding and periods of prolonged fasting characteristic of models of intermittent fasting may be counter-productive to optimizing muscle protein turnover and net muscle protein balance.
Eric Williamson et al. · Frontiers in Nutrition · 2021

Why this rating

The paper is a perspective/commentary based on acute metabolic studies and extrapolation; it explicitly states no chronic IF studies measure muscle protein kinetics directly.

Source

A Muscle-Centric Perspective on Intermittent Fasting: A Suboptimal Dietary Strategy for Supporting Muscle Protein Remodeling and Muscle Mass?

Eric Williamson et al. · Frontiers in Nutrition · 2021

DOI 10.3389/fnut.2021.640621

narrative_reviewCited 35×
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DOI resolved against Crossref · corpus check 2026-06-10

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