Research

Hormonal

Intermittent Fasting (IF) in normal-weight subjects may cause adverse metabolic effects, including increased visceral fat, muscle insulin resistance, and increased intramyocellular triglycerides, which are not seen with Intermittent Energy Restriction (IER) or Continuous Energy Restriction (CER).

If you are already lean, avoid total fasting (0 calories). It may cause your body to store fat in your muscles and liver, worsening insulin sensitivity. Stick to partial restriction (eating some food) if you want to try intermittent fasting.

LimitedRefutesLOW confidence
Periods of IER each week will induce lipolysis and fluxes in FFAs... Single bouts of total fasts (24–48 h) in non-obese subjects have been associated with modest increases in hepatic and intramyocellular triglyceride content... IF regimens reduced energy intake and weight but increased visceral fat, fat cell size and had adverse effects on insulin sensitivity compared to heavier ad libitum fed animals
Michelle Harvie et al. · Behavioral Sciences · 2017

Why this rating

Based on small, short-term studies in non-obese subjects and animal models; clinical significance is uncertain.

Source

Potential Benefits and Harms of Intermittent Energy Restriction and Intermittent Fasting Amongst Obese, Overweight and Normal Weight Subjects—A Narrative Review of Human and Animal Evidence

Michelle Harvie et al. · Behavioral Sciences · 2017

DOI 10.3390/bs7010004

narrative_reviewCited 170×
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DOI resolved against Crossref · corpus check 2026-06-10

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