Fasting
For metabolic health
Most of the experts we follow recommend it.
Fasting activates cellular cleanup and can support metabolic health when balanced with nourishment.
Who is behind it
Voices including a molecular biology PhD, a former research biochemist and a registered nutritional therapist.
How strong the research is
Well studied in published research, as well as in practice.
In their words
“You want to cycle in and out of mTOR activation... fasting state is where all cleaning takes place. The fed state is where all healing takes place.”
a nutritional sciences PhD
Fasting increases the release of growth hormone naturally.
Not going more than 12 hours without caloric intake prevents use of stored energy and promotes insulin resistance.
Fasting while sleeping aligns with the body's natural rhythms and can start earlier as darkness takes place faster.
With care
Some of the minds attach conditions. These are worth reading before you begin.
Fasting can be beneficial on paper but may worsen conditions for those with gut issues, nutritional deficiencies, and poor autonomic nervous system regulation.
Fasting decreases T3 which regulates autophagy, so it can cause detrimental effects in people with suboptimal thyroid function.
Intermittent fasting encompasses diverse patterns such as 5:2 fasting or alternate day fasting without necessarily aligning with circadian rhythms.
Where they disagree
Both sides
Against
Fasting deprives the body of anabolic signals from protein for extended periods, which is not ideal for muscle mass gain
a former research biochemistMost of the minds come down in favour, and the dissent is worth knowing.
Talk it through
Entrain shows what the experts teach, so you can make better decisions with your own clinician. It does not diagnose or prescribe. If something is worrying you, start there.
How this reading was made
Every line here comes from a doctor, scientist or coach speaking publicly, and links to the moment they said it. Entrain listens for where independent experts arrive at the same place on their own, and shows where they part ways. Well studied in published research, as well as in practice.
None of the statements here come with a declared commercial interest. Last refreshed 23 September 2026.
The research beneath it
- Meal Timing, Meal Frequency and Metabolic Syndrome.Nutrients, 2022
- A randomized placebo-controlled clinical trial of nicotinamide riboside in obese men: safety, insulin-sensitivity, and lipid-mobilizing effects.The American journal of clinical nutrition, 2018
- Prolonged fasting reduces IGF-1/PKA to promote hematopoietic-stem-cell-based regeneration and reverse immunosuppression.Cell stem cell, 2014
- Circulating human hepcidin-25 concentrations display a diurnal rhythm, increase with prolonged fasting, and are reduced by growth hormone administration.Clinical chemistry, 2012
- Fasting and cancer treatment in humans: A case series report.Aging, 2009
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