Intermittent fasting for beginners
– the evidence

Our intermittent fasting guide is based on scientific evidence, following our policy for evidence-based guides.

It’s written by Dr. Jason Fung, MD, with the latest major update on January 24, 2020. Review and fact-checking by Franziska Spritzler, RD, and further research and fact-checking by Paul Rutkovskis. The guide was medically reviewed by Dr. Bret Scher, MD, on January 24, 2020.1

The guide contains scientific references. You can find these in the notes throughout the text, and click the links to read the peer-reviewed scientific papers. When appropriate we include a grading of the strength of the evidence, with a link to our policy on this. Our evidence-based guides are updated at least once per year to reflect and reference the latest science on the topic.

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Disclaimer: While intermittent fasting has many proven benefits, it’s still controversial. A potential danger regards medications, especially for diabetes, where doses often need to be adapted. Discuss any changes in medication and relevant lifestyle changes with your doctor. Full disclaimer

This guide is written for adults with health issues, including obesity, that could benefit from intermittent fasting.

People who should NOT fast include those who are underweight or have eating disorders like anorexia, women who are pregnant or breastfeeding, and people under the age of 18.

Should you find any inaccuracy in this guide, please email

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  1. It was also medically reviewed previously by Dr. Andreas Eenfeldt, MD, on March 5, 2019.

  2. A full declaration of potential conflicts of interests of individual authors or reviewers can be found on their personal pages, linked from their names.

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