Resources — How Intermittent Fasting Works
Welcome to the resources page for How Intermittent Fasting Works. Everything below is curated to go alongside the guide.
A Reminder Before You Begin
Intermittent fasting is not appropriate for everyone. If you are pregnant, breastfeeding, have a history of an eating disorder, type 1 or insulin-dependent type 2 diabetes, are under 18, are underweight (BMI under 18.5), or are taking medications that require food, please do not start this practice without medical guidance.
If something feels wrong during fasting — persistent fatigue, sleep disruption, mood crashes, cycle changes, or obsessive thoughts about food — listen to your body. The research benefits are not worth your health.
Your Free Worksheet
The companion worksheet to How Intermittent Fasting Works is yours to print and use as long as you need it. It includes a medical clearance check, daily tracker, 30-day on-ramp checklist, eating window planner, weekly metrics, warning signs to watch for, and weekly reflection prompts.
Download the Fasting Worksheet →
Already inside your purchased PDF as a clickable link.
Free Research & Official Resources
National Institutes of Health — PubMed
Free access to peer-reviewed medical research. Search "intermittent fasting" or "time-restricted feeding" for the actual studies behind the claims you see online. pubmed.ncbi.nlm.nih.gov
Examine.com
Independent, evidence-based nutrition research database. Their summaries of the actual fasting research are some of the best on the internet — neither hyped nor dismissive. examine.com
Academy of Nutrition and Dietetics — Find a Dietitian
Searchable directory of registered dietitians (RDs and RDNs). If you want to do fasting safely with personalized guidance, an RD is the right professional. eatright.org/find-a-nutrition-expert
National Eating Disorders Association — Helpline
If you have any history of eating disorder behaviors, or if fasting is starting to feel restrictive in a concerning way, please reach out. Call 1-800-931-2237 or text "NEDA" to 741741
Recommended Books
The Obesity Code — Jason Fung, M.D.
Nephrologist whose work popularized intermittent fasting for metabolic health. Some of his claims are stronger than the evidence supports, but the core argument about insulin and obesity is well-presented. Find it on Bookshop.org
Eat, Stop, Eat — Brad Pilon
The book that introduced 24-hour fasting to a mainstream audience. Pilon is a researcher who actually conducted human fasting studies. More technical than most popular fasting books. Find it on Bookshop.org
The Circadian Code — Satchin Panda, Ph.D.
Salk Institute researcher whose lab conducted the foundational studies on time-restricted eating. The original science, not the marketing. Find it on Bookshop.org
Burn — Herman Pontzer, Ph.D.
A Duke evolutionary biologist who studies metabolism. Important counterweight to oversimplified fasting marketing — the chapter on what actually drives metabolism may surprise you. Find it on Bookshop.org
Note: Book links go to Bookshop.org. These are not affiliate links — we don't earn a commission. Find any of these at your local library for free.
Tools & Apps
Zero
The most popular fasting tracker. Free version is generous. Includes timer, progress tracking, and educational content. zerolongevity.com
LIFE Fasting Tracker
Free fasting tracker built by Dr. Dom D'Agostino's team. Solid alternative to Zero. lifeapps.io
Cronometer
Free nutrition tracker that handles micronutrients better than MyFitnessPal. If you're worried about hitting protein and nutrient targets in a compressed eating window, this is the right tool. cronometer.com
Curated Video Lessons
How Intermittent Fasting Works — Andrew Huberman
Stanford neuroscientist on the full science of eating windows. Watch on YouTube
The Science of Fasting — Dr. Mike (Harvard)
A medical doctor explains the metabolic mechanisms. Watch on YouTube
Intermittent Fasting Mistakes to Avoid — Thomas DeLauer
Common errors that prevent results. Watch on YouTube
Is Intermittent Fasting Right for Women? — Dr. Mindy Pelz
Important nuances for women's hormones and cycles. Watch on YouTube
What Breaks a Fast? — High Intensity Health
Practical answer to the most common fasting question. Watch on YouTube
Continue Your Knowledge Stack
The rest of the Nutrition library and the Fitness library both build on this:
Browse Nutrition → • Browse Fitness →
Fasting interacts with sleep, training, and stress. Each guide in our library is built to extend the others.
This page is a free companion to the How Intermittent Fasting Works PDF. All links above are to free or third-party resources. We do not earn a commission on any link on this page. This guide is education, not medical advice. If you have any of the medical conditions listed in the guide, please consult a doctor before fasting. Last updated May 2026.