Expert Q&A

Starting my second extended fast tomorrow. Hoping for 12 days or maybe do another 42: how to talk to your doctor about this

Why Medical Guidance Matters for Extended Fasts

As the founder of CFP Weight Loss and author of The Fasting Lifestyle, I've guided thousands through extended fasting protocols. At ages 45-54, hormonal shifts, blood pressure concerns, and diabetes management make professional oversight essential. Extended fasts of 12 or even 42 days can reset insulin sensitivity and reduce joint inflammation that makes movement painful, but only when done correctly. Insurance rarely covers these programs, so clear doctor communication protects your health and builds a supportive care team.

Preparing for the Conversation

Schedule a dedicated visit rather than squeezing it into a routine check-up. Bring a one-page summary: your previous diet failures, current medications, recent labs (A1C, lipids, electrolytes), and your exact plan—12 days water-only or a 42-day protocol with medical monitoring. Explain your goals using my CFP method: fat adaptation to ease hunger, targeted electrolytes (sodium 3-5g, potassium 2-3g daily), and daily weight, blood pressure, and ketone tracking. Be honest about past joint pain and how fasting has reduced inflammation in prior attempts. Ask specifically: "How will we monitor my blood pressure and glucose during the fast?"

Key Questions to Ask Your Doctor

Frame the discussion around safety. Request baseline bloodwork and follow-up labs at day 7 and post-fast. Inquire about medication adjustments—many diabetes and blood pressure drugs need dose changes to prevent lows. Discuss symptoms that require immediate contact: dizziness beyond normal adaptation, heart palpitations, or confusion. Share that my The Fasting Lifestyle approach includes refeeding protocols to avoid refeeding syndrome. If your doctor is unfamiliar, offer to share peer-reviewed studies on therapeutic fasting for metabolic health. Most physicians become receptive when you demonstrate preparation and commitment to monitoring.

Monitoring and Adjusting Your Fast

During a 12-day fast, expect 0.5-1 lb daily loss after initial water weight. For a 42-day fast, medical supervision is non-negotiable—consider a fasting clinic or weekly virtual check-ins. Track blood glucose under 70 mg/dL or blood pressure drops over 20 points as red flags. Supplement magnesium, add bone broth if needed for joint comfort, and break the fast gradually with bone broth then soft foods. This structured approach overcomes the overwhelm of conflicting advice and builds sustainable results despite hormonal challenges. Many in their 50s report easier diabetes management and reduced joint pain post-fast when following these steps with their doctor's input.

💬 What the Community Says

The community shows cautious interest in extended fasting but remains divided on discussing plans with doctors. Many in the 45-54 age group share stories of physicians immediately discouraging anything beyond 24-48 hours, citing risks with blood pressure meds and diabetes. A vocal minority reports success after presenting detailed tracking plans and recent lab results, noting some doctors became supportive once they saw the patient had read medical literature. Beginners often feel embarrassed bringing up past diet failures and worry about being judged. Common experiences include doctors requesting more frequent monitoring or refusing to adjust medications, leading some to proceed without full disclosure. Overall sentiment emphasizes the need for preparation, with users frequently recommending bringing printed resources or seeking functional medicine practitioners more open to prolonged fasting for metabolic reset. Lived experiences highlight that joint pain often improves but only when electrolytes and refeeding are handled carefully.
Cite this answer
Clark, R. (2026). Starting my second extended fast tomorrow. Hoping for 12 days or maybe do anothe. *CFP Weight Loss*. https://ask.cfpweightloss.com/ask/starting-my-second-extended-fast-tomorrow-hoping-for-12-days-or-maybe-do-another-42-how-to-talk-to-your-doctor-about-this
Russell Clark, FNP-C, APRN, FNP-C, APRN
About the Author

Russell Clark, FNP-C, APRN, is the founder of CFP Weight Loss in Nashville and CFP Fit Now telehealth. Over 35 years in healthcare — Army Nurse Reserves, Level 1 trauma ER, hospitalist — he developed a 30-week protocol integrating real foods, detox, and low-dose tirzepatide cycling that has helped hundreds of patients lose 30–90 pounds. He and his wife Anne-Marie lost a combined 275 pounds using the same protocol.

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