Extended Fasting Clock

For gut-reset (24h), fat-burner (36h), and multi-day metabolic resets. Assisted mode includes bouillon, salt, and electrolytes per Dr. Westman and Dr. Boz.

How to use this

  1. Choose water-only or assisted fasting, pick your goal hours, and set your profile for personalized guidance.
  2. Tap Start fast when you finish your last bite. When you reach your goal, we show how to break the fast with meal ideas.
  3. Follow doctor-sourced tips for electrolytes, cycle timing, and when to break your fast safely.
Fasting type
Goal duration

Optional: Dr. Boz Ratio (glucose ÷ ketones)

Track metabolic progress during your fast. Target under 80 for ketosis; under 40 for deeper benefits (Dr. Boz).

Breaking a prolonged fast (36h+)

Extended fasts require the gentlest refeed. Dr. Westman warns that refeeding syndrome is a serious risk beyond 24 hours — reintroduce food slowly in small amounts.

How to break your fast

  1. 1Step 1 — Hydrate first: plain water or a cup of warm bouillon/bone broth (Dr. Westman) for sodium. Wait 15–30 minutes.
  2. 2Step 2 — First bite: a small portion only — think ¼ of a normal meal. Scrambled eggs, cottage cheese, or a few bites of chicken salad.
  3. 3Step 3 — Wait 30–60 minutes. Notice how you feel. Stop if nauseous or dizzy.
  4. 4Step 4 — Second mini-meal (if hungry): protein + healthy fat + a small amount of low-carb vegetables. Still avoid a large plate.
  5. 5Step 5 — Resume normal low-carb meals over the next 12–24 hours. Do not binge on carbs or sugar.

What to avoid

  • • Large carb-heavy meals (pizza, pasta, bread, sweets) — can spike blood sugar and trigger refeeding complications.
  • • Alcohol for at least 24 hours after a prolonged fast.
  • • High-fiber feasts immediately — add vegetables gradually.
  • • Eating quickly or until stuffed — nausea and cramping are common if you rush.

Expert tips

  • Dr. Mindy Pelz: Break with protein, healthy fat, and fiber — not a carb-heavy reward meal. Your gut needs time to wake up.
  • Dr. Eric Westman: Refeeding syndrome is real on fasts over 24 hours. Start small, go slow, and seek medical help if you feel chest pain, confusion, or severe weakness.
  • Dr. Boz: After a long fast, prioritize protein and fat to keep insulin stable. Avoid breaking ketosis with a sugar load.

Not medical advice. Guidance synthesizes public teachings from Dr. Mindy Pelz, Dr. Eric Westman, and Dr. Boz. Talk to your doctor before fasting — especially on diabetes, blood pressure, or kidney medications.

Fasting timer

Ready to start

00:00:00

Set your goal and tap Start fast. Your timer persists if you close the tab.

Frequently asked questions

How often should I do a 24-hour fast?

Dr. Mindy Pelz suggests once weekly or every other week for metabolic flexibility. Quarterly 24–36 hour fasts can provide deeper cellular clean-out.

What is the Dr. Boz Ratio during a fast?

Divide fasting glucose (mg/dL) by blood ketones (mmol/L). Above 80 = glucose-dominant; 40–80 = moderate ketosis; under 40 = deeper therapeutic ketosis and autophagy-friendly metabolism.

Why use assisted instead of water-only for long fasts?

Dr. Westman and Dr. Boz emphasize sodium and electrolytes during extended fasts. Bouillon, salt water, and magnesium help prevent headaches, cramps, and refeeding complications.

Metabolic Low Carb Calculator · https://metaboliclowcarb.com