NOT medical advice
FastBro does NOT provide medical, nutritional, psychological, or psychiatric advice. Nothing in this app — every timer ring, every XP reward, every Lab Note, every badge — is a substitute for a conversation with a qualified clinician who knows you. You use the app at your own risk. If you have a health concern, see your doctor.
Talk to a clinician first if any of the following applies
A fasting protocol that's safe for one person can be dangerous for another. Talk to a clinician before you start any fasting schedule — and especially before extending an existing one — if you fall into any of these categories:
- You are under 18, or over 65, and have not fasted regularly before.
- You are pregnant, breastfeeding, or trying to conceive.
- You have (or have ever had) an eating disorder, including anorexia, bulimia, or binge-eating disorder. Fasting apps can be a trigger.
- You have diabetes (type 1 or type 2), reactive hypoglycaemia, or any condition affecting blood sugar.
- You take prescription medication that requires food (some antidepressants, antibiotics, thyroid medication, blood-pressure medication, etc.).
- You have a history of fainting, seizures, heart conditions, kidney disease, liver disease, or are immunocompromised.
- You are underweight (BMI under 18.5) or recovering from illness, surgery, or an eating disorder.
- You experience dizziness, light-headedness, severe hunger, nausea, or vomiting when skipping meals.
The four fasting protocols built into FastBro
FastBro ships four preset intermittent-fasting schedules plus a 5:2 variant. Below is a non-medical summary of what they are — we are not recommending any of them.
- 16:8 — Fast for 16 hours, eat within an 8-hour window. The "starter" protocol.
- 18:6 — Fast for 18 hours, eat within a 6-hour window.
- 20:4 — Fast for 20 hours, eat within a 4-hour window.
- OMAD — One Meal A Day. Fast for 23 hours, eat within a 1-hour window.
- 5:2 — Eat normally five days per week, complete two 24-hour fasts on the other days.
Stop and seek help if you feel any of these
Stop the fast and contact a clinician or local emergency services if you experience any of the following during or after a fast:
- Severe dizziness, fainting, or near-fainting.
- Chest pain, palpitations, or an irregular heartbeat.
- Confusion, slurred speech, or sudden headache.
- Persistent nausea or vomiting you can't stop.
- Extreme weakness, shakiness, or cold sweats.
- Thoughts of harming yourself or recurring distress around food or your body. If you're struggling, contact the National Eating Disorders Association (Helpline: 1-800-931-2237), Beat (UK Helpline: 0808-801-0677), or your country's local crisis line.
Hydration, electrolytes, and food hygiene
During any fast longer than ~12 hours, drinking water is important and so is paying attention to electrolytes (sodium, potassium, magnesium). If you feel unwell, breaking the fast with a balanced meal — not breaking a 36-hour fast with a pizza — is the safer call. If you have kidney problems, talk to your doctor before adding electrolyte supplements.
No fasting guarantees
We make no medical claims about intermittent fasting. We do not claim that FastBro will cause, contribute to, or prevent any specific outcome — weight change, autophagy activation, longevity, metabolic improvement, mental clarity, or anything else. The Lab Notes inside the app label insights as "CONFIRMED / PROBABLY TRUE / GYM BRO LORE" — those labels are honest and you should treat them as a hint, not a clinical reference.
You stay in charge
You can start, stop, abandon, or shorten any fast at any time. The app does not reward skipping medical care, suppressing warning signs, or pushing past discomfort in pursuit of a higher XP number. If a streak feels more important than how you feel, the streak is wrong.
Contact
Bugs, suggestions, or safety reports: Privacy.appsss@proton.me. If you believe the app is encouraging unhealthy behaviour, please tell us — we will treat it as a P1 bug.