The One-Page Fast

Everything I'd tell a friend who asked me how to start, and nothing I couldn't defend. The protocol is below — read the second half too.

Download the printable PDF

Side one — what to do

1. Start at 14:10, not 16:8

Eat inside a ten-hour window. Don't eat for the other fourteen. In practice: push breakfast later or move dinner earlier until there's a fourteen-hour gap between your last bite one day and your first the next. Stop at eight in the evening, eat again at ten in the morning. You're asleep for most of it.

Do that for two weeks before you change anything. If it feels genuinely fine and you want to go further, make the fast sixteen hours and the window eight — that's 16:8. There is no prize for arriving faster.

2. Week one probably feels bad because you're low on salt

Headache, fatigue, irritability, a foggy head, lightheadedness on standing. When insulin falls, your kidneys shed sodium and water follows. You're not broken; you're low on salt. The fix for most people: a quarter to half a teaspoon of ordinary salt in a glass of water when that flat feeling arrives.

3. Hunger is a wave, and you only ever have to ride one

Hunger isn't a fuel gauge dropping toward empty. It arrives at the times you usually eat, builds, crests, and — if you don't feed it — passes on its own, usually within twenty or thirty minutes. The skill isn't enduring hunger for hours; it's getting through one wave. Water helps, so do coffee or plain tea and a short walk.

4. Don't eat less. Eat the same, in less time.

Compressing your window is not permission to under-eat or to skip protein. Eat normally in the hours you eat. And plainly: when researchers ran intermittent fasting head-to-head against ordinary calorie restriction, matched for calories, the weight loss came out about the same. Fasting's real advantage is that it's easier to keep doing. That's not nothing. It's just not magic.

5. That's the whole protocol

Fourteen-ten for two weeks. Salt if you feel bad. Ride one wave. Don't eat less. You could stop reading here and do this for a year.

Side two — before you start, read this too

This is not medical advice. I'm not a doctor, a dietitian, or a researcher. I'm someone who fasted, paid attention, and then went and read the studies. Talk to a qualified healthcare professional before you change how you eat. Fasting changes blood sugar, blood pressure, hydration, electrolytes, and how your body handles medication. Never disregard professional medical advice, or delay seeking it, because of something you read here.

Do not fast, and speak with a doctor first, if any of these apply

• You have type 1 diabetes, or type 2 diabetes managed with insulin or another glucose-lowering medication. The fast lowers your blood sugar and so does the dose; a dose calibrated for a body that eats breakfast can drive you dangerously low in a body that doesn't. Only the person who prescribed it can change it.
• You take blood-pressure medication. Fasting lowers blood pressure on its own; the two together can put you on the floor.
• You are pregnant, trying to become pregnant, or breastfeeding.
• You have any history of an eating disorder or disordered eating — or rules about food tend to take on an outsized place in your thinking.
• You are underweight, or have been told you are.
• You are under 18.
• You have a history of heart, kidney, or liver disease.
• You take any prescription medication, until the doctor who prescribed it has told you how fasting interacts with it.
• You are recovering from surgery, illness, or injury.

If you found yourself on that list, this page is not instructions for you. It's context for a conversation with your doctor, and nothing more.

Stop fasting, eat something, and get medical help — now, not later

If any of these happen while you are fasting: fainting or nearly fainting; chest pain; heart palpitations or a heartbeat that feels irregular or racing; confusion or disorientation; dizziness that persists rather than passing; severe weakness; vomiting; an inability to keep water down.

These are not part of a fast going well. They are not waves to ride out, and they are not tests of resolve. Eat something and call a doctor. There is no prize for continuing.

A note on disordered eating

Fasting is a structure that can hide a disorder inside it. It has rules, a virtue narrative, and a socially acceptable reason to skip a meal — a genuinely dangerous combination for a person predisposed to restriction. Nothing here is about eating less than your body needs. If food, weight, or your body has become something you fight with, please talk to someone. In the United States, the National Eating Disorders Association keeps a directory at nationaleatingdisorders.org, and if you are in crisis, 988 reaches the Suicide and Crisis Lifeline, staffed around the clock. That conversation will do more for you than this page will.

Watch for these, in yourself: fasting has become a rule you can't break even when breaking it would be reasonable; you treat hunger as a virtue and eating as a failure; the restriction keeps escalating; you've begun hiding it; you feel dread rather than ordinary hunger as an eating window approaches. If any of that is you, stop, and talk to someone.

If you want the why — what fasting actually does, and where the science runs out — that's Fasting, Honestly (coming soon). If you're curious why morning hunger disappears when you stop feeding it, that's Starving After Breakfast. Both are linked from the resources page. Neither promises that fasting will fix what's wrong with you. That's rather the point.

© 2026 John M. Carlson. Educational content only, not medical advice. Consult a qualified healthcare professional before changing your diet, exercise, or medication.