OMAD: what eating one meal a day means, and who it isn’t for

OMAD stands for one meal a day. In practice it’s a fast of about 23 hours with an eating window of around one hour, which is why it’s also called 23:1.

It’s the most demanding of the common protocols. It has loyal fans and also many people who tried it and went back to something more sustainable. Here’s how it works and, above all, who it isn’t for.

OMAD compared with other protocols

Protocol	Fast	Window	Typical meals
14:10	14h	10h	3
16:8	16h	8h	2 to 3
18:6	18h	6h	2
20:4	20h	4h	1 to 2
OMAD	23h	1h	1

The gap with 20:4 looks small in hours, but in practice it’s big: with 20:4 there’s still room for a meal and something else; with OMAD your whole day of eating happens on one plate.

Why some people choose it

People who stick with it usually mention practical reasons more than physiological ones:

• Simplicity: one food decision a day.
• Schedule: very busy days when eating several times is hard.
• Social habit: one long, full family dinner as the only meal.

Be careful with articles promising dramatic benefits from reaching 23 hours. Evidence for specific advantages of OMAD over wider windows is limited, and what works for one person may not work for another.

Who OMAD isn’t for

This is the most important section. Don’t try OMAD on your own if you:

• Are pregnant or breastfeeding.
• Are under 18.
• Have diabetes, especially if you use insulin or glucose-lowering medication.
• Take medication that needs to be taken with food.
• Have or have had an eating disorder, or find it hard to have a relaxed relationship with food.
• Do intense training several times a week.
• Have never done intermittent fasting.

In any of these cases, talk to a health professional first.

If you want to try it, take the stairs

Going from eating five times a day to once is a recipe for quitting. If you’ve decided to try it, a reasonable path is:

1. Several weeks comfortable with 16:8.
2. Then 18:6, until it feels normal.
3. Then 20:4.
4. Only then, some days of OMAD, not necessarily every day.

Many people discover along the way that 18:6 or 20:4 already gives them what they wanted, without the difficulty of a single meal.

How an OMAD day is organized

• Pick a fixed time for your meal, whichever fits your life best. For many people it’s dinner.
• Hydrate during the day: water, black coffee, unsweetened tea.
• Make the meal complete: protein, vegetables, quality carbs, fats. One meal has to cover a lot.
• Don’t turn the hour into a race: eat calmly.

If you struggle to get what you need in a single meal, or end up overly full and uncomfortable, that’s a sign OMAD isn’t your protocol, and that’s fine.

Signs to go back to a wider window

• Frequent dizziness, strong headaches or weakness.
• Thinking about food all day.
• Eating out of control in your window.
• Sleeping badly or feeling irritable most of the time.

Going back to 16:8 isn’t a step backward. It’s choosing the schedule you can keep.

OMAD in Fastii

In Fastii, OMAD is one of the protocols you can choose at setup or switch to anytime. The clock marks 4, 8, 12, 16, 18 and 20 hours on the way to your goal, and you can end early whenever you need to. A 20-hour fast still goes in your history.

The short version

• OMAD is a fast of about 23 hours with a single meal.
• It’s the most demanding common protocol and not a good starting point.
• There are many cases where you shouldn’t do it, or should ask first.
• If you want to try it, work up from 16:8.

General information. Not a substitute for advice from a health professional.