OMAD fasting: a practical guide to One Meal A Day

What OMAD actually means

OMAD stands for One Meal A Day. In practice it is a 23:1 schedule — roughly 23 hours of fasting followed by a single eating window of about an hour. Some people run a slightly gentler 22:2. Water, plain tea and black coffee are typically taken during the fast; anything with calories ends it.

Compared with 16:8 or 18:6, OMAD compresses all of your food into one sitting. That makes it simple to plan but harder to hit your protein, fibre and micronutrient needs, which is why most people work up to it rather than starting there.

What happens hour by hour

• 0–4 hoursDigestion and absorption of your meal. Blood glucose and insulin are elevated.
• 4–12 hoursGlucose returns to baseline and the body works through stored glycogen.
• 12–18 hoursGlycogen runs low and the body shifts toward using stored fat for fuel.
• 18–23 hoursDeeper fat-burning, with ketone production rising for many people.
• Your eating hourOne meal — protein first, plenty of fluid, and no rush.

Timings are general guidance and vary with your last meal, activity and individual metabolism.

Who OMAD is not for

Skip OMAD, and talk to a healthcare professional first, if you are pregnant or breastfeeding, under 18, diabetic or taking glucose-lowering medication, underweight, or have a history of disordered eating. Anyone on regular medication or managing a medical condition should get individual advice before compressing meals this far.

FastLah is a wellness and habit-tracking app, not a medical device, and does not provide medical advice, diagnosis or treatment.

Making the one meal count

• Lead with protein and vegetables, then carbohydrates — it is hard to catch up on protein in one sitting.
• Keep drinking through the fast. Most people underestimate fluid on OMAD, especially in tropical heat.
• Break the fast gently. A very large, very fast meal after 23 hours often feels worse than a measured one.
• Anchor the window to your life — many people in Singapore, Malaysia and Indonesia find an evening meal with family easiest to sustain.

Tracking OMAD in FastLah

FastLah supports OMAD as a built-in protocol alongside 16:8, 18:6, 20:4 and custom windows.

• A live fasting ring and phase timeline, so you can see exactly where a 23-hour fast has taken you.
• Milestone alerts as you pass each phase, plus hydration reminders through the long stretch.
• Break-fast food logging and a full meal and macro tracker, so one meal still hits your targets.
• Weight trend, mood and energy journalling to see whether OMAD actually suits you.
• An AI Coach you can ask about your own OMAD schedule, and CSV or PDF export to share with your doctor.