OMAD: One Meal a Day, Done Properly

One meal a day is the easiest fasting protocol to explain and the one most likely to go quietly wrong. Not because the fasting window is too long — twenty-three hours is well tolerated once adapted — but because of what has to happen in the hour that is left.

The arithmetic nobody does

A day's protein for an adult of average size is somewhere between 100 and 140 grams. That is a large steak plus four eggs plus a tin of fish, eaten in one sitting, and most people running OMAD are not eating anything like it. They eat a normal dinner and call it a day's food.

The result is a slow protein deficit that does not announce itself. Muscle is lost along with fat, the scale rewards it, and the composition change only becomes obvious months later. This is the characteristic failure of long-term OMAD, and it is entirely avoidable by deliberately building the meal rather than eating whatever was going to be dinner anyway.

If your one meal looks like everyone else's evening meal, you are not doing OMAD. You are undereating with extra steps.

Building the meal

• Protein first and by weight, not by eye. Aim for the full daily target in the one sitting
• Fat generously — it is where the energy comes from and it slows the meal enough to finish it
• Volume from vegetables for potassium, magnesium and fibre, all of which are otherwise short on this pattern
• Organ meat or oily fish once or twice a week covers most of the micronutrients a single-meal pattern tends to miss
• Eat it earlier rather than later where possible; a very large meal shortly before bed disrupts sleep in most people

Who it suits, and who it does not

OMAD works well for people who find partial restriction harder than total restriction — for whom one decision is easier than three. It suits fat-adapted people, it simplifies travel and work schedules enormously, and the appetite suppression at that fasting length is genuine rather than willed.

It suits poorly anyone trying to build muscle, where the protein distribution matters and a single bolus is inferior. It suits poorly women with a history of menstrual irregularity, where sustained daily long fasts more often disrupt than help. And it is a poor idea for anyone with a history of restrictive eating, because it normalises a pattern that is difficult to distinguish from the disorder.

Signs it has stopped serving you

• Strength dropping in the gym while weight also drops
• Hair thinning, cold hands, or a resting pulse noticeably lower than it used to be
• Sleep worsening rather than improving after the first month
• Thinking about the meal for most of the day, which is a different problem entirely

Any of those is a reason to open the window to two meals rather than push harder. The pattern is a tool, and the measure of a tool is whether it is still working.