Diet Guide
You eat everything in one single meal per day. Nothing else.
OMAD is the most extreme form of intermittent fasting. You eat one large meal a day and fast for the remaining 23 hours. Water, black coffee, and plain tea are allowed during the fasting period.
The one meal should contain your full daily calorie target. This is usually between 1500 and 2500 calories in a single sitting, depending on your size and goal.
There are no rules about which foods to eat. You just eat them all at once.
Think of it like charging your phone once a day. You plug in, charge fully, and then unplug. The phone runs on that single charge for the next 23 hours. Your body works the same way on OMAD. You fuel up completely in one meal, then your body runs on that fuel and stored body fat for the rest of the day. The long fasting window keeps insulin low and encourages fat burning.
OMAD stands for One Meal A Day. That is the whole acronym, sometimes written O.M.A.D. It describes an eating pattern, not a food list. You get one eating window, usually around an hour, and you fast for the other 23. What you put in that meal is up to you.
People also call it the 23:1 fast, because that is the ratio of fasting hours to eating hours. It sits at the far end of the intermittent fasting scale. 16:8 gives you an eight hour window, 20:4 gives you four, and OMAD gives you roughly one.
One thing worth clearing up: OMAD is not a calorie target and it does not have a magic number attached to it. You still eat your normal daily calories, you just eat them all at once. If you need 2,000 calories a day to lose weight, OMAD means 2,000 calories in one sitting. It does not mean eating a small dinner and calling it a day, and it does not mean starving.
The same number you would eat on any other diet. OMAD changes the timing, not the maths. Work out your maintenance calories, take 300 to 500 off for a deficit, and that is your one meal.
For most adults this lands somewhere between 1,500 and 2,500 calories. Run your own numbers with the calculator rather than guessing, because guessing is how people end up eating 900 calories a day and wondering why they feel terrible by week three.
Here is the practical problem nobody warns you about: 2,000 calories in one sitting is a lot of food if you eat the way this site recommends. A big plate of rice, chicken breast and vegetables is filling by design. Some people physically cannot finish their target, which turns OMAD into an accidental crash diet. If that happens to you, add some calorie dense food to the meal, nuts, oil, or full fat dairy, or accept that OMAD is not the right tool for you.
This is the hardest part of OMAD and the reason most gym-going people drop it. If you weigh 80kg and you are aiming for 1.6g of protein per kg, that is 128g of protein. In one meal. That is roughly 500g of cooked chicken breast, or 400g of chicken plus four eggs, or a large piece of fish with a protein shake alongside.
It is doable, but it takes planning and a decent appetite. Lead with the protein while you are hungriest, before the rice and the sides fill you up. If you are lifting and struggling to get it down, 20:4 with two meals will serve you far better than forcing everything into one.
| Pros | Cons |
|---|---|
| Maximum simplicity, one decision per day | Very high hunger for most of the day |
| Long fasting window maximises fat burning time | One large meal can cause energy crashes |
| No decisions about food until the meal | Not suitable for people with blood sugar issues |
| Can eat a full satisfying meal each day | Hard to hit protein targets in one sitting |
OMAD creates a very long fasting window, which reduces total calorie intake in many people by limiting the time available to eat. A 2019 study found that OMAD produced similar weight loss to a standard diet but was associated with higher hunger levels throughout the day. Some unfavorable changes to blood lipid levels were also noted. It works well for people who tolerate extended fasting, but it is not suitable for everyone and should be approached carefully by beginners.
Read the researchThousands of people doing this diet share their experience on Reddit. Visit r/omad
One Meal A Day. You eat everything in a single meal and fast for the remaining 23 hours or so. It is the most extreme common form of intermittent fasting.
Your normal daily target, eaten in one sitting. For most adults that is 1,500 to 2,500 calories depending on size and goal. OMAD changes when you eat, not how much.
The same as any other approach, around 1.6g per kg of bodyweight. For an 80kg person that is about 128g in one meal, which is roughly 500g of cooked chicken breast. Getting it down in one sitting is the main reason people quit.
Yes, black coffee, plain tea and water are fine during the fast. Milk, sugar and condensed milk are not, so kopi peng and teh tarik break the fast.
Not inherently. Both work by reducing total calories. 16:8 is far easier to stick with, and the diet you can sustain always beats the one you quit. Try intermittent fasting first.
Not if you hit your protein and keep lifting. Muscle loss comes from too little protein and no resistance training, not from meal timing. The risk with OMAD is that hitting protein in one meal is genuinely hard.
OMAD is just one way to hit a deficit. Here is calorie counting, the method underneath it, and how I went from 128kg to 86kg without it.
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