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Keto OMAD – What is one meal a day?

OMAD stands for one meal a day, where you fast for around 23 hours a day and then consume a large meal in a small eating window (around 1 hour). People swear by it as a weight-loss method as well as helping to break plateaus. So let’s take a look at OMAD on a keto diet.

What is OMAD?

Eat one meal a day, that’s it. Really there’s not much to it, there are no rules on what you can eat, you just need to have only one meal a day. Typically, you will fast for 23 hours a day and then have an eating window of 1 hour where you will consume all your daily requirements (calories, fat, protein, etc…).

During the 23 hours fast, you should only be consuming liquids that contain 0 calories. Typically most people stick to just water and black coffee (no sweeteners, milk or anything else).

ground coffee on beans

Although technically you could consume other 0 calorie drinks like diet soda, it’s better to not have anything containing sweeteners as they may affect your blood sugar levels. This can alter the effectiveness of the fast as well as leave you craving food.

OMAD on keto

It’s become popular to combine OMAD with keto, where you basically practice OMAD and still maintain a low carb diet (commonly less than 20g of carbs per day).

A typical day of Keto OMAD could consist of:

  • Morning to late afternoon – Just black coffee and water
  • Dinner – One big meal consisting of your entire daily macros allowance (e.g. 2000 calories, 20g carbs)
  • Evening to next morning – Water and black coffee (perhaps decaff)

Of course your eating window can be at anytime of the day or night. Whatever works for your lifestyle.

A 2,000 calorie meal needs to be quite nutrient-dense as eating that many calories in one sitting can be a lot. Typically, a large serving of fatty meat such as ribeye can help you achieve your required calorie and protein intake.

Benefits of Keto OMAD

save time with keto omad

There a quite a few reported benefits of implementing OMAD, especially on low carb diets such as keto. Let’s take a look at some of the most popular:

Break weight loss stalls/plateaus

You may be eating keto to help lose weight and it’s highly likely that at some time in your journey your weight loss will stall. It happens to pretty much everyone and can be disheartening not seeing the scales move for an extended amount of time.

Luckily, many people who implement OMAD find that it can help kick-start weight loss and breakthrough that stall.

Easy prep and clean up

You only have to make one meal day so you’ll be cooking less and thus there should be less to clean up! This is great for people who either don’t enjoy food prep or are just too busy. That leads nicely on to the next benefit…

More free time

If you’re only eating once a day just think about the time you will save! Less time spent planning, shopping, preparing and eating meals. Claim back some of the day to spend on your hobbies. It’s also great for people who do shift work or have hectic schedules.

Helps to reduce calorie intake

You can only eat so much food in a 60-minute window and if you’re eating a good amount of low carb vegetables then you’ll get full pretty quick.

It can be difficult to exceed your calorie goal but of course, there are exceptions if you choose food that is calorific like nut butters and fatty meats.

Also, as you can only eat once a day you won’t be mindlessly snacking on anything which can quickly add up.

Downsides and concerns about OMAD

OMAD isn’t for everyone, any cycle of food restriction followed by excessive consumption can trigger eating disorders. If you have a history of eating disorders, you should avoid OMAD.

There are other downsides and concerns that you need to be aware of. If any of the following may affect you then you should perhaps reconsider implementing OMAD into your lifestyle. Always consult your GP if you’re making a drastic change to your diet.

Calorie restriction

If you’re trying to lose weight then by eating one meal day you’ll likely naturally reduce your caloric intake as you can only eat so much in one sitting. However, if you’re doing OMAD on a long term daily basis or are trying to maintain/increase your weight, OMAD can be disruptive.

Being at a constant caloric restriction can affect your resting metabolic rate (total number of calories burned while at rest), which can make weight loss difficult to maintain.

Nutrients and macros

Unless you’re careful and plan your meal, it can be difficult to get all your macros and nutrients in one sitting. This is especially true with your protein intake as it helps you feel satiated so it can be difficult to eat your daily requirement in one sitting. So unless you’re eating a lot of meat and eggs you may need to monitor your intake closely. Insufficient protein can lead to muscle mass loss.

Carb intake

Carrying on from monitoring your macros, eating your entire carb intake in one day can spike your blood sugar levels. This is especially true in certain individuals who are insulin resistant.


People who take daily medication more than once a day with food should not practice OMAD. Consult your GP to find out if other medications exist and what can be done.


Working out while fasting can be difficult for some people, especially at the beginning. You could try it and see how you feel, perhaps try changing your intensity at first to get use to it.

GI and bowels

Eating nothing all day and then consuming a large amount of food can upset your stomach and even lead to diarrhoea. Everyone may experience differing levels of gastrointestinal upset and it is not uncommon.

General health and side effects

It’s not uncommon to experience side effects with Keto OMAD. You’ll likely experience periods where you feel hungry and may even have low energy levels. Many report that it goes away after a short time and occurs less as you get used to fasting.

However, if you continue to experience any ongoing issues like feeling tired, dizzy, sick or anything else, then you should stop OMAD. It’s recommended to have a chat with your GP and see if any changes can be made to help alleviate the side effects, that could include upping your carb intake.

OMAD and intermittent fasting

OMAD is really just an extreme variant of intermittent fasting (IF). Intermittent fasting involves cycling between periods of fasting and eating. The difference with IF is that you can fast for as long or short as you like. Typically most people do 16:8, where you fast for 16 hours a day and eat within an 8 hour window.

OMAD approaches and ideas

So you’re interested in keto OMAD, so what’s the best approach?

Daily use of OMAD is not recommended, instead, OMAD is best done between 1-3 times a week on non-consecutive days. The other days you could either eat normally (3 meals a day with snacking) or practice intermittent fasting like 16:8.

Alternatively, you can break out OMAD when you want to break a weight loss plateau or know that your schedule will be hectic.

Sample 7 day week plan

weekly planner

Monday – OMAD, eat one meal within a 1-hour eating window that contains your entire daily calorie and macro allowances. Drink only water or black coffee during the 23-hour fasting window.

Tuesday – Eat normally or practice intermittent fasting (16:8), still observing a keto diet and your macros.

Wednesday – OMAD, similar to Monday

Thursday – Eat normally, similar to Tuesday

Friday – OMAD, similar to Monday

Saturday – Eat normally, similar to Tuesday

Sunday – Eat normally, similar to Tuesday

You can always change the days around but try and leave a days gap between OMAD days. Throughout the whole week, you should still be keeping your carb intake down to remain in ketosis.

Further reading

Check out the links below to find out more about OMAD and decide if you want to give OMAD a try.

Online articles / reviews

Healthline – I Tried Extreme Fasting By Eating Once a Day

Medium – My 4 month Keto diet with Intermittent Fasting (OMAD)

Bulletproof – OMAD: Should you do the one meal a day diet?

OMAD Diet – How to eat one meal a day with Keto (stop-by-step guide)

Reddit – r/omad – Community for people who practice OMAD


One Meal a Day Intermittent Fasting: The Powerful Secret of the OMAD Diet for Extreme Weight Loss – Not keto focused, but still an interesting read.

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