One Meal A Day: Advantages and Disadvantages You Must Know | KetoVale
one meal a day

OMAD Diet Plan: What Are The Health Benefits and Possible Risks?

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The One Meal A Day (OMAD) plan is a way to structure one’s meals throughout the day, and also one of the ways to do intermittent fasting – you get all of your calories for the day in a single meal, and fast the rest of the day.

This means that you are essentially following a 23:1 fasting protocol, whereas you fast for 23 hours and eat for one hour.

OMAD can successfully be combined with the keto diet, and that’s exactly what many people do.

We have previously covered intermittent fasting and keto, which is a very successful weight loss strategy, so make sure to check out our article on the topic.

What Do You Eat on OMAD?

Basically, you combine whatever you would eat in a day in a single meal. In other words, you try to hit your macros in one sitting.

Most people who do OMAD skip breakfast and lunch, and enjoy a big dinner. It’s the epic meal time!



This is often the easiest way to do it because it allows you to have dinner with your family, while breakfast and lunch are easier to skip without much hassle (and without too much social pressure, as well).

Based on your lifestyle and on how you feel, you might wish to experiment with different strategies, such as having a big lunch or breakfast and skipping the other meals. Similarly to other types of intermittent fasting, OMAD is a rather flexible approach that allows for modifications, according to each person’s life and preferences.

Before we discuss OMAD in detail, a word of caution is necessary – this is an advanced fasting strategy and might not work for everyone.

We recommend experimenting with OMAD once you have gotten significant experience with other fasting protocols, such as 16:8 or 20:4, and not jumping straight into it. It’s best to give your body enough time to adapt by easing your way into it.

Additionally, the ladies might want to check our article on women and fasting – more aggressive fasting protocols, such as OMAD, might not be advisable for everyone.

Female hormones are very delicate and are greatly influenced by food intake, as well as by food timing.

Longer fasting periods might not be the best strategy for all (or most) women, so if you notice any side effects, be sure to re-evaluate your approach. If this happens, you can consider fasting for shorter periods of time, or alternating between fasting and non-fasting days, and see what works for you best.

We advise you to start with fasting (and especially with OMAD, if you decide to do it) once you are fat-adapted.

It will be much easier to go without food for long hours if your blood sugar is stable and if your body is efficient in burning fat instead of glucose, as it won’t feel so deprived. With fat adaptation, feelings of hunger are much more manageable and take much longer to fully develop.

Advantages of OMAD

OMAD has some definite benefits and advantages, which is also why it’s getting more and more popular. Below you can find the most important of them.

#1. Weight Loss

OMAD can be an excellent weight loss strategy, as it naturally helps you limit the amount of food (and therefore calories) you are eating.

For many people, it feels easier to eat less times per day, but to make each meal large and satisfying – for example, if someone needs to eat 1500 calories in order to lose weight, splitting these into 4 smaller meals feels very different from having one or two big meals that will keep you full for many hours.

If you decide to do OMAD, you might notice that it’s actually quite challenging to fit all your calories within a single meal, and for that reason, you might naturally limit your calories, without any conscious effort.

This is one of the reasons why OMAD works so well for some people when their goal is weight loss – they just cannot eat as much on this meal plan as to go above their calorie allowance.

When doing OMAD, you might notice that you don’t need to consciously restrict yourself so much – being able to eat to satiety and still losing weight is a huge plus for many.

If you are doing keto and OMAD at the same time, you still have to follow your macros and make sure that you are not eating an excessive amount of carbs or that your protein isn’t too low.

Fat, as usual, should serve as a lever which helps you feel full and satisfied. Remember, carbs are a limit, protein is a goal, and fat is a lever.

Related: Weight Loss on Keto: How Much, How Fast and What to Expect

#2. Simplicity

Another advantage of OMAD is that it’s extremely simple to follow – you just have one meal per day and skip the rest.

It makes food preparation easier and faster, as you have to cook and serve a single meal instead of two or three (or more). Of course, you can take this one step further and do meal prep, where you cook a few meals at once and just split them into portions.

Simplicity is a huge advantage when you are dieting, as it will alleviate some of the mental fatigue that can accompany restricting yourself, and will make choices easier to make and to stick to.

The OMAD plan is so simple that you don’t need to worry about making mistakes – you just eat one meal a day, and that’s it.

#3. Convenience

We all know that, when eating out, keto food is not always available, and that sometimes the only options you have are less than ideal.

OMAD can make your life much easier in such cases – if lunch at work means always struggling to find something that’s keto-compliant, how about just skipping lunch and enjoying a huge homemade dinner?

The same goes for traveling – if you have a long-haul flight and want to avoid the (usually horrible) food that they’ll offer during the flight and that you can buy at airports. With OMAD, it’ll feel very easy to just skip these and eat a big, hearty meal when you get the chance to.

#4. Autophagy

One of the main benefits of fasting is autophagy, which is the process in which your body recycles old and defect cells and tissues to make room for new ones.

Autophagy is dependent on many factors, among which low insulin levels is one of the most important ones, and the longer you fast, the lower your insulin is.

This is why the best results in terms of autophagy come with longer fasts, such as 18-24 hours, and OMAD is an excellent strategy for that.

Additionally, OMAD might help with stabilizing blood sugar levels, especially in people with Type 2 Diabetes.

Related: What Breaks a Fast While Doing Intermittent Fasting

Disadvantages of OMAD

While for some people OMAD is an excellent strategy to help with weight loss and simplify food preparation, it might not be ideal for everyone.

#1. Some people might not tolerate it well.

Some people do very well with fasting, while others struggle with it and cannot seem to do it without a substantial effort.

If you feel weak, sluggish and extremely hungry while fasting, this might be your body’s way of telling you it doesn’t agree with going 23 hours without food.

If you decide to give OMAD a try, make sure you let yourself adapt to it over a longer period of time, especially if you haven’t done fasting before. You should slowly introduce fasting in your life by experimenting with shorter fasting periods first, such as 14, 16 and 20 hours.

Additionally, if you have been a grazer your whole life, OMAD might just not be the solution for you – if you want to experiment with having better control over your food choices, it might be well worth considering. However, if it doesn’t feel natural for your body and mind, but like an incredibly difficult mental challenge, it might create too much tension and make it more difficult to stick to good choices altogether.

OMAD might also provoke episodes of binge eating in those who are susceptible to them and should be avoided if you have a history of disordered eating.

#2. It might be difficult to switch back to another way of eating and feel satisfied with smaller portions.

If you do OMAD for long enough, you will find that your body will adapt to big portions and huge meals, and will actually demand these each time you’re eating.

If you decide to switch back to having 2 or 3 meals a day, you might find it challenging at first to feel satisfied with smaller portions, and you might need to retrain your body to feel satisfied with less. This is certainly not impossible but might take some time.

#3. It might be challenging to eat sufficiently.

If you do OMAD, you might unintentionally eat too little. While that’s okay if it happens once or twice, you still need to make sure you’re getting enough protein in, in order not to lose muscle mass, and enough fat, which is necessary for the basic functions of your body.

Fat is usually less of a problem when doing keto, but protein should not be overlooked, and especially not in the long run. You need to eat enough protein and calories for your goals to avoid complications, such as hair loss or losing muscles.

It’s true that the less food you’re eating, the more weight you might be able to lose. However, if you’re systematically under-eating and lose too much weight at once, your body will fight back, and will do so ferociously.

Sustainable weight loss is gradual and takes time; if it’s too rapid, you risk losing muscle mass, and you might quickly bounce back to your previous weight once you stop dieting.

#4. It Might Provoke Some Side Effects (Especially if you’re not Fat-Adapted)

As mentioned earlier, it’s best to do OMAD once you’re already fat-adapted, such as at least 3-4 weeks after starting keto. Being in ketosis all the time is already a huge change for your body – let it adapt to it before introducing another major change to your diet and eating patterns.

Even if you’re fat-adapted, you might still experience some side effects from OMAD, although they’re usually much milder than what you’d experience if you were relying on carbs for energy. 

Common side effects include:

  • Feeling weak and tired
  • Having problems with concentration 
  • Feeling shaky and jittery
  • Headaches

Some of those might simply be a symptom of insufficient electrolytes – it’s a good idea to add some salt to the water you’re drinking while fasting, add a daily magnesium supplement, and to also be mindful of your potassium intake from food (most tracking apps will allow you to also track potassium). 

Some of those might also mean that you’re not fat-adapted yet, or that you need to ease your way into fasting. 

In general, with fasting as with food in general, you should listen to your body. Don’t force yourself to fast for long hours, if it feels unnatural and uncomfortable – physically or mentally. There are plenty of ways to achieve good results. 

On days where you haven’t had enough sleep, or if you’re jet lagged, for example, fasting might be more challenging. However, you don’t need to do it every day – fit it to your schedule, instead of fitting your schedule to it.  

Additionally, if you have any existing health conditions, such as diabetes or problems with your thyroid, fasting might pose an unnecessary risk. Being susceptible to binge eating is another major contraindication to fasting – if that’s your case, do not do it.

#5. It May Cause Issues With Blood Sugar.

The keto diet is an excellent way to sustain blood sugar levels. However, if you’re just starting out, you may not have had the chance to benefit from blood sugar regulation. 

If your body is not used to burning fat as fuel yet, you may experience drops in blood sugar when you go too long without food. This can make you feel dizzy, nauseous, fatigued, and disoriented. 

Be sure you are well into your keto diet and do not have blood sugar issues before starting the OMAD.

Frequently Asked Questions

How many calories are in OMAD?

Basically you will eat all the calories that you would normally consume for the day in one single sitting. Therefore, it’s important to structure your meal so that you get enough micronutrients and macronutrients.

Does OMAD work for weight loss?

Yes, you can lose weight eating one meal a day. According to this study from The American Journal of Clinical Nutrition, eating 1 meal/day leads to weight loss and a decrease in body fat mass compared to eating 3 meals/day. However, you should consult with your doctor and dietitian before starting any weight loss plan.

Can you eat whatever you want on OMAD?

No. OMAD is not some magical program. For optimal results, you always need to make sure you eat healthy and unprocessed foods as well as getting enough vitamins, minerals, and other nutrients from your diet.

Is OMAD diet dangerous?

As we mentioned earlier, there are some side effects and possible risks that might come with eating this way. We need to have more studies on the long-term effects of eating 1 meal/d. Again, you need to talk to your doctor before changing your diet and lifestyle.

Our Conclusion

OMAD can be an excellent solution for some people and might help with weight loss, increase autophagy, and improve your blood sugar levels. However, it’s a rather aggressive strategy that might not be suitable for everyone – if you’re experiencing any significant side effects, it might just not work for you.

As with fasting in general, the OMAD diet plan is very flexible, so you might want to try out different approaches, such as eating a big lunch instead of dinner, or doing OMAD every other day, or a few times a week. The best is just to try and see what works and what doesn’t, and pay special attention to what your body is telling you.

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