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OMAD Diet: What is it and how does it work?

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OMAD is a new invention among the weight loss community. It stands for One Meal A Day and as the name suggests, you only get to eat 1 meal each day. OMAD diet is a more extreme approach to intermittent fasting, usually intermittent fasting is performed using 16:8 ratio where you eat for 8 hours a day and fast for 16 hours whereas OMAD is equivalent to 23:1 where you eat for 1 hour and fast for 23 hours.

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In this post you will find out the benefits of OMAD, dangers and some tips on how to do it correctly. If you are looking for other trendy weight loss diets, check out the Sirtfood diet. This is a diet that helped Adele, a popular singer, to lose a lot of weight.

What is OMAD and how does it work?

OMAD is a diet that enables you to eat only 1 meal per day. Dana Angelo White, a sports dietitian, states that you should eat your 1 meal at the same time each day so you follow a consistent schedule. This will help you to create a routine and your body may adjust better making it realise feeding hours so it stops severe hunger during periods of not eating.

During the time of not eating, you can drink whatever you like as long as these choices are calorie-free. You can drink black coffee or water but ensure you are not adding any milk or sugar to the coffee as this adds calories. OMAD diet does not specify what you should be eating for your 1 meal a day, so you can make the most of it. However, make sure to use a normal dinner plate not an enlarged one and try not to pile on heaps of food as this will cause the diet to be unsuccessful.

OMAD works by limiting the amount of time you can spend eating in a day. Due to the time restrictions, you are unlikely to eat more calories than what your body needs to maintain your weight or gain any weight. As a result, you are likely to be in a calorie deficit which is the most important factor in weight loss. Calorie deficit is what drives weight loss, and it can either be achieved through dieting or exercise.

Some people have reported the diet not working for them, this will be due to them eating enough calories for that 1 meal a day to maintain their current weight or even cause weight gain. If you’d like to ensure successful weight loss, it may be worth calculating how many calories your body needs to maintain its weight and how many calories it requires to lose weight. We’ve got a wee guide here for you. Once you know your daily calorie allowance and sticking to it then you are guaranteed to be successful.

Health Benefits of OMAD

mussell soup

OMAD diet provides the same health benefits to any other intermittent fasting diet.

Weight loss and fat loss

Some scientific studies have proven successful weight loss. For instance, one study compared weight loss between two groups. One group of people fasted using 5:2 method and the other group simply ate in a caloric deficit. The study found that both groups lost approximately the same amount of weight. So, what can we take from this? Intermittent Fasting may help with weight loss, but it is not a superior method to any other diets.

Effects on your metabolism

Effects of intermittent fasting on metabolism are a little more complex and include a few different variables. For example, how fast is your metabolism at the moment? How many days are you planning on fasting? Do you have any medical conditions or take any medications that may affect weight loss?

All these things need to be taken into account. It is easy to assume that everybody will respond similarly to fasting but this is certainly not the case.

Anyway, there is a study by Mansell et al (1990) which looks at the effects of fasting on metabolism. The study reported that your resting metabolic rate increased by approximately 3.6%. This means that when you were sleeping or just relaxing, your body would be burning more calories than it would normally.

May reduce the risk of type two diabetes

One of the driving factors of type 2 diabetes is insulin resistance. Insulin resistance is the name given to cells in our body which do not respond well to a hormone called insulin. This hormone is normally released in response to carbohydrates and sugary foods consumption because it helps to lower blood sugar levels by pushing the sugars into body tissues like muscles.

May relieve stress

A study found that fasting reduces oxidative stress levels (Johnson et al, 2007). Oxidative stress levels occur when there is an imbalance between free radicals (inhaled toxins) and antioxidants in our body. This leads to stress as our body struggles to fight and detoxify our body from those free radicals.

Reduces Inflammation

A study done by Johnson et al (2007) found that fasting improved resistance to oxidative stress as well as reduced inflammation. The participants had asthma, and this study showed that fasting may help reduce the symptoms.

Supports a healthy heart

As you may know, one of the biggest driver of heart disease is bad cholesterol. Well, there was a study looked into the effects of fasting on cholesterol and blood pressure. In this study, bad cholesterol decreased and good cholesterol remained unchanged. In addition, systolic (high) blood pressure reduced.

May reduce the risk of cancer

There was a study done by Lee et al (2012) that examined the effects of fasting on different tumour cells. It was found that fasting may be as effective or even replace some of the chemotherapy drugs. Other studies show similar results. Therefore, although more studies are required on humans since most have been conducted in a tube or on rats, the results are promising.

Fasting may support and protect your brain

Some studies have shown significant improvements to brain health. One study done by Lee et al (2000) found that fasting enabled and encouraged formation of new brain cells. A different study found that fasting may even help with Alzheimer’s disease. For instance, Duan et al (2003) found that fasting reduced progression of Alzheimer’s disease. Other studies also show similar results. However, more studies may be useful because most were done on mice instead of people, so the results may vary.

May increase lifespan

A study conducted by Goodrick et al (1982) found that growth duration in rates was slower by 75% and the lifespan increased by 83%.  In addition, another study done by Sogawa (2000) found that lifespan increased significantly in female mice. This shows that fasting may help you live longer.

If you’d like to find out more information on the benefits of intermittent fasting then you can do so in this post.

Dangers and precautions of OMAD

egg and salmon on toast

OMAD is a very restrictive diet making it very difficult to adhere to. It is simply unsustainable for lengthy periods of time. Also, the diet will not work unless you remain within a calorie deficit but if you starved yourself all day you are likely to feel the need to eat a pizza or something by the time it gets to your meal time. If you do that then there is simply no point in trying this diet.

If you are looking to try the intermittent fasting then you can try with an easier ratio of 16:8 or 5:2  which are explained here.

– May work better with your lifestyle
– Weight Loss
– You may feel better
– Plenty of health benefits
– Feeling of accomplishment
– Not sustainable
– Difficult to adhere to
– Not superior to any other diet
– May lead to binge eating
– May suppress your metabolism if you over do it.

Most commonly asked questions

How much weight will I use on OMAD?

It is impossible to determine how much weight you will lose using OMAD, every body is different and responds to dieting differently but you can determine how much weight you will lose by controlling the calorie deficit. If you calculate your maintenance calories and then deduct 500 calories then you will lose 1lb of weight per week, and this is a safe and sustainable weight loss.

Can I exercise during OMAD?

You can exercise but it may be difficult as you may lack energy due to the calorie restriction. You may get better results if you workout after eating but then you may feel hungry after your workout making it harder to adhere to it.

Should I workout in the morning or evening?

Workout whenever you want to, it does not make a difference to your weight loss. However, if you workout within the 23 hour-fast then you may lack energy whereas if you exercise after eating you may feel hungrier after. This is your call but we’d suggest limiting exercise to something light so you keep some energy.

Can I perform OMAD without losing muscle?

OMAD is a very restrictive diet which requires you not to eat for 23 hours, as a result it will be very difficult for you to maintain your muscle mass as muscle requires constant intake of calories and regular intakes of protein to sustain themselves.

Will OMAD get me shredded?

If you currently have a lean physique and use OMAD to lose the body fat then you are likely to come out on the other side with a shredded physique but you are also likely to lose some muscle mass.

Can I still do weight lifting on OMAD?

Weight lifting is a great way to tone up your body and to grow some muscle but due to the calorie restriction OMAD requires to be successful, you are likely to struggle with pushing yourself to the limits due to low energy levels.

Can I drink alcohol on OMAD?

As mentioned previously, unless the drinks are calorie free you should avoid them.

What is the difference between OMAD and Keto?

OMAD and the keto diets are very different. OMAD causes a calorie deficit due to placing time restrictions on when you can eat whereas the keto diet causes weight loss by removing carbohydrates from the diet. This causes a large calorie deficit as removing a whole macronutrient leads to a calorie deficit by default. You can check out more information on a keto diet here. There is also a different version for vegans you can take a look here.


OMAD is a very restrictive diet that allows only 1 meal day with zero calorie drinks. It is unsustainable for lengthy periods of time which means that proper weight loss for those who struggle to adhere to diets may be inadequate. In addition, it is not superior to any other diet as it simply causes a calorie deficit by restricting time that you can eat. A calorie deficit can be achieved by simply reducing calories, such time constraints are simply unnecessary.

If you are interested in performing OMAD, you can take a look at some recipe books that will give you some great ideas on what to eat for your 1 meal. Amazon sells has some amazing choices, like this cookbook written by Noah Jerris that shows you some great main course options. If you require any further support with how to perform the OMAD diet, you can also now purchase beginners guides on Amazon here.

Moreover, if you are looking for some fat loss recipes or exercise tips, you can download our guides by subscribing to our newsletter below.


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