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One Meal A Day Diet (OMAD Diet): Scientific Review – Benefits & Disadvantages


‘One meal a day diet’, the name itself explains what this diet is all about. In this diet, individuals who want to lose weight, eat only one meal a day. The concept of OMAD diet is to cut down the calories, but keep the same nutritional content, which is required by the body. Such an intermittent fasting diet has recently gained a lot of popularity and people usually follow this diet 2 times a week, whereas some people even practice it for 2 weeks a month.

How does it Work

  • The theory behind OMAD diet is that, a person can consume only one meal during the entire day
  • During this diet, a person can get his calories, energy and nutrients from one meal rather than the traditional diet, where 3 big meals and 2 to 3 small meals are consumed
  • When you eat every 2 to 3 hours, you supply calories to your body, which are used as a source of fuel. But during intermittent fasting, the continuous supply of calories is stopped, and your body uses other reserve, such as fat for energy. This results in fat burning and weight loss
  • Moreover, in this type of intermittent fasting, out of 24 hours you fast for 23 hours and eat your meal within 1 hour
  • There are no eating restrictions and there is no focus on calorie counting and the presence of macro and micronutrients from the food you eat. However, it is better to avoid eating outside foods and processed foods
  • In some cases, dieters can even consume calorie-free or low-calorie beverages throughout the day, such as water, black coffee, black tea or green tea

Benefits of OMAD Diet

The possible health benefits of OMAD Diet or One Meal A Day Diet are below:

Aids Weight Loss

Intermittent fasting helps in weight loss because the body depends on fat for its proper functioning. Hence it helps in weight loss. Such a fasting plus caloric restriction helps in fat loss and a drop in visceral fat mass too, fat around the waist circumference. (1)

Enhances Longevity

Research-based studies have found that caloric restriction, which means reduction of caloric intake, while maintaining adequate nutrient intake, as seen in OMAD diet, reduces the morbidity of a host of diseases, including heart diseases, kidney diseases, respiratory and neurodegenerative diseases. It was further found that, such a diet has been shown to increase longevity. (2)


It was observed that calorie restriction was beneficial for individuals with borderline diabetes mellitus and insulin resistance. Intermittent fasting with caloric restriction can enhance resistance to the disease. Besides this, it is very well known that weight loss improves insulin sensitivity, reduces insulin resistance and prevents a pre-diabetic from entering into the diabetic phase. (3)

Improves Memory

Restricting calories by 20 to 25% has been shown to improve memory and cognitive functions. It preserves learning and memory function and reduces oxidative stress. Thus, such a diet can protect the brain cells against damage and destruction and keeps neurodegenerative diseases at bay.

Supports Heart Health

Evidence suggests that reduction in weight decreases the incidence and progression of heart diseases. As intermittent fasting with caloric restriction helps in weight loss, it has a positive impact on heart health too. An interesting study found that fasting 1 day per week with a caloric restriction of 20% results in weight reduction and positive changes in coronary heart disease risk parameters. (4)

Having an altered lipid profile increases the risk of having heart diseases. Intermittent fasting combined with caloric restriction helps in reducing total and LDL cholesterol. The proportion of small atherogenic LDL particles also decreases. This further helps in protecting against heart diseases.

Induces Autophagy

Autophagy is a natural process of the body, where the damaged cells of the body are cleared. It is a defense mechanism that protects the body against infections, malignancy and neurodegenerative diseases.

Enhancement of autophagy has been proposed as a possible treatment for diseases of the brain and central nervous system.

Studies have reported that autophagy can be attained by a simple and inexpensive method: short-term food restriction or fasting.

As OMAD diet involves restriction of food and fasting, it may help in inducing autophagy and it can further protect the body against infections and diseases.

An interesting study found that, short-term fasting promotes cellular cleansing, which helps the body in getting rid of damaged cells.

Such cells are of no use to the body and their clearance reduces the unwanted load from the body.

However, chronic starvation may just do the opposite, that is, inhibit autophagy. This can damage the cells, rather than protecting them. (5)

Increases HGH Secretions

Short-term fasting has a beneficial impact on the hormones. Low levels of human growth hormones in adults causes increased body fat, low bone mass and low lean body mass.

Studies have found that short-term fasting such as OMAD diet increases the secretion of HGH. This protects the body against the onset of diseases, helps in fat burning and preserves lean body mass.

Fasting further blocks the action of other hormones that inhibit the action of HGH. Hence, when done correctly, fasting can be beneficial in preventing diseases and disorders. (6, 7)

Lowers Triglyceride Levels

Fasting facilitates weight loss, reduces the level of triglyceride in the blood and protects the heart against damage.

In OMAD diet, if after 23 hours of fasting, a controlled food intake is practiced after breaking the fast, body weight and excess body fat are reduced.

The concentration of cholesterol and triglycerides in the blood are also reduced. All these factors help in reducing the risk of heart diseases in obese individuals, says a study. (8)

Disadvantages of OMAD Diet

Like every coin has two sides, OMAD diet (One Meal A Day Diet) too has some disadvantages and side effects. Let’s have a look at them:

Wrong Food Choices

As there are no restrictions and people following this diet can eat as per their choice, many of them end up making the wrong choices. If after 23 hours of intermittent fasting, one eats high caloric processed foods, he/ she may lose out the legitimate benefits of fasting done right.

Eating Too Much

Binge eating is another common problem of such a diet. After 23 hours of fast, a person may end up eating heaps of high calorie and high fat foods. Thus, if a person fasts for 2 days in a week, he/ she may consume more calorie dense, unhealthy foods than the remaining 5 days.

Long-Term Obesity

During intermittent fasting if a person ends up eating more than the prescribed energy goals, then it may lead to weight gain rather than weight loss. It may also give rise to other health conditions that are associated with weight gain and obesity.

Digestive Pressure

Though eating one meal a day without any restrictions may feel like a feast, it increases pressure on your digestive system to digest huge amount of food altogether. When you eat frequent meals throughout the day, your stomach does not need to work so hard, but in case of OMAD diet, there is an extra pressure on your stomach to digest huge amount of food. This may also result in acidity or heartburn.


OMAD diet may have some short-term health benefits, but in long-term this kind of diet may cause weight gain and health disorders. Besides physical side-effects, OMAD diet may affect your mental health too, like decreased concentration and ability to focus. However, every individual is different and such a diet will have different effects on everyone.

Risks and Dangers of OMAD Diet

  • You may feel tired and lazy
  • Headache and dizziness are common
  • You may not be able to concentrate properly
  • You may feel hungry and restless
  • Irritability and mood swings
  • Some individuals may even experience low blood glucose levels

What to Eat & What Not to Eat

Intermittent fasting is the first important part of OMAD diet, but what goes into your stomach in one hour when you eat your meal is more important and the results depend on what you eat and what you avoid.

  • Vegetables- Consume 4 to 5 servings of fresh vegetables. Do not opt for canned vegetables
  • Fruits- Consume fresh, seasonal, whole fruits. Choose whole fruits over fruit juices. Do not eat canned fruits
  • Whole grains- Whole grains are a good source of dietary fiber. They provide satiety and make you feel full for a longer period of time. Do not eat refined flour and its products like, bread, pasta and noodles. These products hardly contain dietary fiber and nutrients.
  • Protein: Proteins are required for the wear and tear of the body. If you are a vegetarian select pulses, lentils, soy and low fat dairy products to get your dose of healthy protein. 
  • Say No to Processed Foods: If after 23 hours of intermittent fasting, some unnatural and processed food goes into your stomach, it is definitely not worth your effort. Choose foods that are natural, wholesome and full of nutrients.

Final Verdict

  • Talk to a Certified Registered Dietician about a healthy and well-balanced diet plan for weight loss and overall better health
  • Exercise 5 times a week and make sure you eat a healthy, nourishing and a well-balanced diet
  • Choose healthy eating options over processed and unnatural foods
  • Restrictive diets are not fit for everyone. Understand your body and its needs and do not push your body towards something, which it cannot manage
  • Choose the right eating plan and pair it with exercise and healthy food choices

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