Is it okay to do OMAD every day? Understanding the daily risks and benefits

October 18, 2025 •

4 min read

According to a 2022 study, eating a single meal in the evening may lead to greater body fat and total body weight loss than consuming three separate meals with the same caloric intake. The one meal a day (OMAD) diet, an extreme form of intermittent fasting, has gained popularity for this potential benefit, but its daily practice requires careful consideration of both its rewards and significant risks.

Quick Summary

The OMAD diet restricts eating to a single meal per day, a practice linked to potential weight loss and improved insulin sensitivity. However, experts caution against daily, long-term use due to significant risks, including nutrient deficiencies, fatigue, muscle loss, and the potential for disordered eating. Less restrictive intermittent fasting methods are often considered more sustainable and safer.

Key Points

Not Recommended for Long-Term Daily Use: While daily OMAD can lead to quick weight loss, experts generally advise against long-term, daily practice due to significant health risks and unsustainability.
High Risk of Nutrient Deficiency: It is extremely difficult to consume all necessary vitamins, minerals, and protein in a single meal, which can lead to long-term health problems.
Potential for Muscle Loss: Extreme, prolonged fasting can contribute to the loss of lean muscle mass, especially if protein intake is insufficient or mistimed.
Associated with Side Effects: Many experience fatigue, irritability, dizziness, and intense hunger during the prolonged fasting periods.
Consider Less Extreme Alternatives: For sustainable health and weight management, less restrictive intermittent fasting methods like 16:8 are often safer and easier to maintain.
Consult a Doctor Before Starting: Individuals with pre-existing conditions like diabetes or a history of eating disorders, as well as pregnant women, should avoid daily OMAD unless under strict medical supervision.

What Is the OMAD Diet?

The One Meal a Day (OMAD) diet is an intense version of intermittent fasting, involving a 23:1 eating pattern where all daily calories are consumed within a one-hour window. The goal is to induce prolonged fasting, encouraging the body to use stored fat for energy. While some find OMAD appealing for its simplicity and potential for rapid weight loss, its daily practice and long-term health effects are debated by experts.

Potential Benefits of Daily OMAD

While research specifically on daily OMAD is limited, studies on intermittent fasting and some anecdotal reports suggest potential advantages:

Promotes Weight and Fat Loss: The restricted eating window can lead to a calorie deficit. A 2022 study showed that a two-hour eating window in the evening resulted in greater fat and weight loss over 11 days compared to three meals with equal calories.
Enhances Metabolic Flexibility: Extended fasting periods may improve the body's ability to switch between burning glucose and fat for fuel.
Improves Insulin Sensitivity: Intermittent fasting, including OMAD, has been linked to better insulin sensitivity, which can aid in blood sugar control, particularly for managing type 2 diabetes under medical guidance.
Boosts Mental Clarity: Some individuals report improved focus during fasting, possibly due to more stable energy levels.
Encourages Cellular Repair (Autophagy): Extended fasting may stimulate autophagy, a process where the body clears out damaged cells.

The Significant Risks of Daily OMAD

Health professionals are cautious about daily, long-term OMAD, often emphasizing that the risks may outweigh the benefits.

Nutritional Deficiencies

Consuming a day's worth of calories and essential nutrients in one meal is difficult, especially for those with high caloric needs or specific dietary requirements. This can lead to nutritional deficiencies over time, causing fatigue, weakness, irritability, hair loss, and reduced immune function.

Physiological Side Effects

Adapting to a 23-hour fast can cause several adverse effects, including:

Intense hunger and cravings, potentially leading to overeating during the eating window.
Low energy, fatigue, shakiness, and irritability due to fluctuating blood sugar.
Digestive issues like nausea, bloating, and constipation from consuming a large volume of food at once.
Headaches and difficulty concentrating.

Impact on Metabolism and Muscle Mass

Contrary to some beliefs, extreme fasting can slow metabolism and lead to muscle loss. While weight loss occurs, muscle mass may be significantly reduced. Athletes or active individuals may find it especially challenging to consume sufficient protein in one meal to maintain muscle.

Sustainability and Disordered Eating

Daily OMAD is often unsustainable due to its restrictive nature and potential for social disruption. It can also contribute to disordered eating patterns, such as cycles of restriction and bingeing.

Daily OMAD vs. Other Intermittent Fasting Methods

Less restrictive intermittent fasting methods are often considered a better balance for many. Here is a comparison of daily OMAD to the 16:8 method.


Feature	Daily OMAD (23:1)	16:8 Intermittent Fasting
Eating Window	1 hour	8 hours
Fasting Period	23 hours	16 hours
Meal Frequency	One large meal	Two to three meals
Nutritional Balance	Very difficult to achieve daily nutrient needs in one meal, increasing risk of deficiency.	More manageable to meet nutrient requirements across multiple meals.
Sustainability	Low for most people; high dropout rates.	Much higher; easier to integrate into social life and daily routines.
Metabolic Effects	High metabolic stress; potential for increased LDL cholesterol and blood pressure in some.	Less intense metabolic shifts; potential benefits with fewer side effects.
Hunger Management	Intense hunger and cravings are common, especially initially.	Hunger is generally more manageable and decreases over time as the body adapts.
Muscle Maintenance	High risk of muscle loss without careful planning.	Easier to maintain muscle mass with proper protein distribution.

Who Should Not Do Daily OMAD?

Certain individuals should avoid daily OMAD unless under strict medical supervision:

Pregnant or breastfeeding women.
Children and teenagers.
Individuals with a history of eating disorders.
People with diabetes, hypoglycemia, or other blood sugar issues.
Individuals on medications that require food intake.
Highly active individuals and athletes.

How to Approach OMAD Safely

If you are a healthy adult considering OMAD, prioritize safety and a gradual approach.

Start Gradually: Begin with less restrictive methods like 16:8 or 18:6 fasting.
Make It Nutrient-Dense: Your one meal should include lean proteins, healthy fats, complex carbohydrates, and plenty of vegetables.
Stay Hydrated: Drink water, black coffee, or herbal tea during fasting. Electrolytes can also help.
Listen to Your Body: Pay attention to signs of fatigue, dizziness, or irritability, which may indicate OMAD isn't suitable.

Conclusion

Daily OMAD is generally not recommended as a long-term strategy for most people due to significant risks, including nutrient deficiencies, muscle loss, and the potential for disordered eating, outweighing the short-term benefits of weight loss. Less restrictive intermittent fasting methods, such as 16:8, are often considered safer and more sustainable. Always consult a healthcare professional before starting daily OMAD to determine if it is appropriate for your health needs. Focusing on sustainable, healthy lifestyle changes is crucial for long-term well-being. For further information on safe intermittent fasting, refer to Healthline's detailed guide.

Frequently Asked Questions

For most individuals, practicing OMAD every day is not sustainable long-term. Its restrictive nature can lead to intense hunger, social isolation, and an increased risk of nutrient deficiencies, leading many people to eventually abandon the diet.

The biggest risks include developing significant nutritional deficiencies, losing lean muscle mass, experiencing severe fatigue and mood swings, and potentially triggering disordered eating patterns.

Yes, it is possible to lose weight on daily OMAD because you are likely consuming fewer calories overall. However, this weight loss can be accompanied by muscle loss and metabolic slowdown, and less extreme methods of calorie reduction can be equally effective and healthier.

Daily OMAD is not recommended for pregnant or breastfeeding women, children, teenagers, people with diabetes or hypoglycemia, those with a history of eating disorders, and individuals on specific medications that need to be taken with food.

To make your one meal as complete as possible, focus on nutrient-dense, whole foods. Include a balanced mix of lean protein, healthy fats, complex carbohydrates, and a wide variety of vegetables and fruits to maximize vitamin and mineral intake.

Not necessarily. While OMAD is a more extreme form, many health professionals consider less restrictive methods like 16:8 or 18:6 fasting to be safer and more sustainable for long-term metabolic health and weight management, with fewer risks.

The intense hunger caused by prolonged fasting can increase the risk of binge eating during your one meal, leading to digestive issues and potentially consuming more calories than you would otherwise. This defeats the purpose of the diet and can negatively impact health.