Consuming all your needed calories for the day in just one meal sounds extreme, but this is what OMAD — which stands for one meal a day — is about.
People on different types of diets, including keto, vegetarian, and Mediterranean, use OMAD fasting for various reasons. One of these is to improve weight loss. But is it right for you? Are its benefits backed by science? How do you follow it safely?
This article explains everything you need to know about OMAD.
What is OMAD?
OMAD, or one meal a day diet, is a form of intermittent fasting that requires you to limit your eating window to 1 hour. For the remaining 23 hours, you eat or drink nothing, except for beverages with zero calories, such as black coffee and unsweetened tea.
Like other intermittent fasting methods, OMAD results in a reduced daily caloric intake, because it’s impossible to eat large amounts of protein, fats, and carbs in one sitting — unless you obtain your calories from highly processed foods, which are bad for your health and waistline.
To do OMAD successfully, it’s recommended to focus on breaking your fast with whole, nutritious foods. Examples are eggs, bone broth, green leafy vegetables, meat, and poultry. No matter what diet you’re on, your foods should be nutrient-rich to avoid deficiencies and related problems.
Later in this guide, we’ll provide you with a sample meal plan to help you get started.
How Does the OMAD Diet Work?
The rules are simple: Eat only one meal a day within 1 hour. Depending on your schedule, this would look like eating only breakfast (from 8:00-9:00 am), lunch (from 11:00 am-12:00 noon), or dinner (from 5:00-6:00 pm). You can set the window whenever you’d like.
Note that OMAD doesn’t involve any calorie or macro goals, which means that you’re not supposed to count anything from your OMAD meal. It also means that anyone can do OMAD regardless of their current diet, although the best use of OMAD is to do it while you’re on a diet that promotes health.
Despite the one rule, which is eating only one meal, OMAD can be extremely challenging for newbies. This includes people who have never tried intermittent fasting before and are eating excessive amounts of carbs each day, especially refined carbs.
Here’s why:
Going without food for 23 hours a day lowers your blood glucose and depletes your glycogen stores. This causes your body to get energy from fat, a process called ketosis (*). If you’ve accidentally skipped a meal, you might recall having experienced tiredness, dizziness, and nausea.
These are signs that your body isn’t used to burning fat for fuel or it isn’t fat-adapted. Fat adaptation is what allows you to go longer without food without experiencing negative symptoms.
Reaching this state takes work, and it entails limiting your carb intake or going on a keto diet. Additionally, instead of jumping right into OMAD, you could try fasting for short durations — such as a 12-hour fast or 16-hour fast — until you feel comfortable fasting for 23 hours.
OMAD Benefits
OMAD can be used as a tool to improve your metabolic health. If you’ve tried shorter fasts before and are ready to do OMAD a few days a week, here are the benefits of one meal a day:
1. Overcome weight loss stalls
Eating one meal a day to lose weight is sometimes recommended by healthcare providers or coaches to individuals who need help breaking through a stall. Hitting a weight loss plateau is frustrating, and intermittent fasting (OMAD as one method) can be a more effective strategy for overcoming it compared to daily calorie restriction.
Combining the keto diet and OMAD can lead to additional weight loss, although keep in mind that doing them at once will be easier if you give yourself enough time to adjust to low-carb eating first.
2. Save time
It’s no secret that eating home-cooked meals is associated with better diet quality, spending time on planning and cooking can sometimes feel stressful (*).
Another benefit of OMAD is that it allows you to save time in the kitchen. By shrinking your eating period to 1 hour, you prepare food only once each day. It’s the perfect intermittent fasting plan for those who have busy schedules or would like to take a break from constant cooking — with the added benefit of weight loss and better health.
Here’s a tip: On top of getting work done, you can spend those extra hours on other activities that help you reach your goals faster. For example, hitting the gym if you can tolerate a fasted workout.
3. Protection against disease
As a form of intermittent fasting, OMAD counteracts obesity and slows the progression of cardiovascular disease, metabolic syndrome, hypertension, and type 2 diabetes.
When it comes to reducing your risk of heart disease, OMAD acts by reducing insulin levels.
According to a 2022 review article in Nutrients, “Insulin resistance is associated with a state of increased inflammation, including elevated C-reactive protein, decreased adiponectin, lower low-density lipoprotein (LDL) particle size, and additional metabolic factors that ultimately contribute to or are associated with development of atherosclerosis and coronary artery disease.” (*)
4. Autophagy
One might think that OMAD merely leads to calorie restriction, but it also results in a metabolic process called autophagy, which means “eating of self.” It’s when your damaged organelles (cell parts) are recycled in response to nutrient or energy starvation (*).
Without autophagy, our cells would not survive or would grow abnormally, which would lead to various diseases (*). It protects you from infections, cancer, aging, neurodegenerative diseases, and heart disease (*).
5. Beneficial for non-alcoholic fatty liver disease (NAFLD)
OMAD is one measure that mitigates non-alcoholic fatty liver disease, a condition seen in overweight or obese individuals in which fat builds up in their liver.
Aside from carrying excess weight, people develop this condition if they consume too much fructose, have type 2 diabetes and metabolic syndrome, and a diet high in simple carbs (*).
Although there is no drug treatment for NAFLD yet, the good news is that modifying your lifestyle, such as intermittent fasting and other forms of calorie restriction, can control or reverse fat buildup (*).
Is Eating One Meal a Day Safe?
Yes, OMAD is safe for most people and should not cause serious side effects except for increased hunger and cravings. Unless you are fat-adapted, you can experience keto flu symptoms, such as headaches, brain fog, and irritability. This signifies that your body hasn’t developed metabolic flexibility yet and that it’s looking for carbs.
For people who are diagnosed with diabetes (type 1 or type 2), fasting can lead to significant improvements in their Hemoglobin A1C. However, since not eating puts a patient at risk of hypoglycemia, they need to work with their healthcare provider. Discuss adjusting your medication dosages or finding a fasting plan that works for you, which may or may not include OMAD.
What Does Science Say About OMAD?
Reducing your eating time to just one meal a day has been shown to lower body mass and it allows you to become more metabolically flexible during exercise without affecting your performance. These findings are based on a 2022 study conducted on healthy lean individuals who ate three meals versus one meal a day between 5:00 and 7:00 pm for 11 days (*).
Other studies use shorter eating windows, which may help us appreciate OMAD.
For example, in a 2009 study, subjects were randomly assigned to a minimum fast of 20 hours per day (with a 4-hour eating window) or three meals a day (*).
Based on the results, the subjects’ weight and body fat mass were lowered in the fasting group but not in the group that consumed three meals. Moreover, those who fasted had lower triglycerides (93 vs 102 mg/dL) and higher HDL or good cholesterol levels (62 vs 57 mg/dL) (*).
How to Get Started with OMAD
It’s a good idea to begin with a shorter fast, for example a 12-hour fast, so that your body can adjust. Remember that you do not have to go all in right away. Try increasing your fast by one hour each week or every couple of days until you can comfortably fast for 23 hours.
In addition to easing into OMAD, follow these tips:
- Pick the right time: This depends on your schedule. For example, you can forgo breakfast and lunch, and break your OMAD fast at 6:00 pm if you work a typical 8-hour shift (from 9:00 am to 5:00 pm). Or, if you usually wake up hungry, then eat in the morning.
- Eat a healthy pre-fast meal: Consume foods high in vitamins and minerals that do not contain too many carbs. Limiting your carb intake before a fast will prevent filling your glycogen stores. Include proteins, healthy fats, and fiber. Examples are beef, fish, chicken, broccoli, cauliflower, and brussels sprouts.
- Stay hydrated: The good news is that zero-calorie drinks are not off-limits. Hydration is vital for your energy levels and mental performance all day. Drink water and zero-calorie electrolytes — Perfect Keto Daily Electrolytes, for example.
- Keep your stress levels low: Being stressed out makes you hungry and crave foods that are high in sugar. However, when you’re faced with stress and tempted to break your fast early, try stress-relief methods, such as walking, journaling, and meditation.
OMAD Sample Meal Plan
Ready to try OMAD? Check out these meals to break your OMAD fast that pack nutrients. Feel free to change them (for example, if you would like to add fruit as a dessert) as long as they’re easy to digest and contain substantial amounts of fat and protein. Fat is important for nutrient absorption (vitamins A, D, E, and K) while protein facilitates repair and recovery.
| Day | Meal | Side dish |
| 1 | Bone broth Ground beef with cabbage or string beans | Blueberries with whipped cream |
| 2 | Chicken in creamy garlic parmesan sauce | Avocado and cucumber salad |
| 3 | Baked salmon fillets with butter and lemon juice | Brussels sprouts or sauteed green beans |
OMAD Drawbacks
OMAD fasting doesn’t work for everyone. Some people find that they’re able to tolerate other types of intermittent fasts better than OMAD. Others would rather reduce their calorie intake each day than go without food.
A possible drawback is diarrhea or loose, watery stools when breaking the fast. This is because your body is more sensitive to food after hours of not eating.
Moreover, fasting all day and focusing on just one large meal may lead to binge eating and feeling a loss of control around food. If you have a history of an eating disorder, OMAD may not be right for you.
How Long Should You Do OMAD?
You can do OMAD one to three times per week and maintain that for as long as it’s benefiting you and you’re seeing results. Keep in mind that there is no reason to stick to a specific intermittent fasting plan if you find it difficult to sustain.
Also, pay attention to how you’re feeling. If OMAD is making you constantly tired, stressed, and deprived, you can always stop. It’s okay to try other fasting schedules or not fast at all.
FAQs
Discover more information about OMAD with the Q&As below.
What’s the best time to eat on OMAD?
It can be in the morning or evening when you can eat without distractions. If you choose to break your fast in the evening, make sure that it’s not close to bedtime to allow for digestion.
Does OMAD put you in ketosis?
Yes, it will, especially if your glycogen stores aren’t full when starting the fast and you engage in exercise — for instance, high-intensity interval training (HIIT) and running.
Who should not do OMAD?
People who are pregnant, breastfeeding, and have an eating disorder should steer clear of OMAD. Also, consult with your doctor if you’re interested in OMAD and you have a medical condition, such as diabetes.
The Bottom Line
As an intermittent fasting method, the OMAD diet is a more extreme version. It’s helpful for weight loss and overall health. Not to mention, it simplifies your day.
OMAD works well for most people, but it’s not for everyone. For those who would like to try one meal a day, we recommend easing into it. Pick a time to break your fast that works for you and consume whole, nutritious foods. There are no definitive rules on what your OMAD meals should be, but you’ll get the most out of this plan by making healthy choices.