The One Meal a Day Diet for People with Diabetes

Article written and reviewed by Cyrus Khambatta, PhD
Published January 19, 2022

OMAD is a form of intermittent fasting that stands for “One Meal A Day.

As the name explains, this dietary strategy involves eating a day’s worth of calories in one meal, while drinking water and zero-calorie beverages like green tea the rest of the time.

OMAD is frequently recommended as a weight loss plan, as well as a form of treatment for type 2 diabetes, primarily due to the myriad health benefits of intermittent fasting.

In this article, we’ll explain the significant health benefits that One Meal A Day promotes, as well as some of the potential side effects and pitfalls of which to be aware.

Then, we’ll touch on a recommended meal plan that can replicate the benefits of One Meal A Day, while minimizing its risks and side effects.

And finally, we'll explain some alternative forms of intermittent fasting that may be better for you!

What Is the OMAD Diet?

The OMAD diet (or One Meal A Day diet) is a dietary strategy in which, as the name explains, you eat only one meal a day, within a single window that lasts approximately one hour.

As one of the many forms of intermittent fasting, OMAD takes advantage of several of your body’s natural adaptations by creating a clearly defined eating window and an extended fasting window.

The difference between One Meal A Day and several other forms of intermittent fasting lies in the balance of the fasting and eating window.

Where other strategies — like the 16:8 method or 24 hour fast method — change your meal frequency and emphasize long periods without eating, OMAD condenses all eating into a single meal.

When it comes to implementing a smart, effective One Meal A Day diet, the most important consideration is doing so in a sustainable way.

Eating only once per day requires large meals and larger-than-normal portion sizes, which can create a few obstacles.

What Is the Best Time to Eat One Meal a Day?

There are numerous opinions and strategies on when it’s best to eat your one meal a day. Breakfast? Lunch? Dinner? Snack? Midnight? However, most of the scientific backing on calorie restriction and intermittent fasting simply emphasizes that there is a time window of fasting, rather than when this period of time occurs.

There are also few arguments about One Meal A Day regarding how rigorously to restrict your caloric intake. For example, some experts recommend that if you keep a four hour eating window each day, you'll experience major benefits, while others advocate a strict OMAD diet where all caloric intake is confined to one meal.

Our recommendation for performing the One Meal A Day diet is to choose a time during the day that works best for you, and focus on consistently eating within a few hours of that same time every day.

What Are the Health Benefits of Eating One Meal a Day?

When you do the OMAD diet correctly, there are a wide variety of health benefits, drawing from three major factors.

First, it is easier to maintain a calorie deficit when eating only once per day, which in turn will help you lose weight sustainably. and since there are many benefits to losing weight, it's often worth considering!

Secondly, when eating only once per day, it’s often less tempting to eat fried and packaged foods and instead eat foods that are known to promote optimal metabolic health.

Third, there is a biological process called autophagy that your body enters during a fasted state that is very beneficial to your body.

Once your body has digested, absorbed, and transported the nutrients present in a single meal, cells in tissues all around your body are forced to oxidize (burn) the fuels they have stored over time.

This form of biological ‘recycling’ is one of the primary benefits of intermittent fasting, and occurs during many IF strategies (16:8, 24 hour, or 5:2).

The OMAD Diet for Weight Loss

The OMAD diet can be a very effective technique at helping you lose weight, because — as the name describes — you only eat to satiation once per day.

By doing this, you’re likely to find that it’s very challenging to eat your daily calorie requirement in a single meal.

In turn, this results in a daily calorie deficit, and those fewer calories then translate into weight loss and fat loss.

The OMAD Diet for Insulin Resistance and Type 2 Diabetes

The OMAD Diet can be a hugely beneficial technique for people living with diabetes to reduce their blood glucose, body weight, and insulin concentrations, especially when paired with a proper diabetes diet.

The reason is simple: fasting is excellent for diabetes. In addition to its weight-loss and fat-loss benefits, both of which improve insulin resistance, OMAD also makes diabetes management a simpler process.

In the absence of food, it’s easier to control your fasting glucose, fasting insulin, and A1c, all of which improve your diabetes health.

Insulin concentrations remain low most of the day because insulin is mainly secreted in response to food intake, and when you fast then the biological need to secrete insulin is greatly reduced.

Especially for people injecting insulin using an insulin pump, syringe, or pen, OMAD requires less bolus (mealtime) injections, and increases your dependence on basal insulin only.

Persistent Hunger and Disordered Eating

Many people suffer from persistent hunger, for various reasons. People who feel hungry frequently often report that they feel “hostage“ to their kitchen and are constantly “foraging” for their next meal.

The OMAD diet is a very effective solution for this problem because eating only one meal per day trains the appetite control center in your brain to only expect nutrients once per day.

While this does not work for every individual, many people find that just like their muscles, their brain is a very “trainable” organ that can alter its function under the right circumstances.

The OMAD Diet for Blood Pressure and Cholesterol

There has been some promising research that OMAD and other forms of intermittent fasting also have a beneficial effect on your blood pressure and cardiovascular health.

One study found a promising correlation between intermittent fasting and blood pressure, along with numerous other benefits for type 2 diabetes.

It’s important to note, however, that OMAD by itself does not necessarily increase your health. One study found that the OMAD diet without calorie restriction or a specific diet had little or negative repercussions on cardiovascular health, likely due to overeating at a single daily meal.

Below, we’ll explore some of the ways that the OMAD diet can go wrong, and discuss how to maximize the benefits of this eating pattern and minimize any potential side effects.

Is Eating Just One Meal a Day Bad for You?

The human body is capable of fasting for many days at a time, so from that perspective performing OMAD is not considered dangerous.

However, there are a few side effects to be aware of with the OMAD if not executed correctly, which we’ll explore below.

Throughout this entire process, it can be very helpful to work with a nutritionist or dietician. Everyone is different, and working with a trained professional will always be more targeted than any information we can provide.

Note: If at any point, you start to notice unexpected physical effects, stress, or psychological strain from eating a One Meal A Day diet, this diet may not be right for you.

One Meal a Day Doesn’t Mean “Eat Anything”

People who engage in OMAD eat a single meal containing all of their daily calories. In order to meet their target calorie intake, people often gravitate towards eating foods with a high-calorie density or eating foods that are high in dietary fat, including foods like meat, chicken, fish, eggs, cheese, avocados, nuts, seeds, and vegetable oils.

In the search for enough calories, other people gravitate towards eating packaged and refined foods like donuts, crackers, chips, sodas, and pastries and argue that “it doesn’t matter what I eat because I’m only eating once per day.”

In effect, the One Meal A Day diet strategy can sometimes lead people to sacrifice food quality for quantity.

Scientific research has clearly shown that a high intake of animal foods, high-fat foods, and/or refined foods can all independently contribute to an increased risk for many chronic diseases, including:

Finally, sometimes people who engage in OMAD overeat their calorie intake in their one meal per day, which can result in fatigue, weight gain, and increasing their risk for chronic diseases, despite the fact that they are fasting for the majority of the day.

Low Blood Glucose

Eating only one meal a day will naturally result in periods of lower blood glucose, along with the natural lowering of blood sugar levels that results from weight loss and reduced insulin resistance.

So for those living with low blood glucose (hypoglycemia), OMAD can be very challenging because it will likely only exacerbate their symptoms.

Physical and Mental Challenges

Psychologically, it can be challenging to prepare for many hours of fasting, and without knowing it, many people “binge eat“ during their single daily meal, creating a daily habit that can lead to disordered eating, and uncomfortable gastrointestinal symptoms including gas, bloating, constipation, diarrhea, or abdominal pain.

People with eating disorders, or simply people who do lots of physical activity throughout the day may also find it difficult or impossible to eat OMAD.

As we mentioned above, for some people the One Meal A Day diet may simply not be the right dietary plan, especially if you start to notice excessive stress, unhealthy weight loss, or physical strain (which can dramatically reduce your quality of life in the long-term).

OMAD for Women

One thing to be aware of is that women and men respond differently to intermittent fasting.

Most research shows that OMAD can be therapeutic and benefit women’s health, weight, and cardiovascular factors and has limited or negligible side effects.

However, changing your diet can impact the many aspects of your body, so if you’re pregnant or trying to get pregnant then please consult with your doctor before trying OMAD.

Currently, there are no studies done on intermittent fasting in pregnant women due to ethical concerns, and most recommendations suggest to avoid OMAD while pregnant altogether.

Pregnancy can affect your dietary schedule, and everyone responds to pregnancy differently, so focusing on proper nutrition and other dietary concerns for your baby should most likely take precedence over a set OMAD schedule.

OMAD Meal Plan

As we mentioned above, OMAD by itself doesn’t necessarily maximize your health benefits. After all, OMAD just means “One Meal A Day”, which could feasibly include everything from plant-based diets to carnivore diets to diets composed entirely of SPAM and soda. 

However, certain diets will emphasize the health benefits of OMAD far more than others.

  • High-fat, low-carb diets (like the ketogenic diet ) provide some short-term benefits like weight loss but have disastrous long-term ramifications for your diabetes health.
  • Vegan diets are a step in the right direction by eliminating risk factors from meat, but allow for processed foods and sweeteners, which increase your risk for various diseases.
  • Perhaps worst is the “standard American diet”, which includes heavy meats, processed foods, and fats, which likely contributes to the continuous increase in chronic disease in America.

The Low-Fat, Plant-Based, Whole-Food Diet

The one diet that consistently amplifies the benefits of OMAD is a low-fat, plant-based, whole-food diet. Combined with One Meal A Day (or other forms of intermittent fasting), and daily exercise, this powerful diet can enhance your health, promote weight loss, and boost your fitness and energy, while drastically reducing your risk for chronic disease.

Five Days of Low-Fat, Plant-Based, Whole-Food OMAD

One of the biggest challenges of switching to a low-fat, plant-based, whole-food diet is feeling like you’re giving something up. This plant-based sushi-bowl alternative doesn’t feel like you’re giving anything up, and is a filling and satisfying meal for the day!

Warming Winter Squash, Potatoes, and Lentils

Another challenge people list when switching to plant-based nutrition is that they feel like they’re missing out on those warming, winter dishes. With this warming winter squash, you’ll see exactly how satisfying plants can be.

fruit bowl topped with chia seeds

One of the best parts of plant-based, whole-food proteins is that sometimes it feels darn-near-like cheating! With candy-sweet fruits, this all-day energy bowl is filled with the high energy to keep you going throughout the day. Other alternatives include adding oatmeal or other grain options!

rice bowl loaded with green veggies

Smoky, rich, and filled with punchy flavors. Not descriptors that are commonly associated with plant-based nutrition, which is part of the problem. Reward your pallet with a meal packed with flavor and taste.

Day 5 — Acai Bowls

Antioxidant Acai Bowl

We’ll emphasize again: with green-light foods on the low-fat, plant-based, whole-food nutrition, you can eat as much as you want. Take full advantage with acai bowls packed with as much fruit, flavor, and nutrition as you care to eat.

Choosing Your Form of Intermittent Fasting

One thing we also want to address is that, for some people, the OMAD diet may not be the right form of intermittent fasting diet for you. After all, there is a wide range of different ways to restrict your calorie intake into a small eating window without limiting yourself to just one meal.

Below, we'll explore a few of the different ways to tailor your eating pattern and eating habits to your unique needs.

I Want to Lose Weight

One of the main reasons many people chose to try intermittent fasting is to lose weight. And it's hard to argue with this goal -- if you have a body mass index above average, weight loss has been proven to improve your blood pressure, improve your blood sugar levels, and boost your energy (plus make you feel better and feel more confident!)

If you're looking to lose weight, the One Meal a Day diet is a helpful method, if you can combine it with a healthy diet and a calorie deficit/calorie restriction. After all, this eating pattern creates a large fasting window every day.

However, it's important to have a plan for transitioning away from One Meal A Day after you reach your target weight. There are numerous cases of healthy adults who diet extensively to reach a "normal weight", and then immediately experience significant weight gain that "rubber bands" them right past the same problems!

The goal here isn't temporary weight loss. It's to lose weight for good!

I Want to Reverse Insulin Resistance

Another of the main reasons people choose intermittent fasting is to reverse insulin resistance and diabetes.

And we heavily recommend intermittent fasting for this purpose! After all, extended periods of calorie restriction help your body focus on burning through those fat stores and improving your insulin sensitivity. The weight loss and improved energy are a nice plus too!

But we don't recommend One Meal a Day if you're intermittent fasting to reverse insulin resistance. This is because we recommend a low-fat, plant-based, whole-food diet while you're working to reverse insulin resistance, and with these calorie-light foods, it can be hard to get enough nutrients for the whole day in just one short sitting.

Rather than eating the One Meal a Day diet, we recommend a 16:8 (where you just don't eat breakfast!) or twice-a-week 24 hour fast here, which keeps the calorie restriction you're looking for while also giving you time to get enough nutrients (which you might not have when just eating One Meal a Day).

I Want to Improve My Overall Health

This is a great reason to start intermittent fasting. As we mentioned before, intermittent fasting can help you lose weight, improve your cholesterol and blood pressure, and reduce your oxidative stress (bringing in all of the other benefits that come with it!)

For this kind of goal, we recommend starting with one of the "easier" forms of time-restricted eating, like fasting one day a week for 24 hours, or the 16:8 method we mentioned above.

Starting with these slightly easier forms of caloric restriction can yield some steady results (like healthy weight loss and better cardiovascular health), without risking the possibility of binge-eating or overeating when you're re-feeding.

I Want to Form Good Habits for the Future

And finally, if you're just looking into intermittent fasting and time-restricted eating as a way to form good habits for the future -- whether that's getting ahead of the game before you need weight loss, supporting your immune system and overall health through autophagy, or staying on top of your health conditions, the answer is -- whichever works for you!

Ultimately, the best form of time-restricted eating is the one that you can stick to, whether that's the OMAD diet, a 16:8 intermittent fasting plan, 24 hours once or twice a week, or some other form of caloric restriction.

Because whether you eat one meal a day or several, the important part of getting results is that you stick to your goals and find a plan that works for you and your lifestyle for an extended period. Do that, and all of the weight loss, health benefits, and more will come in time.

Learn from the Experts

Here at Mastering Diabetes, we've got a pretty good sense for intermittent fasting, because it's one of the core ways we recommend reversing insulin resistance and working to improve your life if you're living with diabetes.

And while One Meal a Day isn't always the easiest form of caloric restriction if you're looking to eat a low-fat, plant-based, whole-food diet that reverses diabetes, it definitely has some benefits in the long term if you can make it work!

Still, finding your way through the complicated world of living with diabetes can be stressful! That's why we want you to know that you're not alone.

Our expert coaches have been trained extensively in how to help reverse insulin resistance and master diabetes and can help provide you with dietary, exercise, and nutritional guidance.

Now, no one besides your doctor or personal specialist can provide medical advice that's specific and tailored to you, but there's a reason that hundreds of people have experienced what we like to call an "A1c Miracle."

It's because this method actually works.

Will you be the next success story?

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About the author 

Cyrus Khambatta, PhD

Cyrus Khambatta, PhD is a New York Times bestselling co-author of Mastering Diabetes: The Revolutionary Method to Reverse Insulin Resistance Permanently in Type 1, Type 1.5, Type 2, Prediabetes, and Gestational Diabetes.

He is the co-founder of Mastering Diabetes and Amla Green, and is an internationally recognized nutrition and fitness coach who has been living with type 1 diabetes since 2002. He co-created the Mastering Diabetes Method to reverse insulin resistance in all forms of diabetes, and has helped more than 10,000 people improve their metabolic health using low-fat, plant-based, whole-food nutrition, intermittent fasting, and exercise.

Cyrus earned a Bachelor of Science in Mechanical Engineering from Stanford University in 2003, then earned a PhD in Nutritional Biochemistry from the University of California at Berkeley in 2012. He is the co-author of many peer-reviewed scientific publications.

He is the co-host of the annual Mastering Diabetes Online Summit, a featured speaker at the Plant-Based Nutrition and Healthcare Conference (PBNHC), the American College of Lifestyle Medicine Conference (ACLM), Plant Stock, the Torrance Memorial Medical Center, and has been featured on The Doctors, NPR, KQED, Forks Over Knives, Healthline, Fast Company, Diet Fiction, and the wildly popular podcasts the Rich Roll Podcast, Plant Proof, MindBodyGreen, and Nutrition Rounds.

Scientific Publications:

Sarver, Jordan, Cyrus Khambatta, Robby Barbaro, Bhakti Chavan, and David Drozek. “Retrospective Evaluation of an Online Diabetes Health Coaching Program: A Pilot Study.” American Journal of Lifestyle Medicine, October 15, 2019, 1559827619879106. https://doi.org/10.1177/1559827619879106

Shrivastav, Maneesh, William Gibson, Rajendra Shrivastav, Katie Elzea, Cyrus Khambatta, Rohan Sonawane, Joseph A. Sierra, and Robert Vigersky. “Type 2 Diabetes Management in Primary Care: The Role of Retrospective, Professional Continuous Glucose Monitoring.” Diabetes Spectrum: A Publication of the American Diabetes Association 31, no. 3 (August 2018): 279–87. https://doi.org/10.2337/ds17-0024

Thompson, Airlia C. S., Matthew D. Bruss, John C. Price, Cyrus F. Khambatta, William E. Holmes, Marc Colangelo, Marcy Dalidd, et al. “Reduced in Vivo Hepatic Proteome Replacement Rates but Not Cell Proliferation Rates Predict Maximum Lifespan Extension in Mice.” Aging Cell 15, no. 1 (February 2016): 118–27. https://doi.org/10.1111/acel.12414

Roohk, Donald J., Smita Mascharak, Cyrus Khambatta, Ho Leung, Marc Hellerstein, and Charles Harris. “Dexamethasone-Mediated Changes in Adipose Triacylglycerol Metabolism Are Exaggerated, Not Diminished, in the Absence of a Functional GR Dimerization Domain.” Endocrinology 154, no. 4 (April 2013): 1528–39. https://doi.org/10.1210/en.2011-1047

Price, John C., Cyrus F. Khambatta, Kelvin W. Li, Matthew D. Bruss, Mahalakshmi Shankaran, Marcy Dalidd, Nicholas A. Floreani, et al. “The Effect of Long Term Calorie Restriction on in Vivo Hepatic Proteostatis: A Novel Combination of Dynamic and Quantitative Proteomics.” Molecular & Cellular Proteomics: MCP 11, no. 12 (December 2012): 1801–14.

Bruss, Matthew D., Airlia C. S. Thompson, Ishita Aggarwal, Cyrus F. Khambatta, and Marc K. Hellerstein. “The Effects of Physiological Adaptations to Calorie Restriction on Global Cell Proliferation Rates.” American Journal of Physiology. Endocrinology and Metabolism 300, no. 4 (April 2011): E735-745. https://doi.org/10.1152/ajpendo.00661.2010

Bruss, Matthew D., Cyrus F. Khambatta, Maxwell A. Ruby, Ishita Aggarwal, and Marc K. Hellerstein. “Calorie Restriction Increases Fatty Acid Synthesis and Whole Body Fat Oxidation Rates.” American Journal of Physiology. Endocrinology and Metabolism 298, no. 1 (January 2010): E108-116.