It seems like new, trendy diets surface every week. Usually claiming to be the best eating method to attain optimal health, many are simply a slightly different version of a dietary pattern that already exists.
The OMAD diet is really no different…
However, compared to other derivative diets, OMAD is one of the most extreme examples. Although quite simple in theory, is OMAD safe or even feasible for the average person?
Let this serve as a guide to the benefits, risks, and appropriateness of the OMAD diet.
What Does OMAD Mean?
The acronym OMAD stands for “one meal a day” and is a form of time-restricted eating. More specifically, the OMAD diet includes only eating one meal per day of anything desired within a one-hour window. Feasting periods are most often at dinnertime and centered around exercise training.
If this seems like the extreme version of another popular diet plan known as intermittent fasting, that is because it is! The foundational premise of OMAD is an increased window of fasting.
But, rather than the typical fasting window of four, eight, or 16 hours, one fasts for 23 hours. This naturally includes sleep time and leaves a one-hour feeding window of unrestricted eating. Dieters are encouraged to eat an appropriate amount of calories to maintain health and foods high in micronutrients.
Yet, one of the main draws of this diet is being able to eat whatever one wants no matter the food’s quality. (All while still losing weight!)
The founders of the plan also suggest eating the meal at the same time of day each day to ensure a 23-hour fasting window. After all, this is the major distinguishing feature tied to the proposed health claims.
Is Eating One Meal a Day Healthy?
Generally speaking, eating one meal a day is not healthy for most individuals. This especially serves true for children, elderly, pregnant, or breastfeeding persons, and those who have a history of eating disorders.
Undoubtedly, eating one meal a day long term is not the ideal way to achieve health goals for anyone. Eating (usually multiple times a day) is a relational part of most cultures, which is important for mental and emotional health.
However, for a few specialized populations, this style of eating can offer benefits like providing the digestive system time to rest. But due to its newness, more research is needed to ultimately determine the validity of the proposed health benefits.
Potential Benefits & Risks
The research is very mixed about the efficacy and safety of eating one large meal per day as a long-term strategy, generally defined as one month and longer. Many sources claim a few athletes swear by the OMAD method, but they usually work with trained professionals and heavy oversight.
Seeking assistance from a qualified health professional is the best way to analyze the potential benefits and risks of OMAD. Or, really, any sort of dietary and eating pattern.
The main proposed, specific intermittent fasting benefits of OMAD include:
- Improved glucose tolerance
- Increased insulin sensitivity
- Aid in weight loss
- Gives the digestive system time to rest
- Promotes cell autophagy (implicated in reduced risk of chronic disease)
- Less food decision making
Conversely, the main risks of OMAD include:
- Increased blood pressure and/or cholesterol
- Hypoglycemia and resulting symptoms (dizziness, lightheadedness, etc.)
- Fatigue and lethargy
- Brain Fog or trouble concentrating
- Binge eating behaviors
- Macro and/or micro-nutrient deficiencies
- Decreased exercise performance
- Loss of social connection
Interestingly, anecdotal, experimental research also has noted an increase in willpower as a positive benefit. While this may jive with one’s personality and lifestyle, it is often better to not associate eating with willpower. This is particularly important for anyone with a history of an eating disorder.
Finally, if forced to answer, most health experts would probably agree that the risks of OMAD outweigh the benefits.
The Bottom Line
An extreme version of intermittent fasting, eating one meal a day (OMAD) is regularly touted as a simple, unconventional diet that may lead to weight loss.
While it may contribute further benefits similar to conventional intermittent fasting such as improved insulin sensitivity, it is not feasible or safe for many populations long term.
Following this diet short term every once in a while may benefit very few specific populations. However, working with a professional that provides frequent oversight is necessary.
Chander R. I tried extreme fasting by eating once a day — here’s what happened. Healthline.com. Published September 14, 2018. https://www.healthline.com/health/food-nutrition/one-meal-a-day-diet.
Southard L. What is the OMAD diet? Why eating one meal a day isn’t recommended by experts. Insider.com. Published March 13, 2020. http://www.insider.com/what-is-omad-diet.