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When exploring various forms of intermittent fasting, making a decision between Alternate Day Fasting vs OMAD (one meal a day) might be a hard choice if you haven’t done both, or you’re unsure of which worked best.11
So ultimately, the choice comes down to individual preferences, and station levels, and using this OMAD alternate day fasting combo instead of one or the other could be fruitful for some who are on the fence between the two.
Before starting a new eating plan, it is always important to consult a healthcare professional to ensure safety.
Analyzing Alternate Day Fasting (ADF) & One Meal a Day (OMAD)
There is a myriad of different types of intermittent fasting and although All Day Fasting and OMAD are both considered intermittent fasting, there are a number of differences between the two.
Alternate Day Fasting or All Day Fasting (ADF), in its strictest form, entails 36 hours of fasting followed by 12 hours of unrestricted eating. A more lenient approach includes a 24 to 36-hour fast, with the remaining 24 to 12 hours eating window. With ADF, assuming 3 meals are consumed within the non-fasting hours, an individual is consuming roughly 9-12 meals per week.
One Meal a Day, also known as OMAD, as its name suggests, restricts followers to one meal per day, typically consumed within a one-hour timeframe, with no calories for the remaining 23 hours. Some follow this plan but allow themselves up to 4 hours to eat, with the remaining hours of the day left to fast. When following OMAD, 7 meals will be consumed throughout the week.
Timing this meal is important due to the fact that the individual is only eating once per day. It may be beneficial to carry out the nighttime fast through breakfast and lunch and have a single meal for dinner once a majority of tasks are done for the day.
When comparing Alternate Day Fasting vs OMAD, although the timeframes are different, fasting still allows for beverages with zero calories such as coffee with no sweetener, creamer, or milk, unsweetened tea, and water. In fact, consuming water throughout a fast is a critical component that will ensure one’s health and well-being.
Is OMAD a Healthy Diet? What Are The Benefits?
As touched on above, One Meal a Day typically restricts eating to a one-hour timeframe. During this time, an individual is tasked with consuming a healthy amount of calories (no less than 1,200). It is imperative that this meal includes nutrient-dense foods that will sustain the body and give it the vitamins and minerals needed.
The benefits of OMAD include:
- Health: A study referenced in the National Library of Medicine followed 15 subjects (aged 40-50 between body mass index of 18 and 25) for 8 weeks and found the individuals consuming only one meal a day lost more weight and had a lower blood glucose reading regardless of consuming the same food, just in a different time frame.2
- Simplicity: Eating only once a day removes the constant cycle of food-focused thoughts and time spent on meal preparation and clean-up. According to the U.S. Department of Agriculture, most Americans spend nearly 40 minutes preparing, serving, and cleaning up food per day.3 With less of a spotlight on food, individuals can allocate their time to more productive tasks or relaxation.
- Affordability: Because individuals are only eating one meal a day, the likelihood of a lower grocery bill is probable. Those following OMAD may also be less likely to snack as frequently as they once had, which will also cut down on food costs.
Is a 24 Hour Fast Safe? Potential Downsides of OMAD
There are few things in life that do not come with a pro and con list; and although the One Meal a Day way of eating has an enticing list of benefits, there are some potential downsides that should be noted.
Physiological Effects: Most people eat throughout the day, therefore, their bodies are used to incrementally processing food. With OMAD, because all food is eaten in one sitting, it can potentially put a strain on the body causing:
- Digestive issues, such as stomach pain, constipation, or diarrhea
- Lightheadedness or nausea, which is both signs of low blood sugar or low blood pressure
- Exhaustion or lethargy due to reduced energy consumption
- Extreme hunger that causes stomach pain4
Psychological Effects: Extreme changes in eating habits can affect emotions and moods. Reducing meals to once a day can:
- Lead to lack of concentration and prompts obsessive behavior and thoughts in regard to food or lack of food
- If consumed too early, cause an individual to break their fast later in the day
- Cause mood swings, anxiety, and depressive thoughts5
- Precipitate binge eating and other disorders due to the extreme restriction of food, which was documented in a study found in the National Library of Medicine6
- Promote overeating by trying to force a large amount of calorie consumption into a relatively small timeframe
- Reduce social interaction by removing opportunities to associate with colleagues, friends, and family during meals, which can cause feelings of isolation or loneliness
Is Alternate Day Fasting Safe? Are There Any Benefits?
Alternate Day Fasting pushes past the 24-hour mark that OMAD incorporates and employs a 24 to 36-hour fasting window. Essentially, the time given to consume food is limited to every other day between 12 and 24 hours. When using ADF as a tool for health and weight loss, safety is fundamental.
When participating in an Alternate Day Fasting plan, it’s important to eat balanced meals to ensure health and safety. If individuals go 48 to 72 hours without food, their body can begin to lose vitamins and minerals; so, when fasting for up to 36 hours, ensuring the replacement of those nutrients is essential.
The benefits of ADF are similar to OMAD, with some differences due to the length of time fasting.
- A clinical trial found in the National Library of Medicine reported that fat loss in participants increased after participating in the alternate day fasting for 22 days. Subjects lost between .5 and 2.5% of their starting body weight in this time frame.7
- Alternate Day Fasting provides the ability to go an entire day at a time without planning or preparing food. Having the ability to go without breaking for meals can free up significant time that can be used for other tasks.
- A significant amount of calories will be cut from the week due to Alternate Day Fasting, which not only results in weight loss but a reduction in the amount of money spent on food. Forgoing food for 3 to 4 days per week could reduce food costs by up to 40%.
Potential Downsides of Alternate Day Fasting
Just as One Meal a Day has its potential downsides, Alternate Day Fasting does as well. In fact, because of the potential extended fasting times, some of the effects may be more pronounced, such as:
- Extreme hunger
- Lack of energy
- Lack of self-control
The clinical trial regarding ADF, mentioned above, reported that as the study went on, the hunger levels of the participants always remained the same on fasting days and never diminished. So, while the fat loss was accomplished, unfortunately, the desire to eat doesn’t fade.
Another notable issue that may disqualify someone from a strict Alternate Day Fasting protocol is having to take a daily medication with food. Skipping medication because of a fast is ill-advised and should never be done without approval from a doctor.
In addition, most multivitamins suggest consuming with food since many vitamins are fat soluble so ADF may not be best for nutrient timing through supplementation either.
Exercise While Alternate Day Fasting or OMAD
Working out and lifting weights is smart to incorporate into any healthy routine, but before jumping in, it is important to evaluate how these fasting plans affect energy levels. A common routine for many athletes is to consume carbs before a workout to ensure they have strength and stamina while exercising.
Because Alternate Day Fasting and OMAD have large portions of time where no food is eaten, energy levels may be waning when it is time to work out, which could not only result in poor performance but cause an individual to become lightheaded and dizzy.
Adjustments to a workout schedule may need to be made to accommodate energy needs. For example, it might be advantageous to modify heavy exercise days to line up with times when the body has enough fuel to avoid overexertion or injury.
Again, when starting a new eating plan, especially when including exercise, it is critical that a doctor evaluates health beforehand to ensure safety.
Which One Will You Lose Weight Faster On: (ADF) vs One Meal a Day (OMAD)?
A big motivator for trying Alternate Day Fasting or One Meal a Day is a prospect of quickly losing weight quickly while eating instead asking “If you starve yourself, how long to lose weight?” If choosing to sacrifice eating for large timeframes, knowing which plan will have the fastest and most effective results is important.
When practicing OMAD vs alternate day fasting, individuals typically compress a large number of calories into a fixed timeframe of about an hour. Depending on the number of calories eaten prior to trying One Meal a Day, this may not equate to a calorie deficit or where you burn more calories than consumed. As mentioned earlier, research does show success in losing weight on OMAD, but unless a calorie deficit is reached, the progress could be slow.
But don’t be frightened because a calorie deficit without exercise is achievable. Although exercise can help you to eat more and still stay in a deficit as well as expedite weight loss results.
Alternate Day Fasting has the likelihood of faster results due to completely cutting out 3 to 4 full days of calories per week. Making up or supplementing calories in response to fasting days is not encouraged during ADF. On days that eating is allowed, even if an individual consumes more than a typical daily allotment of calories, there is a higher chance of ending with a weekly calorie deficit.
Both of these fasting routines also have the potential to push the body into ketosis, which is a metabolic state that tells the body to burn ketones from fat instead of glucose from the liver because it is possible to reach ketosis after fasting for only 12 hours.1
The body will continue to operate in ketosis and burn fat, until glucose is introduced, which happens during the consumption of carbohydrates. Alternate Day Fasting allows for a longer period in ketosis than OMAD and prolongs the time the body is focused on burning fat.1
Regardless of being in ketosis, it is important to remember that calories in versus calories out will be the ultimate factor in weight loss.
Which is Better: Alternate Day Fasting vs OMAD?
When trying to choose between One Meal a Day vs Alternate Day Fasting, looking into personal habits, routines, and hang-ups could help in making a decision.
For some, OMAD could fit into their work/life balance and simplify their lifestyle by not having to think about food for the majority of the day. At the same time, others may find Alternate Day Fasting works into their routine better because food only has to be planned around 3 to 4 days a week.
According to multiple users on a Reddit thread, Alternate Day Fasting helps them take the focus off food for an entire day at a time, while the next day, they can follow a normal eating pattern. These same individuals suggest that when they tried OMAD, it caused them to obsess and stress about their one meal a day and perpetuated a binge eating mindset.8
If these ways of eating are unfamiliar, breaking down the basics of Alternate Day Eating vs OMAD can direct individuals to a plan that suits them.
|One Meal a Day
|Alternate Day Fasting
|Fasting Time Frame
|20 – 24 Hours
|24 – 36 Hours
|Eating Time Frame
|1 – 4 Hours
|12 – 24 Hours
|Food Goals / Restrictions
|At least 1,200 well-balanced calories per meal
|Well-balanced food with no calorie restrictions
|The simplicity of only having to prepare and clean up one meal per day
|Significant weight loss could be achieved due to calorie deficit as well as physiological changes
|Potential to trigger binge eating and other disordered eating habits
|Likelihood of extreme hunger and possibility of fatigue from lack of calories on fasting days
Try a Combination of OMAD and ADF
Being too stringent on eating plans can backfire, so finding a livable solution is key; this may come in the form of combining One Meal a Day and Alternate Day Eating.
The final outcome may not be “by the book”, but taking the time to find a workable plan will make achieving goals that much easier. To assess what works best, it may be beneficial to conduct trial periods by using the following steps.
- Step 1: Begin by committing to Alternate Day Fasting for one week
- Step 2: Throughout the week, make notes regarding the difficulties that are encountered
- Step 3: At the beginning of the next week, switch to One Meal a Day
- Step 4: Like the previous week, note where the biggest challenges lie
- Step 5: At the conclusion of this week, compare notes regarding Alternate Day Fasting vs OMAD and adjust the plan
- Step 6: Potentially combine the two within the same week. See below for more details
Step six can take on many forms; for instance, if making it through 36 hours without eating was too difficult of a challenge during the trial period, then the adjustment might be that during the fasting day, add a single, low-calorie meal.
Alternatively, One Meal a Day might work decently, during the week, but the weekend could prove to be difficult; so, adjusting weekends to one day of fasting and one day of eating could be a novel way to tie in Alternate Day Fasting with OMAD.
The different types of intermittent fasting each have their positives and negatives; so when comparing Alternate Day Fasting vs OMAD, it’s less about making the correct decision and more about finding, or creating, the best plan that helps achieve the desired goal.
To see what works best for any given lifestyle, try one out and then try the next before potentially combining the two.
1National Institute on Aging. (2020, February 27). Research on intermittent fasting shows health benefits | National Institute on Aging. National Institute on Aging. Retrieved July 22, 2022, from <https://www.nia.nih.gov/news/research-intermittent-fasting-shows-health-benefits>
2Stote, K., Baer, D., Spears, K., Paul, D., Harris, K., Rumpler, W., Strycula, P., Najjar, S., Ferrucci, L., Ingram, D., Longo, D., & Mattson, M. (2009, February 20). A controlled trial of reduced meal frequency without caloric restriction in healthy, normal-weight, middle-aged adults. NCBI. Retrieved July 22, 2022, from <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2645638/>
3Hamrick, K. (2016, November 7). Americans Spend an Average of 37 Minutes a Day Preparing and Serving Food and Cleaning Up. USDA ERS. Retrieved July 22, 2022, from <https://www.ers.usda.gov/amber-waves/2016/november/americans-spend-an-average-of-37-minutes-a-day-preparing-and-serving-food-and-cleaning-up/>
4Migala, J., & Kennedy, K. (2021, November 18). OMAD Diet: Safety, Health Benefits, Risks, and More. Everyday Health. Retrieved July 22, 2022, from <https://www.everydayhealth.com/diet-nutrition/omad-diet/>
5Kay, I. (2019, October 21). Is Your Mood Disorder a Symptom of Unstable Blood Sugar? University of Michigan School of Public Health. Retrieved July 22, 2022, from <https://sph.umich.edu/pursuit/2019posts/mood-blood-sugar-kujawski.html>
6Stice, E., Davis, K., Miller, N., & Marti, C. (2008, November). Fasting Increases Risk for Onset of Binge Eating and Bulimic Pathology: A 5-Year Prospective Study. NCBI. Retrieved July 22, 2022, from <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2850570/>
7Ravussin, E. (2005, January). Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism. PubMed. Retrieved July 22, 2022, from <https://pubmed.ncbi.nlm.nih.gov/15640462/>
8Various. (2020, September 20). OMAD VS ADF? : r/AlternateDayFasting. Reddit. Retrieved July 22, 2022, from <https://www.reddit.com/r/AlternateDayFasting/comments/iw6gr2/omad_vs_adf/>
9Smeh, Nikolay. “egg on white ceramic plate photo – Free Food Image on Unsplash.” Unsplash, 16 September 2020. Accessed 6 April 2023. <https://unsplash.com/photos/gPpbFaEkl00>
10Pexels–2286921. “Alarm Clock and Mug.” Canva. Accessed 6 April 2023. <https://www.canva.com/photos/MADQ4yOlRn0-alarm-clock-and-mug/>
11CharlieAJA. “Keto fasting concept.” Canva. Accessed 6 April 2023. <https://www.canva.com/photos/MADvL4VjbMQ-keto-fasting-concept/>