The search continues for the optimal eating method for weight management and health. Is One Meal a Day fasting (OMAD) the answer to that quest or unnecessary torture?
Let’s cover OMAD fasting, discuss any benefits, and see what the research says.
What is OMAD fasting?
One meal is eaten daily, typically in the evening.
OMAD fasting is an emerging trend in the fitness world and is gaining traction elsewhere because of its simplicity.
Supporters say OMAD promotes weight loss and has other health benefits. But is it worth being hungry all day? And is it healthy to only eat one meal a day? OMAD is not for everyone. Here’s what you should know before trying an OMAD fast.
The “Fasting Window.”
A fasting window is a time in the day when no calories are eaten.
Every fasting plan has a “fasting window.” OMAD fasting is the most extreme form of intermittent fasting. With OMAD, you eat for only one hour a day, leaving 23 hours without food. This is also called 23:1 fasting. There are no specific rules about what foods to eat during the hour.
Some people practice OMAD every day, while others do it a few times a week. Many use it to break through weight loss plateaus, which are times when weight loss seems to stall.
OMAD is less popular than other types of intermittent fasting. More common fasting plans allow two or three meals within a 24-hour period. There are several types of intermittent fasting, each with different fasting windows. The 16:8 plan is the most widely used, with 16 hours of fasting and 8 hours for eating.
Related Article: Fasting Mimicking Diet; What Is It?
Benefits of OMAD fasting
Benefits of OMAD fasting include less time for meal preparation and less money spent on food.
It is difficult to eat as much in your 1-hour window compared to eating throughout the day. Less food = less expense and, with only eating one hour of the day, meal prep time is drastically reduced.
OMAD & Weight Loss
Does it help people lose more weight?
The effect of meal frequency on weight has been studied, and the body of research is growing. (1). One study looking at meal frequency found that eating only 1 or 2 meals per day was associated with decreased BMI ( body mass index) compared to eating three or more meals per day. A lower BMI* is typically good and indicates a healthy weight.
This same study also looked at meal timing and found that people eating their largest meal at breakfast had a drop in BMI than those eating their largest meal at lunch or dinner (2).
Fewer meals earlier in the day meant more weight loss in this study. So, eating one meal in the evening, as most people do on an OMAD diet, may or may not be beneficial.
Another factor to consider is the regularity of a person’s daily eating. Does the “eating window” time occur at a similar time each day, or is it unpredictable? One study compared the number of meals eaten in a day and whether the meals were eaten at the same time each day or at various times. People who ate in a predictable pattern consumed fewer calories, regardless of how many meals were eaten. Eating meals at predictable times was beneficial for weight maintenance (4).
While studies on intermittent fasting and weight loss show benefit, there is currently no research looking specifically at OMAD and weight loss.
*BMI 18-25 is ideal. Typically, below 18 is underweight, over 25 is considered overweight.
Is OMAD Better Than Other Forms Of Fasting?
There is a rapidly growing amount of research on the benefits of fasting, but none explicitly compares one meal a day fasting to other forms.
Risks of OMAD
Nutritional deficiencies With limited food intake, the risk of nutrient deficiencies is high.
Exercise While exercise during fasting can be done, heavy training during prolonged fasting may lead to muscle breakdown.
An unhappy stomach Some people experience cramping or stomach pain with eating after prolonged periods of fasting. Others may have diarrhea or loose stools.
Increased blood sugar OMAD fasting has been found by one study to increase fasting glucose (5). This is in direct contrast to intermittent fasting, which has been found to improve fasting glucose (6).
Medication concerns. Some medications need to be taken with food. If they are taken several times a day, this is not possible with OMAD.
Social isolation It is challenging and socially isolating to follow a plan where you can no longer share most meals, happy hours, or birthday parties eating with friends and family.
Who should not try OMAD fasting?
- Children
- Elderly people
- Pregnant women
- Anyone with a history of disordered eating
- Diabetics
- Underweight individuals
Key takeaways: OMAD Fasting
OMAD may help some people lose weight, but it is not without risk, and specific populations should avoid it altogether.
There are many benefits to intermittent fasting, but it isn’t the right fit for some people, and the research on OMAD specifically is scant.
Even if you don’t fall into one of the categories that should never try OMAD, it may not be for you. If you experience persistent symptoms such as dizziness, headaches, fatigue, and nausea, skip OMAD.
Perhaps the most significant takeaway from these questions about OMAD is the importance of personalized recommendations. We all have different genetics, lifestyles, and goals; nutrition recommendations need to be personalized and evidence-based. There is more than one “right” way to eat!
