OMAD, which stands for One Meal A Day, is a popular way to eat that many people use to lose weight and improve their metabolic health. Is it sustainable and healthy way to lose weight? Is it a long-term healthy lifestyle? This guide will help answer all these questions and help to determine if OMAD is the right choice for you.
What is OMAD?
Simply stated, OMAD is one meal per day. It doesn’t tell you what to eat or when you should eat. It only tells you how many times to eat.
OMAD (or the longest time-restricted form of eating) is equivalent to a 23/1 fast, which involves fasting for 23 hours while eating within a 1-hour window. OMAD does not restrict calories or prescribe a specific macronutrient combination. We encourage you to continue eating a healthy, low-carb meal at this time. For more practical tips on eating OMAD, be sure to read the rest of this article.
Clinical experience1: Benefits of OMAD
Clinicians who are experienced in prescribing low-carb diets and intermittent fasting often use OMAD to aid with weight loss stalls. Temporary use of OMAD is a good option for patients who are not losing weight due to low-carb diets. Our evidence-based guide provides more information on how to address weight loss stalls.
People who follow an OMAD diet do so because it is easy to prepare food and eat only once a day. This is especially useful for people who frequently travel, work shifts, or have busy schedules.
Consider how much time it takes to plan, shop for, and prepare meals. We haven’t even touched on the dirty dishes. How much time can you save if you only eat three meals a day?
OMAD is a combination of intermittent fasting and time-restricted eating. It may be used to reduce hyperinsulinemia, diabetes, and metabolic syndrome. OMAD can deliver better results when used correctly.
Some people see OMAD a “easy” way of reducing calorie intake. It is physically hard to exceed your daily calories if you limit the amount of food you allow yourself to consume in a 30- to 60-minute window. Although it’s possible (just ask Joey Chestnut who can consume more than 10,000 calories in a matter of minutes), it is not easy. OMAD is a strategy that can work best for those who have a strict schedule and don’t want to snack. (Of course “easy” depends on the person who is looking.
Concerns regarding OMAD
Disordered eating can be caused by eating patterns that encourage food restriction and then more food intake. If you have an eating disorder history, you should avoid OMAD.
Chronic caloric restriction
One of the many clinical benefits of OMAD is its ability to create an environment that naturally lowers your caloric intake. However, OMAD can make it difficult to get adequate calories if you are eating it long-term without interruptions. OMAD may then look a lot more like chronic caloric restrictions. While chronic caloric restriction can help with weight loss initially, it can also lead to long-term problems. It tends to lower the resting metabolic rate which makes it very difficult to maintain weight loss.
Inadequate protein intake
OMAD can lead to protein restrictions, just as it promotes caloric restriction. Protein is important for feeling full and satisfied. It may not matter if you can eat 16-oz ribeye and a few fried eggs in one go. If that seems like too much, your daily OMAD may not be sufficient.
Intake of too many carbs
We recommend limiting your net carb intake to 20 grams per day if you want to stay ketosis-compliant. We recommend that you limit your daily carb intake to no more than 20 grams. You can eat one meal with OMAD. This means you could theoretically consume all 20 grams of carbs in one go. This is compatible with a ketogenic diet. However, people who are insulin-resistant may find it difficult to digest 20 grams of carbs. They will experience a spike in glucose and insulin which ultimately leads to a decrease or elimination in ketone levels.
Diarrhea and GI upset
Many people find that a consistent cycle of eating little food and eating a lot of food can cause abdominal discomfort, even diarrhea. It’s difficult to know how many OMAD sufferers experience this but our panel of clinical experts considers it rare, but not uncommon.
Take medication with food
The OMAD is a major hurdle for those who have to take prescription medication with food more often than once per day. Talk to your healthcare provider if you have other options. If you are not sure, OMAD may not be safe for your health.
For some people, it is difficult to fast while exercising. You might find it difficult to follow an OMAD plan if you are active. We encourage you to try fasted exercise. Clinical experience and research suggest that fasted exercise can be safe and effective in weight loss.
People can thrive and do well with intermittent fasting and time-restricted eating. Some people are more vulnerable to side effects. You can expect to feel hungry and low in energy. OMAD and intermittent fasting can cause severe side effects such as feeling very tired, dizzy, nauseated or unwell. If you have any of these side effects, OMAD may not be the right choice. Talk to your doctor about whether any modifications (such as shorter fasting periods or greater adaptation to fat loss through reduction in dietary carbs) might be possible.
What does science tell us?
There is a growing body of literature on intermittent fasting and time-restricted eats. Different protocols are being investigated in different studies.
One study found that eating a restricted diet of 14:10 can lead to weight loss and improved metabolic health.7 But how do we find out if this is true for OMAD? Is 23:1 more effective than 14:10? It could be. It makes sense that lowering insulin levels and mobilizing stored fat for 14 hours can be beneficial. However, 23 hours could prove to be more beneficial. This assumes that longer periods of time don’t have any negative counterbalancing effects.
While some studies have shown a net benefit to longer fasting periods, others do not capture OMAD eating. A pilot study found that obese patients with diabetes experienced a decrease in fasting and postprandial glucose levels after eating for two weeks within a seven-hour window (17 hours).
A 2009 crossover study that was closer to the standard OMAD found that eating three meals per day was more beneficial than eating the same food in a 20 to 4 window.9 It consisted of 15% protein, 35% fat, and 50% carbohydrates. Comparing the 1 meal/day and 3 meals/day groups, the body fat was 4.4 lbs (2 kg) lower, while the lean mass was the exact same. The 3 meals/day group didn’t lose any weight. The study also showed that the fasters had lower levels of triglycerides (93 mg/dL vs. 102 mg/dL), HDL (62 mg/dL vs. 57 mg/dL) and LDL (136 mg/dL vs. 113 mg/dL) immediately after the time-restricted portion.
The authors did warn about higher LDL levels. However, a closer look revealed that the ratio of total cholesterol to HDL remained the same at 3.5 for time-restricted versus 3.4 for three meals per day. While the ratio of TG:HDL was slightly lower in the time-restricted group (1.5 vs. 1.8). While we cannot definitively say that higher LDL is not a concern, evidence suggests that higher HDL and lower triglycerides could predict lower cardiovascular risk even when there is high LDL.
It seems reasonable to extrapolate these results to OMAD and expect similar benefits, at least for the short-term. We don’t know whether the benefits will persist with daily, long-term OMAD. We are hesitant to recommend daily OMAD due to this uncertainty and lack of long-term data. Alternate-day fasting is an appealing option.
Alternative-day fasting seems to alleviate concerns about chronic caloric restriction. Every other day is marked by normal eating with very few or no fasting days. ADF was compared to daily caloric restriction in a short-term study and showed similar results for body composition and weight loss. However, ADF had a lower adjusted resting metabolic rate.
Although neither these studies have shown that alternate day fasting can be sustained over long periods of time, they do suggest that OMAD can still be used in a healthy, sustainable eating plan.
“Best use” of OMAD
OMAD seems to be a powerful tool for weight loss and improving metabolic health. We caution against the use of OMAD daily for long periods due to all the above reasons. For those with more restricted eating habits, OMAD could be used up to three times per week on non-consecutive day. This protocol is not science-based and has a lot of high-quality evidence. Instead, it is based on clinical experience and existing evidence.
Remember that OMAD does not give you the right to eat what you like. It doesn’t matter what you eat for one meal. It is important to follow your low-carb diet on both OMAD and non OMAD days. Clinical experience shows that a low-carb diet can make intermittent fasting and OMAD more manageable by reducing hunger pangs and cravings.
Here’s a sample week using OMAD:14
* Monday: Eat two meals, with 16:8 restriction on eating. The goal is 1,800 calories.
* Tuesday: OMAD, approximately 1,200 calories (assuming a 1,800-calorie standard). 30 grams protein (105g), 10g carbs, and 85g fat are the goals. This volume may be too much for some people. Consider extending your eating time so you can eat “snacks” of nuts and cheese, and then, one hour later, your entire meal.
* Wednesday: Eat two meals, 16:8 restriction on eating, 1,800 calories
* Thursday: OMAD is similar to Tuesday
* Friday: Eat two meals, 16:8 time-restricted, 1,800 calories
* Saturday: You can eat as you like, just keep your low-carb diet in place!
* Sunday: OMAD is similar to Tuesday
Is OMAD a good and healthy tool to help you lose weight and improve your metabolic health? It can. However, it is important to use it sensibly and to pay attention your nutrient and calorie needs.
You may be able to incorporate it into a healthy eating pattern that is time-restricted and low in carbs, and you will likely reach your weight and health goals.