One Meal A Day

However, there is little evidence to support the notion that the one-meal-a-day can aid weight loss.

Is Eating One Meal a Day Safe?

The “One Meal a Day” diet, or OMAD diet, claims to help you lose weight by forcing your body to burn fat. It’s a type of intermittent fasting, which alternates between periods throughout the day in which you can eat anything and periods in which you don’t eat at all.

OMAD is particularly strict because you don’t eat for 23 hours, then consume all of your calories in a single meal.

Is Eating One Meal a Day a Safe and Effective Way to Lose Weight?

Eating one meal a day is a practice that many people swear by to lose weight and improve overall health. The one-meal-per-day diet is also referred to as OMAD.

Although the content and timing of the meal will vary based on personal preference, people following an OMAD diet typically restrict their calorie intake to a single meal or a short window of time.

The potential health benefits of OMAD are primarily related to fasting — restricting calorie intake during a set time period — and calorie restriction in general.

There are many types of intermittent fasting practices and multiple ways to implement OMAD.

Examples include having just one meal and fasting for the rest of the day or having one meal and eating limited amounts of food during fasting periods.

This type of diet creates a calorie deficit, which can lead to weight loss.

Other health benefits related to fasting include the potential to reduce heart disease risk factors, decrease blood sugar, and reduce inflammation ( 1 ).

However, compared to other fasting regimens, such as the 16/8 method, which involves 8-hour eating windows and 16-hour fasting windows, eating just one meal per day is one of the most extreme methods of intermittent fasting.

A few popular diets encourage eating one meal per day. For example, when following the Warrior Diet, a person eats a single meal a day, cycling between long periods of fasting with short periods of energy consumption.

Most people following OMAD choose to only consume dinner, although others choose breakfast or lunch as their one meal. Some versions of this eating pattern allow a snack or two in addition to the one meal.

However, some OMAD enthusiasts don’t consume anything containing calories during their fasting window and only consume calories during their chosen meal, which typically lasts an hour or so.

In order to lose weight, you must create an energy deficit.

You can do this by either increasing the number of calories you burn or reducing your calorie intake. Calorie restriction, no matter how you achieve it, will lead to fat loss.

People using the OMAD method are likely to lose weight simply because they’re taking in fewer overall calories than they normally would during a regular pattern of eating.

For example, a study in healthy adults found that restricting calorie intake to a 4-hour time period in the evening led to significantly greater body fat loss than when eating three separate meals throughout the day ( 2 ).

Research has also shown that intermittent fasting, including extended fasting periods like OMAD, is likely to result in weight loss.

However, it doesn’t seem to be any more effective than traditional methods of calorie restriction, such as reducing calorie intake at each meal ( 3 ).

An analysis that included 50,660 people showed that those who consumed 1 or 2 meals per day had a yearly reduction in body mass index (BMI) compared to those who consumed 3 meals per day.

The study also showed that an overnight fast of 18 or more hours was associated with decreased body weight, compared to shorter fasting windows ( 4 ).

However, these weight loss benefits are related to intermittent fasting in general, and not just the OMAD.

Plus, extreme methods of fasting, such as OMAD, may have side effects that people need to consider, such as increased hunger and problematic metabolic changes ( 5 ).

In addition to weight loss, research has linked fasting to a number of other health benefits. For example, fasting may help reduce blood sugar and certain heart disease risk factors, including LDL “bad” cholesterol ( 6 , 7 ).

Fasting has also been associated with reduction in markers of inflammation, including C-reactive protein ( 6 ).

Additionally, fasting may offer unique benefits for the health of the nervous system. It may slow neurodegeneration and promote longevity, according to animal research ( 8 , 9 ).

However, although these potential benefits are promising, it’s important to note that these benefits are associated with fasting in general and not OMAD specifically.

In fact, some research shows that the OMAD pattern may be more detrimental to health than other, less restrictive fasting methods ( 2 , 10 , 11 ).

Although research has associated fasting and calorie restriction with a variety of health benefits, some evidence suggests that restricting too much — which can include only consuming one meal a day — may do more harm than good.

For example, studies suggest that this extreme restriction may lead to increased total and LDL “bad” cholesterol and higher blood pressure levels compared to normal eating patterns or less extreme fasting methods ( 2 ).

Other studies have shown that eating one meal per day may increase fasting blood sugar levels, delay the body’s response to insulin, and increase levels of the appetite-stimulating hormone ghrelin, compared to eating 3 meals per day.

This can lead to extreme hunger ( 10 ).

What’s more, restricting calories to one meal a day may increase the chances of hypoglycemia, or low blood sugar, especially in those with type 2 diabetes ( 11 ).

In addition to these potential adverse effects, eating one meal a day can lead to symptoms including ( 12 ):

The OMAD diet is also not appropriate for many groups of people, including those who are pregnant or breastfeeding, children and teens, older adults, and people with eating disorders.

Limiting intake to one meal per day can also lead to disordered eating tendencies, impact a person’s social life, and be extremely difficult for most people to stick to.

What’s more, it can be very difficult to take in enough nutrients in one meal. This can lead to nutrient deficiencies, which can negatively affect your health and can lead to serious risks.

Lastly, some people following the OMAD dietary pattern will binge on highly processed, calorie-dense foods, like fast food, pizza, doughnuts, and ice cream, during their one meal.

While these foods can fit into a balanced lifestyle, exclusively eating foods high in added sugar and other unhealthful ingredients will negatively affect your health in the long run.

Overall, although there are benefits related to fasting and calorie restriction, research has shown that consuming 2 or 3 meals per day is likely a better option for overall health than eating one meal a day ( 5 ).

No matter the type of dietary pattern you choose, your intake should mostly consist of whole, nutrient-dense foods.

Although most health professionals would not recommend eating only one meal a day, if you do choose this eating pattern, it’s essential to ensure that you’re consuming a variety of nutritious foods, including:

• fruits, such as berries, citrus fruits, and bananas
• vegetables, such as kale, broccoli, cauliflower, asparagus and peppers
• starchy vegetables and grains, such as sweet potatoes, butternut squash, oats, quinoa, and barley
• healthful fats, such as avocados, olive oil, and unsweetened coconut
• legumes, such as peas, chickpeas, lentils, and black beans
• seeds, nuts, and nut butters, such as cashews, macadamia nuts, almonds, and pumpkin seeds
• dairy and plant-based alternative products, unsweetened yogurt, coconut milk, and cashew milk
• protein sources, such as chicken, fish, tofu, and eggs

Limit highly processed foods, such as:

• fast food
• sugary baked goods
• white bread
• sugary cereals
• soda
• chips

These foods offer little nutritional value, and eating them too often can lead to weight gain and increased disease risk ( 13 ).

During fasting windows, the OMAD diet requires people to keep calorie intake to a minimum.

In the strict OMAD diet, this means complete restriction of calories. You can still enjoy water and other noncaloric beverages in fasting periods.

Others choose to eat low calorie, high protein snacks during the day, like:

Again, most healthcare providers do not recommend eating just one meal a day, as it can be detrimental to overall health.

If you’re considering trying this dietary pattern, consult a trusted healthcare provider for advice before you start.

Eating one meal a day is unlikely to give you the calories and nutrients your body needs to thrive unless carefully planned. Choosing to eat within a longer time period may help you increase your nutrient intake.

If you do choose to try out eating one meal a day, you probably shouldn’t do it 7 days a week.

Most people follow the OMAD pattern a few days a week, cycling it in with a normal dietary pattern or a less restrictive intermittent fasting regimen, like the 16/8 method.

If eating one meal a day, try to make meals as nutrient-dense as possible. These meals should deliver at least 1,200 calories, which can be difficult for some to ingest over a normal meal window.

If you struggle to take in enough calories in one meal, consider increasing your eating window by an hour or so and splitting your meal into two smaller meals. This can help you get enough nutrients and calories without becoming overly full.

Here are some nutritionally complete meal ideas that are likely to exceed 1,200 calories, as long as portion sizes are large enough:

• Baked chicken with mashed sweet potato topped with butter and roasted broccoli with olive oil, followed by full fat Greek yogurt topped with berries, nuts, seeds, and honey.
• Grilled salmon topped with guacamole, brown rice and black bean salad, and roasted plantains, followed by fruit served with nut butter, hemp seeds, and coconut flakes.
• Egg omelette with goat cheese, avocado, and grilled vegetables cooked in coconut oil, crispy baked potato wedges, followed by a side of fruit dipped in dark chocolate and whipped cream.

As you can see, each meal should account for all food groups and include:

In a day, eating 1,200 calories is a general minimum. Most adults need much more than that to maintain their weight.

Keep in mind that this way of eating is much more difficult for those following specific dietary patterns, like vegan diets or low fat diets, due to the number of calories that must fit into a single meal.

Overall, trying to cram all of your calorie needs into one meal is not necessary no matter what your health goal is. This dietary pattern is also not sustainable or practical for most people.

Eating one meal a day may be a popular way to lose weight, but it’s likely not a good idea for overall health.

Although fasting in general — including prolonged fasting — may benefit health in a number of ways, people can reach the same health benefits using much more sustainable methods.

More sustainable diets include 16/8 intermittent fasting or simply following a healthful, lower-calorie diet if you’re currently eating in a surplus and want to promote weight loss.

Most healthcare providers advise against OMAD dietary patterns due to their extreme nature.

People can encourage better overall health through more sustainable methods.

Last medically reviewed on July 1, 2020

Q:

How long is it safe to eat just one meal per day, and might there be long-term bad effects if a person carries on with it for too long?

Although fasting can be a powerful tool in a person’s health toolbox, most health professionals do not support the one-meal-a-day diet as a long-term strategy. There is not yet enough research to confirm how long it is “safe” for, or any of the possible negative effects, though rebound weight gain, increased hunger, and nutritional inadequacy are some top concerns.

Natalie Butler, R.D., L.D. Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

Last medically reviewed on January 20, 2020

• Nutrition / Diet
• Obesity / Weight Loss / Fitness