The One Meal a Day, or OMAD, diet – is the latest weight-loss trend sweeping the nation. You may have seen it mentioned in news headlines or popping up on your social feeds. But what, exactly, is the OMAD diet – and is it safe? Let’s take a look at what this diet involves, the benefits it may offer and what you should know if you decide to give it a try.
What is the OMAD diet?
As its name suggests, the OMAD ("one meal a day") diet involves eating a single meal every day.
With the rise in popularity of
intermittent fasting, increased interest in OMAD isn’t too surprising. People who are already fasting for 12 to 16 hours a day might find it easy to naturally transition to eating just once a day.
The OMAD diet essentially involves a 22 or 23 hour fast, with a one or two hour allowed ‘eating window.’ Timing of that window may vary by person, but most people seem to prefer eating during traditional dinnertime hours.
What are some OMAD diet benefits?
Those who follow the OMAD diet typically do so to lose weight and improve their health. For many, it’s an easy way to cut calories and increase fat burn.
When you’re in a fasted state, your body uses fat stores for energy. So when your eating window is only one or two hours, you’re in fat-burning mode for 22 or more hours a day.
Depending on your specific calorie needs, many people are able to reach their calorie goals by eating just one meal. (It’s not difficult to eat 1,000 calories in a single meal; however, if a greater amount of calories is needed, say 2,500 to 3,000 a day, it can be difficult to eat that much at once.)
So is the OMAD diet safe, and does it actually work for weight loss? Let’s take a look at what the science says.
Most research on OMAD generally has been done for short periods of time from a few weeks to two months. These studies show
no long-term negative outcomes of eating only once a day. And those who self-report following the OMAD diet seem to tolerate it fine.
Studies show that eating once a day can lead to improved body composition. People following this eating pattern
reduced their fat mass and were able to maintain or gain lean muscle mass.
Research also shows people following the OMAD diet have
increased metabolic flexibility. This means that they can easily switch from running off carbs to burning fat for fuel.
“OMAD is one of many tools that can be used to support weight loss and/or general metabolic health,” says Alyssa Gallagher, registered dietitian and certified diabetes care and education specialist.
“It promotes insulin sensitivity, is a natural calorie restriction, and can jump start weight loss or improvement in insulin resistance in some people.”
Gallagher notes that she does not consider the OMAD diet ideal in the long term, however, as it can be difficult to sustain, especially in terms of meeting the body’s nutritional requirements, including getting enough protein.
Pros and cons of the OMAD Diet
Pros to note
Weight loss
The main reason people follow the OMAD diet is to lose weight. If you’re only eating once a day, you’ll likely be in a calorie deficit. Let’s say you need to eat 2,500 calories a day to maintain your weight. You start following OMAD and your caloric intake drops to around 1,500 to 1,800 calories a day. At this calorie level, you will start to lose weight.
Decreased hunger
Not everyone experiences decreased hunger levels on the OMAD diet, but some people do.
At first, you may feel really hungry, especially if you’re going from three regular meals a day down to just one. To ward off hunger pains, it’s recommended that you ease into the diet. Start by fasting 12-16 hours for a few weeks, then gradually work up to 22-23 hours. This way, your body won’t be as ‘shocked’ when you do eat only one meal.
When you’re fasting, your body is burning its own fat stores for fuel. The better your body is able to utilize fat for fuel, the less likely you are to be hungry. Put simply: you won’t be hungry because your body is using fat stores for energy, rather than triggering hunger so that you eat (for fuel).
Improved energy
Being in a state of
ketosis – burning fat for fuel – can improve energy levels. In fact, many people report better energy and even loss of the dreaded ‘afternoon slump.’
When you’re eating three meals a day, your body is trained to rely on those meals for fuel rather than tap into your fat stores. So every time you eat, you get an energy boost – and then you crash. It’s like being on a rollercoaster all day long. You eat; blood sugars spike. Insulin brings them back down, but then you need more glucose for fuel – and you’re hungry again.
You’re on a roller coaster all day long, every time you eat. When you eat, you’re blood sugars spike. Insulin then brings your blood sugars back down but then you need more glucose for fuel and you get hungry again. Eating all throughout the day never gives your body a chance to switch to fat-burning mode.
Because you have a supply of stored fat, your body will be running on your fat stores
Convenience
One of the main benefits of the OMAD diet is that you only need to shop for and prepare one meal a day. This can make
meal planning easy. Plus, you’ll save money!
Cons to consider
Difficult to build muscle
One of the biggest downsides of OMAD is that it’s difficult to eat enough
protein. Protein is the building block for lean muscle mass, and maintaining lean muscle mass is key to weight loss and longevity.
The body can best utilize 25 to 55 grams of protein at once for building muscle. If you’re only eating once a day, that’s only one opportunity to build muscle. If you’re eating protein three times a day, that gives your body
three opportunities to build muscle. Long term, OMAD is not the best diet for optimizing lean muscle mass.
Increased hunger
The majority of people who follow the OMAD diet experience increased hunger. It takes some mindset work and self-discipline to eat only once a day, especially when first starting out. Many people find that the intense feelings of hunger aren’t worth continuing with the diet long term.
A lot of food at once
No matter what diet you’re on, you need to meet your body’s basic nutrition needs. On the OMAD diet, you’ve got to do this with one meal. And that can mean the meal is
big.
As a dietitian, I recommend consuming 100 grams of protein a day. That’s the equivalent of about 14 ounces of chicken breast. That’s a lot of protein to eat at once! You may find that while yes, you’re losing weight on OMAD, you might be losing muscle as well.
Tips for trying the OMAD diet
If you’re interested in trying OMAD, consider the following advice for success:
Ease into it. While this is a good strategy with most diets, it’s especially helpful with OMAD. Cutting yourself off to just one meal a day can feel drastic and may immediately turn you off of the diet. Instead, ease in. Try OMAD for few days a week to start. (Remember, you don’t have to do OMAD every single day to reap the benefits of fasting. You might do it once or twice a week and find that it works great for you.)
If you’re a fasting pro, OMAD might be a natural transition for you. But if you’re completely new to fasting, you might consider beginning with shorter fasts of 12 hours, and then working your way up to 23 hours.
It can be helpful to
track your calorie intake to ensure you’re meeting your body’s basic nutrition needs. Even when you’re trying to lose weight and are in a calorie deficit, you don’t want to reduce your calorie intake too low long term. This could put you at risk for nutrition deficiencies.
Consider experimenting with your ‘eating window’ to determine what time of day is best for you. Try eating your daily meal at lunchtime, early afternoon and then evening. Which feels the best? You might
The bottom line
If you try OMAD and decide that it’s not for you, that’s OK! While this diet works great for some, most people find it very difficult to stick with over time.
When it comes to nutrition and fasting, we’re all different. There isn’t a one-size-fits-all approach. Take time to experiment with fasting and work up to OMAD to see if it’s something you can maintain or maybe just incorporate occasionally.
Remember: it’s important to consult with your healthcare provider before starting the OMAD diet or doing any type of fasting, especially if you take diabetic medications that could cause your blood sugar levels to drop too low (hypoglycemia).
While there are many approaches to fasting, and OMAD has been shown to improve some health markers, eating only one meal a day may not be sustainable for everyone. The biggest factor for weight loss and improving health is creating sustainable habits.
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