“This can be a safe diet if done correctly, and if you ensure you are getting adequate calories and nutrition when you’re eating,” says Shapiro. Overall, IF diets (including more extreme versions, like OMAD) are unlikely to cause harm to adults who are a healthy weight, overweight, or who have obesity, notes one review.
But OMAD is a restrictive eating approach that won’t necessarily appeal to everyone. If you’re following OMAD, you’ll need to take care not to overeat or overindulge on unhealthy foods during your main meal. You may also struggle to fit an entire day’s caloric intake into one large meal — or find yourself feeling uncomfortably full after eating this much in one sitting. There’s also a lack of research on the long-term effects of OMAD
Moreover, OMAD may actually be unsafe for certain groups of people. This includes people who are pregnant or nursing, who are younger than 18, and people who have an eating disorder or a history of disordered eating, says Moskovitz.
Another word of caution: If you take medication that must be consumed with food, reconsider OMAD. Not taking meds as prescribed could negatively affect absorbability and increase your risk of side effects, says Moskovitz. Examples of food-dependent medications include aspirin, certain NSAIDs, certain steroids, and allopurinol (Zyloprim).
Shapiro also advises that people living with diabetes who are taking insulin should not follow this diet, as OMAD can affect blood sugar levels. In general, people with diabetes need to eat balanced meals regularly throughout the day, adds Moskovitz. “Going prolonged periods of time without eating can lead to harmful blood sugar lows followed by subsequent highs once a larger meal is inevitably consumed,” she explains. “This pattern of inconsistent eating can make it difficult to keep blood sugar levels low and stable.”
Finally, if you often have gastrointestinal (GI) issues like bloating or an upset stomach, OMAD may not be a good fit for you. This diet requires you to eat a lot of food at one time, which may cause GI discomfort.
Still, many people who are not in these categories will decide to move ahead with OMAD — and if you’re one of these individuals, know that careful planning is key. “If you’re going to attempt it, you still have to make sure you’re doing your best to eat balanced and nutritious meals and that you’re still eating enough calories for the day if you want to stay healthy,” advises Moskovitz. “Fasting alone won’t be beneficial if [you’re] not carefully constructing the meals you’re eating in that time frame.”
Always speak to your doctor or an RDN before starting a new diet, especially if you’re managing an underlying health condition or taking medication, or if OMAD represents a dramatic change in the way you eat.
If you are interested in trying OMAD but have not yet tried other types of IF, start slowly, suggests Shapiro. “Start with a 12-hour fast and then build up to 14 or 16 hours. Then try OMAD for a few days once you have eased your body into it,” she explains.
FAQs
While experts agree that there are benefits to intermittent fasting, they also note the risks of the OMAD diet and fasting in general. The OMAD diet's severe restriction “may lead to disordered eating and make it extremely challenging to meet daily nutrient needs for vitamins, minerals and fiber,” cautions Dr.
Can OMAD cause health problems? ›
For most people, there are no serious dangers involved in eating one meal a day, other than the discomforts of feeling hungry. That said, there are some risks for people with cardiovascular disease or diabetes. Eating one meal a day can increase your blood pressure and cholesterol.
Is OMAD safe long term? ›
How long should you stay on the OMAD diet? Nutrition professionals do not advise trying the OMAD diet for any length of time. It's incredibly restrictive and unsustainable and can lead to extreme weight loss, nutrient deficiencies and binging.
What are the precautions for OMAD? ›
Some safety precautions:
- Don't adopt OMAD if you have type-1 diabetes, an eating disorder, or are already underweight. Pregnant women and nursing mothers should avoid OMAD as well. ...
- Stay hydrated while you fast. ...
- If you start to feel bad, eat! ...
- Doing an OMAD fast? ...
- Download the LIFE Fasting Tracker app here.
The one-meal-a-day diet (OMAD) — also known as 23:1 intermittent fasting — may help people lose weight and body fat. However, eating one meal a day can lead to hunger and cravings and may not be suitable for everyone. When following this diet, a person will eat only one meal a day.
Is OMAD risky? ›
While experts agree that there are benefits to intermittent fasting, they also note the risks of the OMAD diet and fasting in general. The OMAD diet's severe restriction “may lead to disordered eating and make it extremely challenging to meet daily nutrient needs for vitamins, minerals and fiber,” cautions Dr.
Is OMAD good for gut health? ›
Benefits of OMAD
OMAD is one of the best ways to improve gut health by allowing your digestive system time to rest and repair itself. Temporary calorie restrictions — such as those produced by OMAD — may directly reduce endotoxin levels, large amounts of which can cause a leaky gut.
Is OMAD everyday OK? ›
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.
Does OMAD slow down your metabolism? ›
Along with creating a calorie deficit, resulting in weight loss, advocates believe the OMAD diet's extended fasting period leads to physiological changes in the body that promote better health, including boosting your metabolism by triggering a process called ketosis, where your body burns stored fat for energy instead ...
What are the cons of long term fasting? ›
Of course, many people also fast safely, but it's worth noting that fasting isn't a risk-free experiment. Less serious drawbacks also include intense mood swings, low energy, and irritability. Fasting lowers blood pressure, so you may feel weak, dizzy, or nauseous during the fast.
The OMAD diet allows you to drink beverages during your 23-hour fast. Your beverages must be calorie-free, like black coffee or water, Dana Angelo White, RDN, a sports dietitian based in Connecticut and author of "Healthy Instant Pot Cookbook," told Health.
What is the one plate rule for OMAD? ›
You follow a 23:1 rule, where you fast for 23 hours and then have one hour of eating per day. Ideally, and for consistency, you eat within the same four-hour timeframe every day, only use one standard dinner plate (no seconds), and the food on your plate can't be more than three inches high.
Why am I not losing weight on OMAD? ›
If you've tried intermittent fasting but aren't losing weight, possible reasons why include overeating during your eating window and poor food choices. To help, you can try eating fewer calories, work on balancing your meals, or create a smaller or larger eating window.
Is OMAD sustainable long-term? ›
But it's the long-term sustainability — or lack thereof — of the OMAD diet that concerns nutrition experts. “While it can create a calorie deficit and result in weight loss, as a nutritionist, I don't think it's a sustainable way to live,” said Young.
Is OMAD better than intermittent fasting? ›
Although various forms of intermittent fasting have been shown to be an effective way to shed pounds, the OMAD diet is not recommended by nutritionists and can even be dangerous for people with certain health problems.
How long can you do OMAD? ›
Personally, I would not recommend it as a long-term way of eating for weeks or months at a time. However, one 2016 study links eating one or two meals a day to a reduction in BMI , and some people have great results turning OMAD into a lifelong commitment.
Is it bad to eat one unhealthy meal a day? ›
It's normal and acceptable to enjoy an indulgent meal from time to time, just don't make it a regular occurrence. Don't think of a bad meal as cheating, but rather as a “conscious indulgence.” As long as you follow a healthy diet 90 percent of the time, you can have a “conscious indulgence” two to three times a week.
Can OMAD cause digestive issues? ›
The Challenges of OMAD diets
Therefore, restricting meals to only once per day can be difficult. Following OMAD may cause digestive issues in some people. Consuming a very large meal once per day may cause bloating and digestive upset.
Does OMAD cause inflammation? ›
Helps lower inflammation
Research published in Cell found that fasting reduces the release and potency of monocytes, a type of pro-inflammatory immune cell. This explains why OMAD can help alleviate symptoms and improve overall well-being in individuals with chronic inflammatory health conditions.
