Could you make it a habit to only eat once a day? And should you?

In recent years, intermittent fasting diets, in which you limit your eating window by extending your overnight fast, have become increasingly popular as a way to lose weight and potentially improve health.

The OMAD diet, which stands for the One Meal A Day Diet, is essentially an extreme version of a time-limited intermittent fasting diet. Although many people are interested in the OMAD diet in hopes of losing weight and improving health, there are also potential downsides to OMAD.

To learn more about the pros and cons of the OMAD diet and tips for adhering to the OMAD diet, we spoke to Kimberly Gomer, MS, RD/LDN, a Registered Dietitian and Nutrition Director Body Beautiful Miami.

What is the OMAD diet?

The OMAD diet, short for One Meal A Day diet, consists of eating just one meal a day. Basically, it’s about fasting for 23 hours and maintaining an eating window of about an hour.

Gormer says the OMAD diet isn’t really a “diet” in the traditional sense of the word, since a diet involves an eating plan or specific foods that you can and cannot eat.

“Instead of this, [the OMAD diet] is specifically geared towards meal timing—in this case, one meal a day,” says Gormer. “In its strictest application, people are supposed to eat zero calories (considering water, black coffee, or tea) apart from the one meal they are allowed to eat for the day.”

Is OMAD good for losing weight? What are some other benefits?

Gormer says that while most people turn to the OMAD diet as a way to manage weight, there are other potential benefits as well.

“The benefit for those trying to normalize insulin response, lower blood sugar and/or lose weight is that it allows the body to go on metabolic pause. If there are no calories, there is no insulin response,” she says.

Gormer goes on to explain that after eating (and especially after eating carbohydrate-rich foods), blood sugar spikes as those nutrients are digested. That’s a good thing, because cells need glucose for energy, but they can’t absorb it from the bloodstream without insulin. Insulin is a hormone produced and secreted by the pancreas in response to an increase in blood sugar.

“Insulin acts like a key that opens a gate and allows the cells to take in the sugar and then releases the rest of the sugar for later use, ie energy or fat storage in fat cells, the fat cells,” explains Gormer. “When people are insulin resistant, that key becomes sticky and the cells don’t get the sugar. The body senses a problem and calls for more insulin.”

However, insulin can increase hunger. The more insulin circulating in your body at any given time, the more likely you are to have an insatiable appetite.

“In the United States, an estimated 60 to 70 million people have insulin resistance, hence the idea of ​​limiting the timing and amount of insulin secretion [via the OMAD diet] is useful for blood sugar response and weight loss,” notes Gormer.

Gormer says that because of its one-meal-a-day nature, the OMAD diet reduces your body’s exposure to insulin and the frequency of insulin secretion, which in turn can reduce appetite and potentially improve insulin sensitivity.

Therefore, the OMAD diet has two effects on weight loss: Eating one meal a day not only reduces calorie intake by default since you are not grazing or consuming calories for several hours, but it can also help control appetite, by decreasing insulin levels.

What side effects can OMAD have?

According to Gormer, the main disadvantages of the OMAD diet are that it can potentially lead to binge eating or overeating and that it can be difficult to meet all of your nutritional needs.

Because people wait all day to eat and only have one opportunity to enjoy food, this can psychologically trigger some to want to eat as much food as possible, often at the expense of wise food choices. This can lead to nutritional deficiencies and may not produce the weight loss results you hope for, depending on how many calories you end up consuming and where they are coming from.

Additionally, the OMAD diet is not typically recommended for athletes or people who exercise vigorously or for prolonged workouts, as it is typically not possible to adequately fuel your body before or after exercise.

Ultimately, Gormer says the OMAD is overly restrictive overall and isn’t a sound approach to healthy eating in general.

“I believe that while there will be weight loss if the person follows the protocol, at some point due to the extreme restriction, it will lead to overeating. The risk of the diet is that a person once again has high hopes for weight loss from this extreme plan [is] disappointed when they cut down, lose some weight and then put it all back on,” she warns. “Calorie restriction occurs when only one meal a day is eaten, but often junk food is craved as the body tries to avoid this extreme restriction.”

In addition, Gormer believed that the OMAD diet was not optimal for health, as it does not usually lead to permanent weight loss and can even lead to metabolic damage with prolonged use.

“Repeated calorie restriction causes BMR (basic metabolic rate) to slow, making it increasingly difficult to lose weight the more restrictive the diets one follows. Because of this, diets can work initially, but after a while they don’t seem to work,” she says. “For example, the BMR may be 2,000 [calories per day], but if that person diets, quickly gains weight, regains weight, and more, on the next diet, their BMR has slowed down due to the restriction from their last diet, so their BMR is now 1,800 calories. This cycle repeats itself to the point where people can’t lose weight no matter how much they limit themselves.”

Finally, another disadvantage of the OMAD diet is that the infrequent food makes you feel very hungry and low on energy for most of the day.

What do you eat on OMAD?

When following the OMAD diet, it’s important to eat nutritious, filling foods like whole, unprocessed vegetables, lean proteins, healthy fats like nuts and seeds, and some whole grains and fruits.

Is OMAD Fasting Healthy?

Gormer strongly encourages people to seek healthier alternatives to the OMAD diet.

“The best thing for health is to avoid processed foods, including packaged foods loaded with sugar, processed grains, and highly processed vegetable seed oils (soybean, corn, canola, rice bran, sunflower, safflower, and vegetables). Instead, stick to whole foods like protein, vegetables, healthy fats (like avocado and olive oil), and limited carbohydrates (whole fruits and grains), depending on your lifestyle, exercise habits, and individual metabolism,” advises Gormer. “Avoiding fad diets, fasting, and too much restriction to avoid metabolic damage is key.”

In terms of timing and frequency of eating, Gormer suggests limiting snacking and only eating three meals a day if you’re tackling something like the OMAD diet for insulin reasons. Finally, she suggests working with a Registered Dietitian and a Nutritionist who can support you with your diet and health goals and create a customized nutrition plan that makes sense for your body and life.

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