The One Meal a Day (OMAD) diet can help you lose weight, but its downsides make it a poor fit for most people. It’s a super strict form of intermittent fasting where you eat all your daily calories in one meal and fast for the other 23 hours.
How One Meal a Day Affects Weight Loss
OMAD is one of the tools for creating a calorie deficit, but it’s not a better one. A large study published in The New England Journal of Medicine compared people who followed time-restricted eating with those who followed standard calorie restriction for one year. The two groups lost almost the same amount of weight. Changes in waist size, body fat, blood pressure, and metabolic risk factors were also similar between groups.
So, OMAD can help you lose weight, but eating fewer calories across three meals a day is a healthier plan. OMAD can also make it harder to keep your muscles strong, get all the nutrients your body needs, and keep your blood sugar steady.
How It Works
Like other forms of intermittent fasting, OMAD is a way of manipulating how your body finds and uses fuel. When you eat in a more traditional pattern, your energy comes from the food you eat.
When you take in carbohydrates, your body breaks them down into sugars. If you have more sugar in your blood than you need, a chemical called insulin carries the extra into your fat cells. When you don’t eat for long periods of time, your body makes less insulin. Your cells still need energy for fuel, so your fat cells release energy. But for this to happen, you need to fast long enough for your insulin levels to drop.
The Pros
The OMAD diet may help you lose body fat or reach your weight loss goals. That’s if you don’t have a health condition that makes it risky.
It may help you burn fat. One study found eating one meal a day may lower your total body fat.
You might feel more alert. When you fast during daylight hours, your body releases more of a chemical called orexin-A, which makes you feel more alert. This isn’t specific to OMAD, and it doesn’t apply if you ate your single meal in the morning.
Eating in the morning and fasting overnight may help you lose weight. The OMAD diet doesn’t tell you which meal to eat. That said, people who fast overnight and eat a larger meal in the morning tend to lose more weight than those who eat at dinnertime.
The Cons
This diet is strict, and it can be unhealthy for many people. Some other downsides are:
It can be hard to stick with. Eating plans like OMAD have a dropout rate of up to 65%. It’s not easier to follow than other diets that simply cut calories.
It may make you hungrier. When you eat one meal a day rather than three, your body produces more of a hormone called ghrelin, which makes you feel hungry.
It’s not more effective than calorie reduction. Even if the OMAD diet makes you feel hungrier, it’s unlikely to lead to more weight loss than simply eating fewer calories during the day.
Who Should Avoid Eating One Meal a Day?
OMAD can cause or worsen a range of health issues. Talk to your doctor about its risks before deciding to try it. They can help you find healthier plans for losing weight.
Safety Concerns
Eating only one meal a day may cause serious health risks for many people, including those with issues such as cardiovascular disease, diabetes, and a history of eating disorders.
Eating one meal a day can increase your blood pressure and cholesterol. This occurred in a group of healthy adults who switched to one meal a day to participate in a study. If you already have concerns in either area, eating just once a day might not be safe.
Eating one meal late can cause your blood sugar to spike. Some OMAD studies have asked people to eat their single meal between 4 p.m. and 8 p.m. These participants had morning blood sugar levels that were higher than normal, and their bodies were less able to deal with this extra sugar.
Fasting can cause blood sugar crashes. Fasting of any type raises the risk of extremely low blood sugar, also known as hypoglycemia, in people who have type 2 diabetes.
Every weight-loss plan affects people differently. Talk to your doctor before trying OMAD to make sure it is safe and right for you.
Takeaways
OMAD is a super strict form of intermittent fasting, as it requires 23 hours of fasting every day. While it can lead to weight loss, research shows its results aren’t better than a typical calorie-limiting diet consumed throughout the day. It can come with health risks for many people, including those with diabetes or those who are pregnant, so it’s not a good choice for many people. Talk to your doctor before trying it.
FAQs About the OMAD Diet
Is black coffee, tea, or bone broth allowed during fasting hours with OMAD?
Zero-calorie, unsweetened drinks, such as water, black coffee, or plain tea, are all that’s allowed outside the one-hour eating window in the OMAD diet.
How can I get enough calories and nutrients in a one-hour eating window?
Follow the OMAD macro guidelines for a balanced meal. They include getting 0.7–1.0 grams of protein per pound of body weight from foods such as grilled chicken or salmon, about 35% of your remaining daily calories from healthy fats like avocados and olive oil, and the rest from fiber-rich complex carbohydrates such as sweet potatoes and quinoa.
How should I schedule workouts while eating only one meal a day?
The best timing for you depends on your energy level and other variables. But some experts suggest scheduling your workouts 1-2 hours before your single meal. Also make sure to drink enough water.
How do I take prescription medications or vitamins that require food?
If you need food with medications you take more than once a day, OMAD is not a good choice for you.
