One Meal a Day (OMAD): A Critical Look at the Diet Trend

The OMAD diet, a type of intermittent fasting, involves consuming all daily calories within a one-hour window. While it may lead to weight loss due to calorie restriction, potential downsides include nutrient deficiencies, increased hunger, and negative metabolic effects.
Written by
Katherine Magsanoc
Published on
June 10, 2025
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The following article is based on information from the Healthline article found at this link: https://www.healthline.com/health/one-meal-a-day. All information presented here is derived from that source and should not be considered medical advice. Consult a healthcare professional before making any significant dietary changes.

The one-meal-a-day (OMAD) diet, a form of intermittent fasting, has gained popularity as a weight-loss strategy. This approach restricts calorie intake to a single meal within a short timeframe, typically lasting an hour or so.

While proponents claim various health benefits, a balanced assessment reveals both potential advantages and significant drawbacks.

Weight Loss Potential and Mechanisms

OMAD’s primary appeal lies in its potential for weight loss. By drastically reducing daily caloric intake, it creates a calorie deficit, leading to fat loss.

Studies, such as a 2022 study on lean adults, show that concentrating calorie intake into a short evening window can result in greater weight loss than consuming three meals throughout the day. A 2017 review also indicated that intermittent fasting, including OMAD, can promote weight loss, although not necessarily more effectively than traditional calorie restriction.

However, it’s crucial to note that this weight loss may also include lean body mass, potentially increasing the risk of metabolic diseases.

Potential Benefits Beyond Weight Loss

Research links fasting, in general, to several potential health benefits. These include reduced blood sugar levels, improvements in certain heart disease risk factors (like LDL cholesterol), and reduced inflammation.

Animal studies even suggest potential neuroprotective effects.

However, it is crucial to emphasize that these benefits are associated with fasting in general, not specifically with the extreme OMAD approach. In fact, some research suggests OMAD might have more adverse effects than less restrictive fasting methods.

Significant Downsides and Risks

The extreme nature of OMAD presents several potential downsides. Studies indicate that severe calorie restriction can negatively impact health, possibly raising cholesterol levels and blood pressure.

Other research suggests that OMAD may increase fasting blood sugar levels, impair insulin response, and elevate ghrelin (an appetite-stimulating hormone).

The diet can also lead to extreme hunger, dizziness, nausea, irritability, low energy, and constipation.

OMAD is unsuitable for many groups, including pregnant or breastfeeding individuals, children and adolescents, older adults, and those with eating disorders. The risk of nutrient deficiencies is also high, as it’s difficult to consume all necessary nutrients in a single meal.

Furthermore, individuals may compensate by consuming highly processed, calorie-dense foods during their eating window, negating any potential health benefits.

A concerning 2022 study even linked OMAD to an increased risk of all-cause and cardiovascular disease mortality.

Food Choices and Considerations

If choosing to follow OMAD (though generally discouraged by healthcare professionals), it’s essential to prioritize nutrient-dense foods such as fruits, vegetables, whole grains, lean proteins, and healthy fats. Highly processed foods should be minimized.

Even with careful planning, meeting daily caloric and nutrient requirements within a single meal can be challenging.

While intermittent fasting, in more moderate forms, may offer some health advantages, OMAD presents significant risks and is generally not recommended.

The potential benefits are often outweighed by the risks of nutrient deficiencies, negative metabolic effects, and the difficulty in maintaining the diet long-term.

More sustainable approaches, like the 16/8 method or simply adopting a healthy, lower-calorie diet, are likely to provide better overall health outcomes.

Always consult a healthcare professional before undertaking any extreme dietary changes.

DISCLAIMER

This article provides general information and does not constitute medical advice. Consult your healthcare provider for personalized recommendations. If symptoms persist, consult your doctor.

Photo by Davey Gravy on Unsplash

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