One Meal a Day Diet: Medical Expert Analysis of Extreme Weight Loss Risks and Benefits

Based on my clinical experience and current medical research, I want to share important insights about the one meal a day diet following recent news of Korean singer Lee Jae-hoon's dramatic 10-kilogram weight loss in just three weeks. As a physician who has treated thousands of patients struggling with weight management over my 15 years of practice, I've witnessed both the remarkable short-term results and concerning long-term consequences of extreme intermittent fasting approaches like the OMAD diet.

The recent case of the 50-year-old Cool member highlights a growing trend toward extreme weight loss methods that promise rapid results. While his transformation appears impressive, the medical implications of such drastic dietary restrictions require careful examination from both clinical and patient safety perspectives.

Understanding One Meal a Day Diet Mechanisms

The one meal a day diet represents an extreme form of intermittent fasting where individuals consume all their daily calories within a single meal, typically lasting one hour. From a physiological standpoint, this approach creates a 23-hour fasting window that dramatically alters metabolic processes and hormone regulation.

During extended fasting periods, the body undergoes several metabolic adaptations. Insulin levels drop significantly, promoting fat oxidation and ketone production. Growth hormone secretion increases, theoretically preserving muscle mass, while cellular autophagy processes activate to remove damaged proteins and organelles.

However, the extreme nature of this intermittent fasting approach creates unique challenges. The compressed eating window makes it nearly impossible to consume adequate nutrients, particularly for individuals with higher caloric needs or specific medical conditions requiring consistent medication timing.

Clinical Benefits and Short-Term Results

In my clinical practice, I've observed that the one meal a day diet can produce rapid initial weight loss, primarily through caloric restriction and water weight reduction. Patients typically experience 2-4 pounds of weight loss in the first week, with continued steady decline when the protocol is followed consistently.

The most significant benefit I observe is improved insulin sensitivity in patients with prediabetes or metabolic syndrome. Extended fasting periods allow insulin levels to normalize, potentially improving glucose metabolism and reducing inflammation markers. Several of my patients have shown improved HbA1c levels within three months of starting modified intermittent fasting protocols.

The psychological benefits cannot be overlooked. Many patients report feeling more in control of their eating habits and experiencing reduced food cravings after the initial adaptation period. This sense of dietary mastery can be particularly empowering for individuals who have struggled with portion control or emotional eating patterns.

Medical Risks and Long-Term Health Concerns

Despite potential short-term benefits, my clinical experience reveals significant concerns about extreme intermittent fasting approaches, particularly when followed for extended periods without medical supervision. The most pressing issue I encounter is nutritional deficiency development, even when patients believe they're eating balanced meals.

Consuming adequate protein, vitamins, minerals, and fiber within a single meal proves extremely challenging. Most adults require 0.8-1.2 grams of protein per kilogram of body weight daily, which becomes difficult to achieve alongside other essential nutrients in one sitting. This is particularly concerning for patients over 50, who face increased risk of sarcopenia.

The hormonal disruptions I observe in long-term OMAD practitioners are particularly concerning. Women frequently experience menstrual irregularities, while both men and women may develop thyroid function changes, cortisol dysregulation, and altered leptin sensitivity. These hormonal imbalances can persist even after returning to normal eating patterns.

Gallbladder complications represent another serious concern. Rapid weight loss and extended fasting periods increase gallstone formation risk, particularly in women and individuals with existing risk factors. I've treated several patients who developed acute cholecystitis while following extreme fasting protocols.

Safe Implementation Guidelines for Patients

For patients determined to try intermittent fasting approaches, I recommend a gradual, medically supervised transition rather than jumping directly into extreme protocols. The key is creating a sustainable approach that minimizes health risks while achieving reasonable weight loss goals.

If implementing any form of extended fasting, the single meal must be exceptionally well-planned to include all essential nutrients. I work with patients to ensure their meal contains high-quality protein sources, complex carbohydrates, healthy fats, and a variety of vegetables to maximize nutrient density.

Timing considerations are crucial for safety and effectiveness. I recommend scheduling the single meal during the evening to align with natural circadian rhythms and social eating patterns. This approach also helps prevent the afternoon energy crashes that commonly occur with morning or midday eating windows.

Medical Monitoring and Risk Assessment

Regular medical monitoring becomes absolutely essential for anyone following extreme intermittent fasting protocols. In my practice, I require monthly check-ins for the first three months, then quarterly assessments for ongoing OMAD practitioners. This intensive monitoring helps identify problems before they become serious health issues.

The laboratory tests I order include comprehensive metabolic panels, complete blood counts, thyroid function tests, vitamin B12 and folate levels, iron studies, and lipid profiles. I also monitor body composition using DEXA scans or bioelectrical impedance to track muscle mass changes alongside weight loss.

Warning signs that require immediate dietary modification include persistent fatigue, hair loss, menstrual irregularities, mood changes, difficulty concentrating, or any signs of eating disorder development. I've learned that early intervention prevents more serious complications and helps patients transition to sustainable long-term approaches.

For patients who experience positive results with careful monitoring, I emphasize that extreme intermittent fasting should be viewed as a short-term intervention rather than a permanent lifestyle. Most successful patients in my practice use OMAD for 3-6 months to achieve initial weight loss goals, then transition to more sustainable eating patterns for long-term maintenance.

Medical Summary: Balancing Rapid Results with Long-Term Health in One Meal a Day Dieting

After treating hundreds of patients interested in extreme intermittent fasting approaches, I've learned that the one meal a day diet can be an effective short-term weight loss tool when implemented with proper medical supervision and safety protocols. However, the risks often outweigh the benefits for most individuals, particularly when followed for extended periods.

The case of Lee Jae-hoon's rapid 10-kilogram weight loss illustrates both the potential and the dangers of extreme dietary restriction. While such dramatic results may seem appealing, the long-term health implications require careful consideration and professional guidance.

My recommendation for patients seeking significant weight loss is to explore less extreme intermittent fasting approaches first, such as 16:8 or 18:6 protocols, which can provide many of the same metabolic benefits with reduced risk of nutritional deficiencies and hormonal disruption. These approaches are more sustainable and allow for better social integration while still promoting effective weight management.

For those determined to try OMAD despite the risks, medical supervision is non-negotiable. Regular monitoring, gradual implementation, and a clear exit strategy help minimize potential complications while maximizing the chances of achieving sustainable results.