This week, a reader reached out with a question that many people find themselves asking after a period of intentional fasting. While participating in a church fast, they noticed a welcome sense of "lightness" and some initial weight loss, leading them to wonder: Is it healthy to eat only once a day as a lifelong plan? To understand whether this version of fasting is sustainable for the long haul, it is important to look past the initial weight loss and "lightness" and examine what the science says about how the body handles this routine over years, rather than just days or weeks.

My Response

The "One Meal a Day" (OMAD) approach is an extreme version of the intermittent fasting world. It is technically a 23:1 fasting protocol. Most research on intermittent fasting focuses on the 16:8 (which is observing16 hours of fasting and eating within an 8-hour window), or 18:6 (which is observing18 hours of fasting and eating within a 6-hour window). Direct long-term studies specifically focusing on the ‘one meal a day’ fasting approach are scarce. We can however extrapolate or infer from what we know about human biology.

What are the likely benefits of ‘one meal a day’?

The one meal a day fasting approach may trigger a deep "cellular cleanup" known as autophagy, which helps the body repair damaged cells and potentially slow down aging. Also, insulin levels are low since insulin is triggered in response to only one meal. By keeping insulin levels low for the majority of the day, the OMAD approach assists the body in managing blood sugar more effectively and can even help reverse insulin resistance. Furthermore, eating only once a day simplifies the daily routine by removing the mental stress of planning several meals, which reduces "decision fatigue" and helps individuals stay consistent with their health goals.

The Practical Challenges

Consuming all your daily nutrients in a single meal is practically challenging and nearly impossible. Overtime this could lead to significant micronutrient deficiencies and weakened bones. Additionally, because the body processes protein more efficiently when it is spread across multiple meals, relying on only one meal a day can make it difficult to meet protein requirements to maintain or build muscle mass. Furthermore, people may experience significant drops in energy and concentration, making the one meal a day approach difficult to sustain alongside the demands of a standard school or workday. Regarding digestive health, forcing an entire day’s worth of calories into a single meal could lead to bloating and indigestion.

So, what can we do?

If you are drawn to the benefits of the one meal a day fasting approach, but worried about the long-term ramifications, then you may want to consider it as a periodic tool rather than a permanent lifestyle. A more sustainable "middle ground’ could be considered by mixing OMAD on busy workdays with more flexible eating windows for the rest of the week. When following a one meal a day schedule, there is the need to ensure that the meal is packed with high-quality proteins, complex carbohydrates, fruit and vegetables, and healthy fats to ensure that the body receives proper nutrition rather than relying on empty calories. A dietitian can help you with the planning. It is important to recognize that restrictive habits like OMAD can sometimes mask disordered eating patterns. Consulting a healthcare professional is recommended for anyone planning to follow this routine long-term, especially if the focus on a single meal begins to feel like an unhealthy obsession rather than a helpful tool.

I am grateful to my reader, my sister Dr. Beth Offei-Awuku, for inspiring this article.

Written by Dr. Laurene Boateng (PhD, RD)
Dr. Laurene Boateng is a Registered Dietitian and Senior Lecturer in the Department of Dietetics, University of Ghana. She is the founder and editor-in-chief of Full Proof Nutrition, a Nutrition Consultancy committed to providing reliable, evidence-based, and practical healthy eating advice through its website www.fullproofnutrition.com.  Click here to join Full Proof Nutrition WhatsApp channel to receive more educative content. Send us a mail on fullproofnutrition@gmail.com. Grab a copy of my book on healthy eating - available now on Selar (Buy HEALTHY EATING MADE SIMPLE by Laurene Boateng on Selar) and Amazon (https://amzn.eu/d/6i9OeVb).

Reference

1. Bagherniya, M., Butler, A. E., Barreto, G. E., & Sahebkar, A. (2018). The effect of fasting or calorie restriction on autophagy induction: A review of the literature. Ageing research reviews, 47, 183-197.
2. https://ph.megawecare.com/good-health-by-yourself/nutrition/one-meal-a-day-omad-diet