One Meal A Day, or OMAD, is an eating pattern that compresses all of a person’s daily caloric intake into a short window, typically lasting about one hour. This approach is an extreme form of time-restricted eating, with the remaining 23 hours spent fasting. While the method focuses heavily on when you eat, the success of OMAD for any goal—whether maintenance, weight loss, or muscle gain—fundamentally depends on how much and what you consume during that single meal.
Determining Your Baseline Caloric Requirement
The foundational number for any dietary approach is the Total Daily Energy Expenditure (TDEE), which estimates the total number of calories your body burns in a day to maintain your current weight. This TDEE is the target for weight maintenance and serves as the starting point for creating a calorie deficit or surplus. TDEE is composed primarily of your Basal Metabolic Rate (BMR) and your activity level factored in.
BMR represents the energy required for basic life-sustaining functions, such as breathing and circulation, while the body is at rest. This rate accounts for the majority of the calories burned daily, and it is calculated using variables like age, height, weight, and sex. The TDEE then adjusts this BMR by multiplying it by an activity factor that accounts for exercise and non-exercise activities like walking and daily chores.
For most people, the simplest method for estimating TDEE is using a reliable online calculator. These tools require inputting physical statistics and selecting an activity level, ranging from sedentary to extra active. It is important to be accurate about daily movement, as overestimating activity leads to an inaccurate baseline number. This calculated TDEE represents the calorie count needed to keep your current weight stable, forming the neutral target for your single OMAD meal.
Adjusting Your Calorie Target Based on Goals
Once the maintenance calorie number (TDEE) is established, it must be strategically adjusted to align with your specific body composition goals. Consuming calories equal to your TDEE results in weight maintenance, provided the calculation is accurate and activity levels remain consistent. Therefore, the calorie count of your single daily meal must align precisely with the calculated TDEE.
If the goal is weight loss, you must create a caloric deficit by consuming fewer calories than your TDEE. A common recommendation for safe and sustainable fat loss is to aim for a moderate deficit of 500 to 1,000 calories per day below your TDEE. This adjustment typically results in a weight loss rate of one to two pounds per week. It is important to avoid overly extreme restriction, as a too-large deficit can lead to chronic fatigue and hormonal imbalances.
For those looking to gain weight, particularly muscle mass, a caloric surplus is necessary. Experts generally recommend adding a modest surplus of 250 to 500 calories above the maintenance level. This controlled surplus provides the extra energy required to fuel the muscle-building process. Regularly re-evaluating your TDEE and calorie intake is necessary, as energy needs change when body composition evolves.
Prioritizing Nutrient Density in Your OMAD Meal
The challenge of OMAD shifts from calculating the correct calorie count to successfully consuming that entire amount, along with all necessary nutrients, in a single sitting. Nutrient density is therefore paramount, as the meal must provide sufficient energy without relying on “empty calories” from highly processed foods. A well-balanced OMAD meal must contain a healthy mix of protein, complex carbohydrates, and healthy fats to support satiety and overall bodily function throughout the 23-hour fast.
Adequate protein intake is important for muscle repair and growth, and it contributes significantly to feelings of fullness, helping to manage hunger during the fasting window. Complex carbohydrates, such as whole grains, vegetables, and fruits, are necessary sources of energy and dietary fiber. This fiber is essential for digestive health, a common concern when consuming a large volume of food at once.
Healthy fats, like those found in avocados, nuts, and olive oil, are important for satiety and aid in the absorption of fat-soluble vitamins. Beyond the macronutrients, the single meal must be diverse to ensure the body receives a wide range of vitamins and minerals, often referred to as micronutrients. Focusing on whole, unprocessed foods helps maximize the intake of these essential micronutrients, preventing deficiencies that can arise from such a restrictive feeding schedule.