How many calories should I eat if I eat one meal a day?

October 31, 2025 •

5 min read

According to U.S. dietary guidelines, adult daily calorie needs can range from 1,600 to 3,000 calories depending on age, sex, and activity level. If you eat one meal a day, your calorie intake is still determined by these same factors, but concentrated into a single, nutrient-dense meal to fuel your body correctly.

Quick Summary

The ideal calorie count for a one-meal-a-day plan is highly individual, depending on your Total Daily Energy Expenditure (TDEE), health goals, and activity level. Calorie needs typically range from 1,500 to 2,500+, with a focus on nutrient density to avoid deficiencies.

Key Points

Calculate Your TDEE: The number of calories for an OMAD plan should be your Total Daily Energy Expenditure (TDEE), adjusted for your weight goals.
Prioritize Nutrient Density: Since you're only eating once, the meal must be rich in protein, healthy fats, complex carbs, vitamins, and minerals to prevent deficiencies.
Avoid Undereating: Don't drop below 1,200 calories in your single meal, as this can lead to nutrient inadequacies and adverse health effects.
Stay Hydrated: Consuming plenty of water and other calorie-free beverages throughout the fasting period is crucial to manage hunger and maintain hydration.
Monitor Your Body: Pay close attention to side effects like fatigue, dizziness, or irritability. If they persist, OMAD may not be suitable for you.
Consult a Professional: Always speak with a doctor or registered dietitian before starting a restrictive diet like OMAD, especially if you have pre-existing health conditions.

Your Calorie Needs Are Not One-Size-Fits-All

Determining the correct number of calories to eat in one meal a day (OMAD) is a personalized process. There is no magic number that applies to everyone. The appropriate amount depends on several factors, including your age, sex, current weight, height, and activity level. The core principle is that your total daily energy expenditure (TDEE) remains the same, regardless of how you distribute your meals. You simply consume your entire day's calories within a single eating window, typically one to two hours.

To figure out your precise needs, you must first calculate your TDEE. This involves two main steps: calculating your Basal Metabolic Rate (BMR) and then adjusting for your activity level.

How to Calculate Your OMAD Caloric Target

First, estimate your BMR using a reliable formula, such as the Mifflin-St Jeor equation. While online calculators simplify this, understanding the components is key:

For Men: $(10 weight[kg]) + (6.25 height[cm]) - (5 * age[years]) + 5$
For Women: $(10 weight[kg]) + (6.25 height[cm]) - (5 * age[years]) - 161$

Next, multiply your BMR by an activity factor to determine your TDEE, which is the total number of calories you need to maintain your current weight.

Sedentary (little/no exercise): BMR x 1.2
Lightly Active (light exercise/sports 1-3 days/week): BMR x 1.375
Moderately Active (moderate exercise/sports 3-5 days/week): BMR x 1.55
Very Active (hard exercise/sports 6-7 days a week): BMR x 1.725

For weight loss, a modest calorie deficit of around 500 calories per day is often recommended, but it is crucial not to dip below 1,200 calories to avoid undernourishment. For weight gain, a caloric surplus is needed. Ultimately, your OMAD calorie count is simply your TDEE, adjusted for your weight goal, consumed in one sitting.

Making Your Single Meal Nutritionally Complete

The most significant challenge with OMAD is ensuring you consume enough nutrients in one meal. Since you are not eating for 23 hours, your single meal must be a powerhouse of nutrition. Simply eating a large portion of junk food will not work and can lead to nutrient deficiencies and potential health issues.

Core Components of a Balanced OMAD Meal

To ensure your meal is nutritionally complete, focus on these food groups:

Protein: Lean protein sources like chicken, fish, tofu, and beans are essential for muscle maintenance and satiety.
Complex Carbohydrates: Include whole grains like quinoa, brown rice, or sweet potatoes for sustained energy.
Healthy Fats: Healthy fats from avocados, nuts, seeds, and olive oil help with nutrient absorption and hormone regulation.
Fiber-Rich Vegetables: A large portion of your plate should be filled with various vegetables like broccoli, spinach, and bell peppers for vitamins, minerals, and digestive health.
Fruits: Include fruits for additional fiber and micronutrients.

Sample High-Calorie Meal Ideas

To meet a higher calorie target, consider dense and nutritious options:

Grilled salmon with a large serving of roasted vegetables (e.g., broccoli, sweet potatoes) drizzled with olive oil, a side of quinoa, and a mixed berry salad with almonds.
Chicken stir-fry with a variety of colorful vegetables and brown rice, topped with a generous sprinkle of sesame seeds and a drizzle of peanut sauce.
A hearty lentil soup or chili with a side of whole-grain bread and a large green salad with avocado.

Navigating the Risks of a Restrictive Plan

While OMAD can be effective for weight management, it is an extreme form of intermittent fasting and comes with potential risks. Long fasting periods can cause feelings of extreme hunger, fatigue, irritability, and even dizziness due to blood sugar fluctuations. There's also a risk of losing lean muscle mass alongside fat, especially if adequate protein intake is not prioritized.

It is vital to monitor your body's response and seek medical advice before beginning any restrictive diet, especially if you have underlying health conditions like diabetes, blood pressure issues, or a history of eating disorders. Proper hydration with water and non-caloric beverages is also non-negotiable throughout the fasting period. A balanced diet within the eating window is the only way to mitigate potential nutrient deficiencies.

Comparison: OMAD vs. Traditional Eating Patterns


Feature	OMAD (One Meal a Day)	Traditional Eating (Multiple Meals)
Calorie Intake	All calories consumed within a 1-2 hour window.	Calories spread across 2-3 main meals and snacks.
Satiety	Can lead to intense hunger between meals; the single meal needs to be very large to feel full.	More consistent satiety levels throughout the day with regular food intake.
Metabolic Effect	Triggers metabolic switching to burn stored fat after a long fast.	Keeps blood sugar and insulin levels more consistent, with less pronounced fasting periods.
Nutritional Challenges	High risk of nutrient deficiencies if the single meal is not carefully planned and nutrient-dense.	Easier to meet daily nutritional requirements by diversifying food intake across multiple meals.
Sustainability	High dropout rate due to social inconvenience and difficulty in meeting nutritional needs long-term.	Generally considered more sustainable and easier to integrate into social norms.
Potential Risks	Muscle loss, blood sugar crashes, increased cholesterol and blood pressure risk.	Fewer metabolic risks, provided the diet is balanced. Overeating is a common risk.

Conclusion: Prioritize Nutrients, Not Just Calories

Ultimately, figuring out how many calories you should eat if you eat one meal a day is a personal calculation that starts with your TDEE. For many, this will fall within the 1,500-2,500 calorie range, but it must be tailored to your specific goals, whether that's weight loss or maintenance. More important than the sheer number of calories, however, is the nutritional density of that single meal. A well-planned OMAD meal must be packed with protein, healthy fats, complex carbohydrates, and a wide array of vegetables to prevent nutrient deficiencies and support overall health. OMAD is an extreme dietary approach, and while some may find it beneficial for short-term weight loss, it presents significant risks and sustainability challenges. Always listen to your body and consult a healthcare professional before committing to such a restrictive eating pattern to ensure it aligns with your health needs and goals.

For more detailed information on calculating your caloric needs, consider using a tool like the one found on Mayo Clinic's website: https://www.mayoclinic.org/healthy-lifestyle/weight-loss/in-depth/calorie-calculator/itt-20402304.

Frequently Asked Questions

To calculate your needs, first determine your Basal Metabolic Rate (BMR) using a formula like Mifflin-St Jeor. Then, multiply your BMR by an activity factor to get your Total Daily Energy Expenditure (TDEE). This total is your calorie goal for your single meal.

Yes, weight loss on OMAD occurs when you create a calorie deficit, meaning you consume fewer calories than your TDEE. However, it's not recommended to eat less than 1,200 calories a day, as this can be dangerous and lead to nutritional deficiencies.

Your single meal should be packed with nutrients. Focus on a balanced plate of lean protein, complex carbohydrates, healthy fats, and a large quantity of fiber-rich vegetables and fruits. Avoid relying on processed, high-calorie junk foods.

Yes, OMAD can pose risks including potential nutrient deficiencies, loss of lean muscle mass, extreme hunger, and blood sugar fluctuations. It can also cause fatigue, irritability, and may not be sustainable long-term for many people.

Some studies show short-term weight loss benefits from OMAD, but it is not necessarily more effective than other forms of calorie restriction over the long term. Many people find less restrictive intermittent fasting methods, like 16:8, to be more sustainable and safer.

During your 22-23 hour fasting window, you should drink plenty of non-caloric beverages to stay hydrated. This includes water, black coffee, and unsweetened tea.

Managing hunger is a common challenge. Staying busy and hydrated can help. Some also find that starting gradually with shorter fasting windows (e.g., 16:8) helps their body adapt to the pattern. Ensuring your one meal is satiating and nutrient-dense is also key.