Tracking calories using a fitness app

What is a Calorie Deficit Diet? Everything you need to know

 March 4, 2024|  Aya Chawa

Implementing a calorie deficit diet involves understanding and managing your energy intake so that you consume fewer calories than your body expends.

Calorie deficit meaning

A calorie is a unit of energy that our body receives from what we eat and drink. We need energy for essential daily functions that keep us alive, like breathing, digesting, moving, etc. We also need energy to perform physical activities like running, going to the gym and any other form of exercise.

A calorie deficit means that the number of calories you burn exceeds the number of calories you eat. This approach leads to weight loss over time and can be achieved through:

  • Dietary changes.
  • Increased physical activity.
  • A combination of both.

Calorie deficit of 500 per day

Meal prepping for significant nutrition while in calorie deficit

0.45kg of fat is 3,500 calories. Therefore, to lose 0.45kg of fat you need to create a calorie deficit of 3,500kcal.

This means, to lose 0.45kg over a week, you need to create a calorie deficit of 500kcal per day (3,500kcal/7 days= 500kcal).

Thus, a deficit of 500kcal per day will result in almost half a kilo of fat loss per week.

Why only 500kcal deficit and not more?  A deficit of 500 kcal is the medically recommended limit to lose weight in a healthy way, without affecting your energy levels or losing muscle mass along with the fat.

If you eat much less than your daily needs, you will:

  • Feel hungry and tired, which will also affect your performance if you plan on working out.
  • Slow your metabolism and make losing weight difficult.
  • Start losing muscle mass, which is not good for your health.

Calorie deficit to lose 1kg per week

To lose 1kg of fat in a week, a calorie deficit of around 7,770kcal should be achieved. Meaning a 1,110kcal deficit per day.

Now in certain cases weight-loss of 1kg per week is acceptable. For example, for people with a BMI of 30kg/m2, especially in the first few weeks where a rapid drop is typical.

However, it is important to keep in mind that everyone responds to a diet change differently making it difficult to predict weight-loss results accurately.

How do I calculate my calorie deficit?

To calculate your calorie deficit, you need to calculate your TDEE (total daily energy expenditure).

Your total daily energy expenditure (TDEE) is how many calories you burn daily. This depends on several factors, like:

  • Age
  • Gender
  • Height
  • Weight & body composition
  • Physical activity level

You put this information into Mifflin St Jeor equation which, based on studies, provides a close estimate of true BMR (basal metabolic rate).

The equations for males and females are:
: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
Women: (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161

Your TDEE takes your activity level into account by multiplying your BMR value by an activity multiplier. This is true even for those with a sedentary lifestyle.

Activity Level Number Description
Sedentary 1.2 People who work desk jobs and engage in very little exercise or chores.
Lightly active 1.375 People who do chores and go on long walks/engage in exercise at least 1 to 3 days a week.
Moderately active 1.55 People who move a lot during the day and work out (moderate effort) at least 3 to 5 days a week.
Very active 1.725 People who play sports or engage in vigorous exercise on most days.
Extra active 1.9 People who do intense workouts 6 to 7 days a week with work that demands physical activity.

Now let’s say I want to lose weight. I start by:

  • Calculating my BMR:
    (10 × 52) + (6.25 × 164) – (5 × 25) – 161 = 1,259kcal
  • I then multiply it with the appropriate activity factor level to get my TDEE:

1,259kcal x 1.55 = 1,951kcal

  • Lastly, I subtract 500kcal to create a deficit:

1,951kcal – 500kcal = 1,451kcal to lose 0.45kg over a week.

Calorie deficit but no weight loss?

Man using his fitbit to track his daily calories

6 Potential reasons you are not losing weight in a calorie deficit:

  • You’re expecting quick results. Weight loss takes hard work, consistency, and most importantly patience.
  • You’re eating less but could make healthier choices.
  • You’re not keeping track. Some things might be “healthy” but are calorie dense.
  • You’re not getting enough sleep. Which causes hormonal imbalances that make losing weight harder.
  • You’re under stress. Which affects the body in many ways.
  • There’s a medical reason. Some conditions, like those that affect your hormone levels, insulin, or BP, can make it difficult to lose weight.

Calorie deficit eating plan

Best way to ensure you are on the right plan is:

  • Track your calories by weighing your food. Now this might not be fun at first but after a few days you will visually learn the portion sizes adequate for you.
  • Eat a rainbow! The more colour your plate includes the better. You ensure you are getting different vitamins, minerals, and antioxidants.
  • Know your macros. Where your calories are coming from is just as important as how much you are consuming. A simple distribution can be 40-50% of calories from complex carbs, 25-35% of calories from protein, and 25-35% of calories from healthy fats.

Is a calorie deficit good or bad?

Man doing a deadlift as part of his workout routine to create a calorie deficit

A calorie deficit is neither good nor bad. It is merely a metric you can use to manage your energy intake, which you can then manage to decrease, maintain or increase your weight. There are many fad diets out there that could harm your efforts to lose weight and have side effects like deficiencies and irritability. A calorie deficit that includes all the nutrients your body needs, in combination with a healthy lifestyle that involves physical activity and proper rest is the most effective way to lose weight in a healthy manner.

After all, a calorie deficit is followed for a period of time to reach a certain weight goal. After you achieve your goal, you shift to a maintenance plan.  If you’d like to know more about avoiding diet rebound weight gain, see How To Avoid Diet Rebound


 March 4, 2024 | Aya Chawa
Aya Chawa

About the Author

Aya joined Kcal in 2021, where she has been dedicatedly assisting Clients in optimising their performance through proper nutrition. As a certified Fitness Instructor and Personal Fitness Coach, she understands the importance of an active lifestyle in conjunction with a balanced and nutritious diet, both crucial for weight management and disease prevention. Aya obtained her bachelor’s degree in nutrition & Dietetics from Lebanese American University in Beirut, where she also minored in Food Science. During her academic journey, her passion for nutrition led her to work as a dietetic intern in Beirut. She firmly believes in the power of a holistic approach when it comes to wellness. By addressing the individual needs of each client, she tailors meal plans that not only enhance performance but also promote overall health and well-being.

Leave a reply

Don't waste time prepping food

Get fresh healthy meals delivered to your door and tailored to your specific nutritional needs

Order Fuel Now

Follow us on Instagram


Clean, healthy eating.
Zero prep time.

Order Fuel