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Best Ways to Calculate Calorie Deficit for Weight Loss

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Some are more accurate than others. You can calculate your daily calorie needs manually or with the use of an online calculator. For the manual calculation, the average person can simply multiply his/her present body weight by 15 to gauge just how many calories is needed on a daily basis.
The general formula for calculating a calorie deficit is:

calculate calorie deficit for weight loss

There are many eating plans that circle around calorie intake. These can range from calorie counting to ‘calories in-calories out’ (aka CICO) to a reasonably low-calorie diet.

But a principle of weight loss that remains true is maintaining a calorie deficit, or burning more calories than you consume. This weight loss method can be somewhat overwhelming, especially if you try it out for the first time, but it’s not as complicated as many think.


  • A calorie deficit means burning more calories than you consume over time.
  • A calorie deficit can be achieved by exercising more, eating less, or a combination of both.
  • Caloric needs and deficits vary for each individual and depend on factors like exercise frequency, age, metabolism, and more.
  • Creating a healthy calorie deficit is important, and it is recommended to consult a doctor or nutritionist for an accurate caloric intake evaluation.

You must know what you should and shouldn’t eat, the calorie content of different foods, and most importantly, how many calories you need to achieve and stay in a calorie deficit. Again, this can be pretty difficult or tasking.

So if you want to know more about what calories are, how to achieve a calorie deficit and the best way to calculate a calorie deficit, this article is for you.

What are calories? 

Calories are a measurement or unit of energy or heat with 1 cal. = 4.184 joule. It is the way our bodies exchange energy. Calories exist naturally in many foods and can be found in macronutrients such as proteins, carbohydrates, protein and alcohol. The calories contained in food provide the fuel needed to survive.

The body breaks down whatever food you eat and releases energy to be used immediately or stored for later, typically as body fat, depending on your need at the time. You either burn or expend the energy (mainly) through exercise. In order to maintain your weight, your body needs to take in a certain amount of calories. This leads us to the next big question:

What is a calorie deficit?

calculate calorie deficit for weight loss
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There are many ways to describe what a calorie deficit is, but all definitions allude to the same thing: a calorie deficit is simply burning more calories than you are consuming over time. It is when you absorb fewer calories than your body demands to stay at its current weight. If, for example, you are burning 1500 calories per day but consuming only 2000, you will be in a calorie deficit of 500.

The body must burn a number of calories to perform all of its essential functions to keep you alive and well daily like digestion, breathing and blood circulation. Depending on your diet and exercise, you can achieve a calorie deficit in two (or three) effortless ways:

  • By exercising more 
  • Eating less or
  • A combination of both.

A person can maintain a specific body weight during the day or week by not consuming more calories than they need. With time, the calorie reduction ultimately leads to weight loss. So, when you want to shed weight or achieve fat loss, a calorie deficit is key. 

Keep in mind that caloric needs and deficits are entirely individual and differ based on certain factors like; how often you exercise, age, genes, height, hormones, sex, weight, metabolism, and so on.

When calculating your target calorie deficit for a day, week or month(s), you must estimate the calories you consume in your food and beverage and also take account of what you burn through activity.

These two elements are very vital and individual. Never use another person’s calorie deficit plan as a yardstick to measure yours.

calculate calorie deficit for weight loss
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Creating a healthy calorie deficit can be challenging for many people. It is possible to pick an incorrect amount of calories and create a very strict calorie deficit plan to follow.

For instance, you might need 2,400 calories per day based on your weight, height and training volume (if you’re an athlete), but then assume that you only need 1,800 calories a day to keep your weight in check

For this reason, when you do decide to lose weight, you would probably create an even larger calorie deficit and remove, say, 500 calories more, having a 1,300-calorie meal plan in total. 

You really don’t have to cut out 500 calories per day from your diet just to lose weight, though. A deficit will eventually lead to weight loss sooner or later, depending on how great the deficit is. Nevertheless, a calorie deficit of 500 calories daily ensures sustainable and healthy weight loss.

Is Calorie Deficit for Everyone?

calculate calorie deficit for weight loss
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A calorie deficit isn’t for everyone, and here’s why. There are persons with certain conditions, nutritional deficiencies, or taking medications that make losing weight very difficult. So, a calorie deficit plan just does not work for them. Although creating a calorie deficit may not be a perfect science, it sure isn’t rocket science, so don’t fret.

However, you need to know that the speed rate of your metabolism is a ruling factor, as well as the type of calories you take in, like sugar which is used up more quickly and easily than fibre.

In a bid to compensate for short-term calorie changes, your body raises your metabolism temporarily when you eat more for some days and lowers it when you eat less.

How is Calorie Deficit Significant for Weight Loss? 

calculate calorie deficit for weight loss

A calorie deficit is the most important, common and necessary ingredient among others for a weight loss plan no matter what the latest diet trend might be. You could even cut on your carbohydrates, fat or fast at intervals but they all result in a calorie deficit for weight loss.

Calories are one of the main elements in weight loss or weight gain. Thus, if you consume fewer calories than you burn, the result will be weight loss. But if you take more calories than you need daily, then you will have the reverse which is calorie surplus, and then start storing fat.

READ ALSO: Easy Weight Loss Tips to Lose Weight Fast

READ ALSO: How To Make 7 Nigerian Detox Smoothie Recipes To Lose Belly Fat

Is calorie deficit enough to lose weight? 

Calorie deficit is very essential for weight loss, but it is only half the picture. Calories aren’t the only factors that affect weight. For example, if you are a sedentary person – i.e. you do a lot of sitting and only move as much as you need but do not engage in exercise or other physical activities, you will need to do more than having a calorie deficit.

In order to lose a pound or two (lb) weekly, you would need to eat 500–1,000 calories lesser than the number of calories your body needs a day.

Rest assured, cutting down on calories doesn’t necessarily mean dissatisfaction during meals. Simply substitute some foods of higher calories with foods low in calories, drink water more often and consume more fibre to feel full.

Ways to calculate calorie deficit for weight loss.

There are a number of methods to determine how many calories you regularly burn in a day, your calorie needs and an appropriate calorie deficit. Some are more accurate than others. You can calculate your daily calorie needs manually or with the use of an online calculator. For the manual calculation, the average person can simply multiply his/her present body weight by 15 to gauge just how many calories are needed on a daily basis.

The general formula for calculating a calorie deficit is Calorie deficit = calorie in – calorie out.
In the equation above, the calorie in pertains to the amount of calories consumed daily, either by food or drink. Calorie out is the number of calories the body requires to maintain its present weight.

If your calorie out is lower than your calorie in, then you have a calorie surplus and you will store fat and add weight. But if your calorie out is greater than your calorie in, you have a calorie deficit and will shed weight.

Here are simple practical ways to calculate your calorie deficit:

calculate calorie deficit for weight loss
Credit: Canva
  1. Consult a doctor or nutritionist

Speak with your doctor or nutritionist for the best and most accurate caloric intake evaluation. These professionals are able to tailor the estimate based on your person and your lifestyle. Each and every health practitioner has a slightly different or unique approach. 

Some calculate based on body measurements like height, weight, and exercise level. While some prefer to leave math out of the whole thing and focus instead on making little important changes with their patients which can naturally lead to weight loss. Some might even advise you to go for metabolic testing.

  1. Use a formula

To calculate your daily maintenance calorie intake, or the calories required to keep the same weight, use a calculator. You can start by calculating your basal metabolic rate (BMR) which is the minimal amount of calories your body burns while resting. Your basal metabolic rate and activity levels can be used to nail down your current caloric needs.

There are a lot of formulas to help you calculate your calorie needs but the Journal of the Academy of Nutrition and Dietetics published a study stating that the Mifflin-St. Jeor’s equation is indeed very accurate. Either of the formulas below are useful as well in calculating your BMR, according to sex: 

a. The Mifflin-St Jeor equation:

  • The Mifflin-St Jeor equation for men is: BMR = 10 x weight (kg) + 6.25 x height (cm) – 5 x age + 5
  • The Mifflin-St Jeor equation for women is: BMR = 10 x weight (kg) + 6.25 x height (cm) – 5 x age – 161

Once you have obtained your BMR, you can use either of the formulas below to calculate your caloric need based on your level of activity:

  • Sedentary: little or no exercise = BMR x 1.2
  • Slightly active: 1-3 days of exercise or activity weekly = BMR x 1.375
  • Moderately active: 3-5 days of exercise or medium activity/sports weekly = BMR x 1.55
  • Very active: 6-7 days of intense exercise or activity weekly = BMR x 1.725
  • Highly active: exercise or activity twice a day weekly = BMR x 1.9

b. The Harris-Benedict equation: 

This equation is very often used for comparison. The equation is BMR = 655.1 + (9.563 x weight in kg) + (1.850 x height in cm) – (4.676 x age in years).

The results vary slightly depending on the formula used. 

  1. Modify calorie intake for weight loss

When you have determined your maintenance calories, calculate the level of calorie intake you need to lose weight.  Note that a kilo of body fat is around 7,700 calories and if you want to target a 0.5-1 kilo of weight loss per week, you could do something like this:

  • 500 calorie deficit a day = 3,500 calorie deficit a week
  • 700 calorie deficit a day = 4,900 calorie deficit a week

If you have a strict healthy diet and you are not quite sure where to cut down calories, you may have to exercise harder more often. But if you are able to reduce your portions and cut down on carbs and fats in your diet, then shift your focus to a larger calorie deficit from your meal. Keep track of the calories you consume by weighing and measuring your portions. 

  1. Engage in physical activity

Modifying your diet plan is only half the battle. You will need to engage in exercises on a regular basis. Simply subtract the calories burned during exercise from the ones gained through eating. It should look like this; Food Calories – Exercise Calories = Net Calories.

For weight loss, your net calories per day should be roughly 500 calories lesser than your BMR. It can be very tasking to calculate precisely how many calories you expend through exercise because it isn’t an exact science.

  1. Use an online calculator

If you’re looking to avoid all the math, well, there are ample online calculators that can solve that. Online calculators do all the hard work and are more accurate in their calculations. A calculator will create an estimate of your calorie needs per day for losing, adding and maintaining weight. Some calculators tell you the number of calories to maintain your current weight after reaching your target. So if you’re not sure how to calculate your calorie deficit, just use an online calculator.

What are the risks of eating too little calories?

While it is important to cut down on calories, it can equally be health threatening if you starve your body of calories and become ‘calorie deficient’. Your body needs an average number of calories to properly function. If you cut down too many calories, you bear the risk of missing out on certain necessary nutrients and can experience health issues like:

  • Loss of bone mass
  • Reduced metabolism
  • Gallstones
  • Low brain energy

A few symptoms of extremely low calories include;

  • Frequent illness
  • Negative changes in overall mood/behaviour
  • Constipation
  • Difficulty sleeping
  • Inability to lose weight


A calorie deficit occurs when you consume fewer calories than you burn over a period of time. Although reducing calories is an important part of losing weight, it is not the only option you have and sometimes it is counterproductive.

Creating a calorie deficit is very essential if you hope to lose weight significantly and you can achieve this by combining your diet plan with an effective exercise routine. Focus on eating foods with very high nutritional value, drinking water often and regular exercise.

Avoid cutting down on too many calories and losing more than 2 lb. a week to evade health risks associated with low nutrition. Maintaining your calories to 500 – 1000 daily is a good fit. Anything beyond that is just wrong.

Most importantly, always consult a doctor or nutritionist before you decide to embark on a calorie-deficit journey. People with underlying health issues will need special diets to help manage their condition

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July 26, 2023 - 11:26 am

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Claire Essi

Claire Essi is a health researcher and freelance health content creator. As a health and wellness junkie, she enjoys all things related to quality lifestyle and healthy living.

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