Calorie Deficit: Lose weight and stay healthy

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Are you looking to lose weight and shed some excess fat? If yes, then you’ll need to be in a calorie deficit. You may be wondering what a calorie deficit is, how to calculate It and how to ensure it’s healthy right? Well, don’t worry we cover everything you need to know in this post.

What is a calorie deficit?

Calories can be a difficult concept to grasp because it’s not a physical term, it is a unit of measurement. For instance, kilograms and grams are a unit of measurement for weight, and metres, kilometres and miles are a unit of measurement for distance. Calories are a unit of measurement for energy. When you consume food and beverages, you will be eating calories, and in a different term you will be eating an amount of energy to help you do your daily activities, workout and to support a variety of bodily functions not visible to the eye like brain functioning.

A calorie deficit is achieved when you consume fewer calories to what your body requires to maintain your current weight. So in order to achieve a calorie deficit, you will need to know how many calories your body needs to maintain your weight and then reduce them depending on how much weight you’re looking to lose. We will get into that in just a second don’t worry.   

How calorie deficit works?

A calorie deficit forces body fat to break down because the body will lack enough calories from food to support your daily activities, exercise and more. Therefore, it will breakdown the fat to release fatty acids that can be used by the body for energy.

How to calculate a calorie deficit?


As we’ve previously mentioned, you will firstly need to calculate how many calories your body needs to maintain your current weight. Counting calorie deficit can be done automatically with the help of a calorie calculator, you can check out our macro-nutrient calculator which calculates not only your calories but also the macro-nutrients. However, if you’d prefer to do the calculations yourself then continue reading.

Calculating your maintenance calories:

For today’s post, we will be using the Harris-Benedict equation as it is very reliable and incorporates all aspects of your body composition. Below, you can find the summary of this equation, be careful as it varies for both men and women so make sure to calculate your maintenance calories using the correct gender calculations. So, the first step is to calculate your Basal Metabolic Rate (BMR):

MEN – (88.362 + (13.397 x body weight in KG) +4.799 x Height in CM) – (5.677 x age) = BMR

WOMEN – 447.593 + (9.247 x body weight in KG) + (3.098 x Height in CM) – (4.330 x age) = BMR

When doing your calculations, don’t forget about BODMAS! Calculate the brackets first, then add and then subtract.

Just to help you understand the equation a little easier, we’ll do an example. Let’s calculate the BMR for a 1.65m lady who is 27 years old and weighs 62kg.

447.593 + (9.247 x 62) + (3.098 x 165) – (4.330 x 27)

447.593 + 573.314 + 511.17 – 116.91

BMR = 1,415.167

Once you have calculated your BMR, it is time to multiply that figure by the activity factor. Below, you can see a number beside each activity factor and an explanation to help you determine which activity factor you fall under. Simply, multiply your BMR by the activity factor.

Activity Factors

Sedentary – 1.2 (work at an office and do not exercise)

Light Activity – 1.375 (Either you work in an active occupation eg. Waitressing or you work in an office job but sometimes exercise)

Moderate Activity – 1.55 (You may work in a sedentary job but exercise very regularly or you may simply be working at a physically demanding job eg: Labourer)

Very active – 1.725 (You may exercise most days of the week and you may work in an active occupation)

Extra active – 1.9 (You exercise every day and you work in a physically demanding job)

Just to continue with our previous example, our calculations show that our hypothetical lady’s BMR is 1,415.167 and now let’s presume that she is moderately active which is where most people will fall under. This means that we will need to multiply 1,415.167 by 1.55 as this is the number beside that activity factor.

1,415.167 x 1.55 = 2,194 (rounded up)

So, the maintenance calories are 2,194 calories per day. If our lady consumed this amount of calories per day, she will maintain her current weight. It may still fluctuate due to hormones and water retention, but she will roughly stay the same weight.

Calculating the calorie deficit:

To calculate your calorie deficit depends on how much weight you are looking to lose. A calorie deficit can have a bad impact on your metabolism which means you are likely to regain weight after you’ve decided to consume pre-diet calories. You can read more about the metabolism here. However, the point here is that you need to be careful that your calorie deficit is not too big or too high as the bigger the calorie deficit, the bigger impact on your metabolism. Also, a calorie deficit that is too big can have negative impacts on your hormones, cause the body to enter into starvation mode and even lead to malnutrition if you don’t consume an appropriate balanced diet. If this is of your concern, you can take a look at our personalised diets, we do all the hard work for you.

Moreover, a too big calorie deficit is bad due to the previously mentioned reasons. The bigger the calorie deficit, the faster you’ll lose weight but also the faster you lose weight the higher the chance you will gain weight. So you may wondering what is a safe calorie deficit? A safe calorie deficit is one that causes no more weight loss than 1-1.2lbs per week.

What deficit is required to lose 1lb of weight per week?

Over the years scientists have cracked the code. To lose 1lb of weight in 1 week, you will need to be in a 500-calorie deficit. It’s important to understand that to lose weight, you need to be in a calorie deficit consistently. You don’t lose weight from one day to another but rather over 3-7 days. Scientists have discovered that 1lb of fat is made from 3,500 excess calories, so being in a calorie deficit for 7 days will mean that you’d have lost 3,500 calories and as a result, 1lb of fat (500 x 7= 3,500).

Is calorie deficit all that matters?

a bowl of raspberries

A calorie deficit is the biggest driver of weight loss, you can lose weight without exercise just by being in a calorie deficit but the best way to shape up and tone up is through exercise.

Also, the whole calorie equation can be affected by a variety of things like medical conditions like MS and under active thyroid, certain medicines can also cause weight gain, and slow metabolism. So if you are suffering from any medical conditions or taking any medicines, make sure to read the potential side effects or ask your doctor if these can cause weight gain as there may be alternatives you can take.

Why is calorie deficit not working?

As we’ve previously mentioned, losing weight occurs over 3-7 days when you remain within your deficit consistently. If you have a cheat day, this can ruin your calorie deficit and potentially take you over your maintenance calories. Watch the video below to understand how cheat days can ruin your dieting with just 1 day, and how to prevent it whilst still enjoy your cheat day.

Youtube video on cheat days

When to stop the deficit?

A calorie deficit should not be stopped from one day to another because that only sets you up for weight re-gain. Your metabolism will not be able to handle that so avoid stopping the calorie deficit from one day to another at ALL COST if you want the weight loss to be sustainable. Instead, invest time into reverse dieting which is a diet post-diet and helps you increase calories without gaining weight. You can read about it more here.


A calorie deficit refers to eating fewer calories than what the body needs to maintain its current weight. The deficit can be achieved by either eating less food or by exercising to burn extra calories. By now you should know how to calculate your calorie deficit and how to lose 1lb of weight per week. We hope this information was helpful, let us know below in the comments.

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