Calorie Deficit: Why You Need It

Written by Noleen Arendse

A calorie deficit is when you eat fewer calories than your body needs to maintain its weight. A safe calorie deficit is between 500 – 1000 calories. This will allow you to lose weight at a steady and sustainable pace. 

This article covers all the key points that you need to know about a calorie deficit plus a few tips to help you cut back on calories. 

Calorie deficit

Table Contents

What is a calorie deficit?

A calorie deficit occurs when you eat or drink fewer calories than your body needs to maintain its current weight.

The body uses calories for energy. When we eat more than we burn, the energy is stored as fat. 

When we eat fewer calories than we burn, the body has to tap into fat reserves to get the energy it needs instead of getting it from something we’ve consumed. This results in weight loss

If you want to lose weight, you’ll need to be in a calorie deficit over a sustained period. 

A calorie deficit is when you eat fewer calories than your body needs to maintain its current weight. 

How much calorie deficit do I need to lose weight?

As a general guideline, a calorie deficit of 500 to 1,000 calories per day is recommended for sustainable and healthy weight loss. 

The 500 – 1000 calorie guideline is based on the fact that 1 pound of body weight is about 3500 calories. When you eat 500 calories less per day, in a week, you should lose about 1 pound of fat (0.5kg). If you eat 1000 less calories, theoretically you should lose about 2 pounds (1kg).

However, research has shown that this is not always the case. Not everyone will lose exactly 1 pound of fat a week. Some people might lose more and others might lose less. It’s important to keep in mind that this is a guideline and results can vary rather than have the expectation that you’ll lose exactly a pound of fat a week. 


How do I calculate my calorie deficit?

There are a number of ways to calculate your calorie deficit. The starting point is to work out how many calories you need to maintain your weight. 

An easy way to do this is to multiply your current body weight (in pounds) by 15. This is roughly how many calories per pound of body weight you need to maintain your weight if you are moderately active. (Moderately active – at least 30 minutes of exercise daily such as brisk walking and climbing stairs.)

For example, if you are 5 ft 4 inches and you weight 155 pounds, you’ll need to eat about 2325 calories a day to maintain your weight. However, to lose weight steadily and safely to get down to healthy BMI, you’ll need to eat about 1825 calories a day. This will create a calorie deficit of 500 calories. 

To work out what calorie deficit will help you lose weight, it’s best to use a calories to lose weight calculator like the one in: How many calories should I eat to lose weight?

The calculator will help you work out how many calories you need to maintain your weight, lose weight and lose weight fast.

It uses your height, weight and activity levels to work this out. 

In the example on the right, the person would need to eat about 1700 calories to maintain their weight, 1350 calories to lose weight and 1000 calories to lose weight fast.

It’s not wise to lose weight fast because, usually, as soon as you start to eat your usual diet, you’ll gain it back plus a bit extra.

Example of calories to lose weight calculator

Do you lose a pound a week with a 500 calorie deficit?

Theoretically, creating a calorie deficit of 500 calories per day through your diet alone can potentially result in a weight loss of approximately one pound (0.5 kg) per week.

However, keep in mind that this might not be the case for everyone. Research has shown that weight loss can vary between individuals and can also fluctuate from day to day. Weight loss is influenced by several factors, including your metabolism, body composition, activity level, and overall health. 

Although the calorie deficit through diet is the most effective way to lose weight, combining it with exercise will not only burn more calories but also improve your health. 

In reducing your calories, make sure you eat a healthy balanced diet so that you body has adequate nutrition. If you have a medical condition or specific medical needs, it’s best to consult a registered dietician for help. 

A calorie deficit of 500 calories will help you lose weight in a healthy way. Use a calories to lose weight calculator to work out your calorie deficit.

Is calorie deficit good for fat loss?

Yes, a calorie deficit is an effective way to lose fat. When you create a calorie deficit by eating fewer calories than you need, your body is forced to use stored energy (such as fat reserves) to make up for the shortfall. This will cause you to lose weight and tap into your fat reserves. 

What is a safe calorie deficit?

A safe calorie deficit for most people is generally around 500 to 1,000 calories per day. This range allows a gradual and sustainable weight loss of about 1 to 2 pounds (0.5 to 1 kg) per week.

While it might be tempting to drastically reduce your calorie intake for fast results, it’s important to approach a calorie deficit with moderation and balance. A very low calorie diet can have a negative effect on your health and put you at risk of nutrient deficiencies, muscle loss and  potentially slow your metabolism. 

Severe calorie restrictions are challenging to sustain over the long term and can negatively impact overall well-being. In fact, it can lead to yo-yo dieting – a cycle of weight loss and weight gain that can have detrimental effects on your health. 

The best way to lose weight and to keep it off is to turn healthy eating and exercise into a way of life. 

A calorie deficit is an effective strategy to lose weight. However, the deficit should be moderate to prevent rapid weight loss and weight gain.

What are the dangers of calorie deficit?

While a calorie deficit can help you lose weight, there are some dangers and risks to excessive or prolonged calorie deficits.

Nutrient deficiencies

Severely restricting calories can lead to inadequate consumption of essential nutrients such as vitamins, minerals, and macronutrients. This can lead to deficiencies and negatively impact your overall health, immune function, and energy levels.

Muscle loss

When you have a calorie deficit, your body needs fuel and may break down muscle tissue for energy.

Muscles need energy and burn more energy (even at rest) than fat. A loss of muscle can therefore slow your metabolism, decrease your strength and affect your fat-to-muscle ratio.

Slowed metabolism

Prolonged calorie deficits can send a signal to your body that you are in a state of famine. This can lead to your body slowing down your metabolism which can make it harder to lose weight. 

Hormonal imbalances

Severely restricting calories can upset the hormonal balance in the body, particularly affecting hormones related to hunger, satiety, and metabolism. This can lead to increased appetite, food cravings, and difficulty managing weight in the long run.

Psychological and emotional effects

Extreme calorie deficits can lead to increased feelings of deprivation, low energy, mood swings, and poor concentration. This can negatively affect your emotional well-being, your relationship with food, and your ability to stick to a healthy lifestyle.

To prevent the above risks, it’s important to approach a calorie deficit in a balanced and sustainable way.

Aim for a moderate calorie deficit, focus on nutrient-dense foods, and exercise regularly. If you need help, consult a registered dietician who will be able to create a personalized plan for you and help you stick to it. 

Extreme calorie restriction for long periods can lead to nutrient deficiencies, a comprised immune system, loss of muscle mass, hormonal imbalances and upset your mental health.

How much of a calorie deficit is too much?

A calorie deficit becomes too much when it is extreme or unsustainable. This can negatively impact your health, well-being, and long-term weight management.

Here are some general indicators that suggest a calorie deficit may be excessive.

Rapid weight loss

If you’re losing more than 2 pounds (1 kg) per week on a consistent basis, it could indicate that your calorie deficit is too much. Rapid weight loss increases the risk of muscle loss, nutrient deficiencies, and other health issues.

If you’re losing weight rapidly without dieting, it’s best to consult your healthcare practitioner as this could indicate an underlying health condition. 

Excessive hunger and food cravings

When you are in a calorie deficit, you might occasionally feel hungry or crave certain foods. However, if you are constantly hungry, craving certain foods, or are struggling with obsessive thoughts about food, it may indicate that your calorie deficit is too much or that you’re not receiving adequate nutrients. 

Lack of energy and fatigue

While it’s usual to experience some fatigue during a calorie deficit, persistent and extreme tiredness can indicate that your calorie intake is insufficient to support your energy needs. This can negatively impact your daily activities, mood, and overall well-being.

Decreased strength and muscle loss

If you notice a significant decrease in muscle mass or a loss of strength, it could be a sign that your calorie deficit is too much. Losing muscle mass can potentially slow down your metabolism and prevent long-term weight management.

Hormonal disruptions and irregular menstrual cycles

Severe calorie deficits can disrupt hormone production that can lead to irregular menstrual cycles in women. This can indicate that your body is under stress and may have negative effects on your reproductive health and overall hormonal balance.

Always prioritize your health and well-being when aiming to lose weight. Avoid extreme calorie deficits below 1,200 calories per day for women and 1,500 calories per day for men. As discussed there can be an increased risk of nutrient deficiencies and other health complications.

A calorie deficit can be too much if you lose weight rapidly, feel constantly tired, have excessive food cravings, notice a loss of muscle and muscle strength plus your hormonal cycle is disrupted.

Why am I not losing fat in a calorie deficit?

There could be several reasons why you’re not losing fat when in a calorie deficit. These reasons can vary between individuals. It’s best to seek professional help if you are struggling to lose weight. 

Here are some of the factors that might prevent you from losing fat when in a calorie deficit. 

You might not be tracking your calories accurately and consistently

The best way to track your calories is to weigh everything that you eat, including sauces or spreads. Not only will this help you find hidden calories but will also make you more aware of what you eat. 

For example, if you’ve made yourself some tuna and mayo salad and have used regular mayo (but not recorded it), you will have an additional 94 calories that you haven’t recorded. 

Use an app such as My Fitness Pal to record everything that you eat so that you have a more accurate reflection of the number of calories you are actually eating. 

Do this consistently for at least a month to pick up patterns or perhaps food groups that are causing the extra calories. 


You might have hit a plateau

It’s quite usual for your weight loss to stop and remain consistent at a certain weight for a period of time. This is known as a weight loss plateau. During this time, don’t give up. Aim to stick to your diet and exercise for a little longer or include more activity into your daily life. It might also be time to drop that one “treat” for a period to help shift the balance again. 

Underlying health condition

If you have been consistently tracking your calories and exercising but the weight is not budging, it might be a good idea to have a health check. There might be an underlying condition or a hormonal imbalance causing this to occur. 

If you have a pre-existing health condition, seek professional assistance before starting a calorie deficit diet. 

Weight loss is a journey and the best way to lose weight and keep it off is to change your lifestyle into a healthier, more active lifestyle. If recording calories is not your thing, then joining an app like Joggo, might be a good option. 

Joggo is a weight loss running app that not only give you an exercise program but also creates a customized meal plan plus recipes for you. For more, have a look at our detailed Joggo Review

If you are on a calorie deficit but the weight isn't budging, make sure you are recording all your calories. If you've hit a plateau, stick to your diet and increase your activity levels. Seek professional help if you are concerned about your health.

How to create a calorie deficit

There are two ways to create a calorie deficit: reduce your calorie intake and increase your calorie expenditure through exercise. The most effective strategy is a combination of the two.

How to cut calories

Reducing your calories doesn’t need to be complicated. A few simple swaps, will go a long way. Even reducing treats to once a weekend instead of everyday can help! 

One of the easiest ways to reduce your calorie intake is to remove all processed sugars and sugary drinks.

For example, while not the best for your health, doing a simple swap from regular cola to a sugar-free version, can save you 123 calories.  

This also includes fruit juices. A simple swap from a glass of fruit juice to a whole fruit, will save you calories while still ensuring you get the vitamins plus fiber in the fruit. 

Another way to cut calories is to reduce your serving size of carbohydrates and replace it with vegetables. Instead of loading your plate with rice or chips, load it with vegetables and protein, with a smaller serving of rice. Even better, swap the rice for cauliflower rice! 

Lastly, keep the treats to the weekend. If you are used to having dessert every night, plan to have it on the weekend instead! Not only will this help you reduce your daily calories but it can also serve as a reward for a stricter diet in the week. 

For more weight loss tips, head over to How many calories should I eat to lose weight?

Become more active

Apart from reducing calories, increasing your calorie expenditure can help you lose weight by burning extra calories. However, keep in mind that research has shown that the calorie deficit through diet is the key factor when it comes to losing weight. 

Here are few ways to increase your activity levels:

  • Aim to exercise everyday – even if it’s initially a 30 minute walk. As you grow stronger, increase the distance or the pace. 
  • Include strength training – building muscle will burn more calories even when you’re doing nothing. 
  • Add incidental exercise into your day – simple changes can add up. For example, park the car further away so that you need to walk to the shop, take the stairs instead of the elevator, and choose to stand and work instead of sitting. 

Simple changes to your lifestyle will make you more active and help you to burn more calories. When it comes to exercise, choose an activity that you love doing so that it’s sustainable. 

It's best to use a combination of diet and exercise to create a calorie deficit. The most effective program is one that is sustainable for you and becomes part of your lifestyle.


A calorie deficit occurs when you eat fewer calories than your body needs to maintain its weight. This forces your body to convert energy reserves, such as fat, into energy.

A moderate deficit of 500 – 1000 calories per day is the recommended calorie deficit to lose weight sustainably. 

Although not impossible, it can be challenging to create a calorie deficit through exercise alone. A calorie deficit in diet has also been shown to be more effective at weight loss than exercise. 

Yes, if you are not giving your body adequate nutrients such as protein, it will break down muscle as fuel. 

A calorie deficit is not suitable for everyone, especially those who have underlying medical conditions or who are already underweight. If you have any concerns, it’s best to consult your healthcare practitioner before starting a weight loss program. 

Overall Summary

  • A calorie deficit occurs when you eat fewer calories than you need to maintain your weight. 
  • If you want to lose weight, then it’s a good idea to eat a diet that has a calorie deficit. 
  • Aim to eat 500 – 1000 calories less than you usually consume to lose weight safely.
  • Always put your health first and consult a healthcare practitioner before starting a weight loss program.