What Is a Calorie Deficit?

woman tracking calories with an app and eating lunch

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You create a calorie deficit when you take in fewer calories than you burn. This is also sometimes called an energy deficit because calories are a unit of heat or energy. Regardless of the terminology, a caloric deficit is an important factor in losing weight.

It should be noted, however, that not all nutrition experts or researchers agree that shedding excess weight is as simple as cutting a certain number of calories per day. Below we explain calorie deficits and how to keep realistic weight loss expectations when reducing your food intake.

What Is a Calorie?

A calorie is a unit of energy. Calories in food provide energy in the form of heat so our bodies can function even when they are at rest. The total number of calories you burn daily is called your total daily energy expenditure or TDEE.

When TDEE is calculated, it includes calories burned through exercise and non-exercise movement and calories burned during digestion are called the thermic effect of food or TEF. It also includes calories you burn to maintain essential bodily functions, such as breathing and blood circulation.

To figure out how many calories your body needs to perform basic functions, you can estimate your resting metabolic rate (RMR). Once you know your RMR, you can use a calculator to estimate your total daily energy expenditure. You can also get tested in a lab setting or health club to determine these numbers.

What Is a Calorie Deficit?

You create a calorie deficit if you take in fewer calories than your body needs to perform all of its necessary functions. For instance, if you use 2,000 calories today but only take in 1,800, you have a deficit of 200 calories.

When a calorie deficit exists, your body gets energy or fuel from stored fat. In this case, stored fat is stored energy. Your body can use it to keep moving instead of using energy from food. When your body burns fat for energy, you lose weight.

Calculate Daily Calorie Needs

To create a calorie deficit, you'll need to know your daily calorie needs to maintain your weight. Maintaining your current weight means you are not eating more or fewer calories than your exact needs to not gain or lose weight. Your maintenance calories are the starting number you will use to determine a calorie count for creating a deficit.

You can use the below calculator to determine your daily calorie needs:

Creating a Calorie Deficit for Weight Loss

There are differing opinions as to calorie deficits and how they contribute to weight loss that is healthy and sustainable. Some nutrition-based organizations suggest you need a calorie deficit of 3500 calories per week to lose one pound of bodyweight. For instance, the National Institute of Health suggests cutting 500 calories daily to achieve this goal.

Research suggests that the notion of 3,500 calories in a pound of bodyweight dates back to the 1950s, when Max Wishnofsky, a New York healthcare provider, wrote this in a report. Since that time, many top health officials and agencies have continued to echo this statement.

If you've tried to lose weight by cutting calories, you may have experienced these effects. However, many opponents of this ideology say that losing weight is not as simple as creating a specific calorie deficit.

When reducing calories, your body has several mechanisms to prevent weight loss. Your metabolism slows down, hormone levels change, hunger sensations increase, and you may become less active even without realizing it.

This effect is normal and happens because, throughout human evolution, times of famine and hunger were common. Those who could preserve energy by slowing down weight loss were more likely to survive and pass down their genes.

Weight Loss is Not Linear

When creating a calorie deficit based on numbers such as 3,500 calories per pound, you may expect linear, consistent weight loss. However, the human body is complex, and weight loss is not typically lost in a linear fashion.

In an article published by the International Journal of Obesity, researchers explain that the idea of a 3,500-calorie deficit resulting in the loss of one pound of fat "grossly overestimates actual weight loss."

They back this up with several studies where subjects reduced their caloric intake by a certain amount each day yet lost significantly less weight than predicted under the 3,500 calorie rule. Based on their findings, they concluded that losing weight is more of a curve than a line.

In other words, even though subjects continued to eat fewer calories than they expended, their weight loss started to taper off versus continuing at its initial rate. Some dietitians agree, adding that several factors affect weight loss, from gender to exercise habits and more, and calorie deficits are only one factor.

Set point theory is one reason why weight loss can seem to settle back at a particular weight. The body prefers to remain in homeostasis, meaning, it aims to keep your body weight the same, regardless of changes you make to your energy balance. It does this by slowing the metabolism, decreasing NEAT, increasing hunger and more.

The Bottom Line

One thing that experts agree on is that a calorie deficit is necessary for weight loss. However, the amount it can help varies based on several factors. Keeping this in mind can help you maintain realistic expectations when trying to lose weight.

Health at Every Size

The concept of health at every size (HAES) is that you can seek and obtain a healthy lifestyle regardless of your body size or weight. It is considered a weight-neutral approach to health and breaks away from diet culture and its negative mental health impacts.

In terms of calorie counting, HAES rejects this type of strict monitoring of energy balance and instead encourages intuitive eating practices and body acceptance. It's important to note that if you aim to make body composition changes, including weight loss or gain, intuitive eating has not been shown to be very effective due to the body's natural inclination to remain the same (homeostasis).

How to Create a Calorie Deficit

While it seems simple to create a calorie deficit and lose weight, many people struggle with the process because it is not as easy as it seems. The good news is that you don't have to restrict yourself with a fad diet or juice fast. Creating a calorie deficit for weight loss should be based on improving your health and wellbeing, not deprivation.

Adjust Portion Sizes

If you adjust your portion sizes, improve snacking habits, and choose nutrient-rich, filling foods at mealtime, you will likely consume fewer calories each day naturally while increasing your intake of nutrient-dense foods that keep you energized and satisfied.

It is important not to eat too little when trying to lose weight since this can reduce the likelihood of sustainable weight loss. Instead, focus on increasing your intake of high volume, filling foods high in nutrients rather than concentrating on cutting out foods.

Get Active

The number of calories your body needs daily depends on your activity level. This includes the exercise you do and also your non-exercise physical movement. If you increase the number of calories your body needs but still consume the same number of calories from food, you will have a calorie deficit. 

Physical activity is incredibly beneficial to your health, far beyond the effects of potential weight loss. Focusing on adding movement that you enjoy to your days helps improve your mental and physical wellbeing. Weight loss may occur naturally as a result of your increased activity without feeling as though exercise is only a tool to burn calories.

Exercise also affects your hunger and appetite. Moderate to intense activity can blunt hunger without increasing the amount you eat later in the day. This means that adding physical activity can increase calorie burn, reduce hunger, and create a natural calorie deficit without focusing on cutting calories.

Combine Healthy Eating and Exercise

Studies have found that, although both calorie deficits and exercise can help with short-term weight loss, the best way to maintain weight loss long-term is by combining them. Taking this approach creates a calorie deficit in two ways, providing optimal results.

A Word From Verywell

To lose weight, you must create a calorie deficit, but that doesn't mean you have to focus on cutting out your favorite foods and depriving yourself. Instead, focus on adjusting portion sizes, adding nutrient-rich filling foods, and participating in physical activity you enjoy.

You can also get help from a registered dietitian. These professionals can design an effective meal plan that meets your personal needs. Over the long term, a program created based on your individual needs is usually a plan you are most likely to stick to.

Frequently Asked Questions

  • What happens what you consume fewer calories than you burn?

    When you consume fewer calories than you burn, you will lose weight. This weight will come from body fat, muscle, and other tissue. How much weight you lose will depend on how significant of a calorie deficit you create through diet and exercise.

  • How do I calculate my calorie deficit?

    To calculate your calorie deficit, you first need to know how many calories you need to maintain your weight. Count your calories for a week while your weight remains steady. Subtract a small number of calories to get your deficit. Typically 500 calories per day are equal to one pound of loss, but this is not always accurate since the body has ways of preventing weight loss. A range of around 500 calories under maintenance is usually recommended for weight loss. Discuss this with your doctor.

  • Why am I not losing weight in a calorie deficit and working out?

    If you are not losing weight while working out and you believe you are in a calorie deficit, the fact is, you are not likely in a calorie deficit. Calorie deficits, by definition, will lead to weight loss unless this is masked by water weight gain due to increased sodium intake or exercise. What may also be the case is that your metabolism has adapted, making your body more efficient and bringing you out of the deficit. You may need to reduce calories further or take a diet break altogether to allow your metabolism to adjust.

  • How can I speed up my metabolism?

    The best way to speed up your metabolism is to take a diet break if you've been dieting for a long time (longer than 3 to 4 months). It's also effective to build muscle mass and resistance train. To build muscle, however, you will need to increase your calories above maintenance to gain mass. Doing this for several weeks may help increase your metabolic rate.

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Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Rachel MacPherson, BA, CPT
Rachel MacPherson is a health writer, certified personal trainer, and exercise nutrition coach based in Montreal.