Trying to lose weight but confused about calories? I can assure you that you are not alone. While the concept of creating a calorie deficit may seem simple in theory, “just eat less and move more”, it can be difficult to understand and implement in practice. So, here is everything you need to know; what is a calorie deficit, how it works, how to create it, and how to use it to support healthy weight loss.
What is a calorie?
A calorie is a unit of measurement. Calories are used to measure the amount of energy that a food or beverage provides, as well as the amount of energy the body expends. Calories are essential to human health as the calories, or energy, we consume allow the body to function. Calories enable basic metabolic and cellular functions, including vital organ function, brain function, and digestion, as well as general daily movement and exercise.
According to the US dietary guidelines, the average adult male requires 2,500 calories per day, while the average adult female requires 2,000 calories per day (1). These values will vary from one individual to the next based on factors such as sex, height, age, body composition, exercise, and activity level.
Understanding Energy Balance
Given calories is another word for energy, energy balance is the balance of calories consumed compared to calories expended. Energy balance is the difference between calories “in” via food and beverage and calories “out” via the body’s daily energy requirements.
Calories in refers to the number of calories you get from the food you eat and beverages you drink.
Calories out refers to the number of calories your body burns, also known as your total daily energy expenditure (TDEE), which is composed of basal metabolic rate (BMR), thermic effect of food (TEF), exercise activity thermogenesis (EAT), and non-exercise activity thermogenesis (NEAT) (2). Total daily energy expenditure or TDEE is often referred to as the metabolism.
Your energy balance or the difference between calories in vs. calories out, which is defined by the laws of thermodynamics, determines whether body weight is lost, gained, or remains the same (3).
To maintain general health and stable weight, the energy we put into our bodies (calories in) must be the same as the energy we use through normal bodily functions and physical activity (calories out).
To gain weight, the energy we put into our bodies (calories in) must be greater than the energy we use through normal bodily functions and physical activity (calories out), also known as a calorie surplus.
To lose weight, the energy we put into our bodies (calories in) must be less than the energy we use through normal bodily functions and physical activity (calories out), also known as a calorie deficit.
What is a calorie deficit?
A calorie deficit occurs when you have a negative energy balance, which occurs when you take in fewer calories than you expend. Put simply, a calorie deficit is created when calories in are less than calories out.
Calories Deficit = Calories In < Calories Out
When you eat or drink, you put energy into your body. Your body then uses this energy to perform its daily functions required by your TDEE, and any excess energy is stored as glycogen or body fat to use later (4). By taking in fewer calories than your body needs and, therefore, creating a calorie deficit, your body will turn to stored energy, which is found in the form of body fat. As a result, you will lose weight.
How much of a calorie deficit do you need to lose weight?
As a rule of thumb, to lose one pound of fat you need to create a calorie deficit of approximately 3,500 calories (5). Meaning, to create one pound of fat loss your energy expenditure (calories out) must exceed the energy you consume via food and beverage (calories in) by 3,500 calories.
Given that the average adult male requires 2,500 calories per day and the adult female requires 2,000 calories per day, creating a 3,500-calorie deficit in one day is near impossible. Rather, a deficit of 3,500 calories to lose one pound of fat is accumulated over time by making smaller calorie deficit contributions. For example, if Jane Doe creates a deficit of 350 calories per day for 10 days, she would accumulate a calorie deficit of 3,500 calories and, ultimately, lose one pound of fat.
To be clear, the 3,500-calorie concept should be used as a rough guideline, mostly for the purposes of education, as it’s not a perfect science. Unfortunately, the mathematical model does not represent the metabolic adaptations that occur in a response to weight loss and how a deficit may need to be adjusted over time as body mass decreases and metabolic adaptation occurs (5).
However, while the “3,500 calorie deficit = 1 pound of fat loss” guideline is not a perfect mathematical equation, the law of thermodynamics still stands – a calorie deficit is required for weight loss. More energy must be expended than consumed for weight loss to occur, and the size of the deficit and the length of time it is maintained will determine how much weight is lost.
How big should my calorie deficit be?
A healthy deficit calorie can range anywhere from 10% – 30% of your total daily energy expenditure or TDEE. The smaller the deficit the slower fat loss will be and the larger the deficit the faster fat loss will be, however, bigger is not always better. The ideal deficit size is dependent upon the individual, the situation, and the goal.
Small Deficit: A small calorie deficit ranges between 10% – 15% below maintenance calories. A small deficit can be achieved with small changes, which typically feel less intrusive and easier to adhere to long term. It’s also less likely to have a counter-regulatory effect on metabolic rate and hinder athletic performance or training. However, given its small size, fat loss progress will be slower, and a higher degree of tracking precision is required as there are smaller margins for error.
Moderate Deficit: A moderate calorie deficit ranges between 20% – 25% below maintenance calories. A moderate deficit allows for more food flexibility and less tracking precision than a small deficit given it has larger margins for error. The larger deficit also allows for faster fat loss progress and, therefore, has a short diet timeline. However, it can feel more restrictive and is more likely to impact athletic performance and have a counter-regulatory response on metabolic rate.
Large Deficit: A large calorie deficit is 25% or more below maintenance calories. This deficit will yield the quickest results and is very useful for individuals with a limited time frame. However, it can feel very restrictive, as has very limited food flexibility, is most likely to induce intense feelings of hunger, and is far less sustainable and, therefore, has decreased long-term adherence. Additionally, a large deficit is very likely to negatively impact athletic performance and most likely to create a counter-regulatory response on metabolic rate, especially when followed long term.
Generally speaking, a small calorie deficit of 10-15% below maintenance calories is recommended as a starting deficit for the average person. While fat loss progress may be slower, it is far less restrictive, easier to adhere to, more sustainable long term, and least likely to create metabolic adaptations. When working towards a fat loss goal, it is best to start with the minimum calorie deficit required to achieve fat loss and increase as needed based on results.
How do I figure out my calorie deficit?
STEP 1: Determine your baseline daily calorie needs.
Before determining how many calories you need for weight loss or fat loss, determine your total daily calorie needs for general health and weight maintenance. Also known as your TDEE, this is the total number of calories you need to consume per day to maintain your current weight.
Your TDEE can be calculated using the Mifflin-St Jeor formula, which estimates your basal metabolic rate, and then adjusted based on activity level into account. This calculation considers your sex, age, height, weight, and activity level, and can be calculated by using an online calculator such as tdeecalculator.net. With that said, it’s important to note that this calculation is an estimate to help get you started, and adjustments may be required as you progress and/or metabolic adaptations occur.
STEP 2: Choose your calorie deficit size.
Once you’ve determined your TDEE, you can determine how big you want your calorie deficit to be. As noted, you do not need to create a big calorie deficit to lose weight; a deficit of 10%-15% is more than sufficient for sustainable weight loss and is much easier to maintain.
STEP 3: Calculate your daily calorie needs for fat loss.
Once you’ve determined the size of your deficit, you can determine your daily calorie needs for fat loss. This is done by multiplying your TDEE by your deficit percentage size and then subtracting the deficit from your TDEE.
- TDEE x % Calorie Deficit = Daily calorie deficit
- TDEE – Daily calorie deficit = Daily Calorie Needs for Fat Loss
Note: There are many online fat loss calorie calculators and apps that will do this calculation for you, this is simply an explanation of how the calculation is done.
STEP 4: Consider your macros (optional but beneficial).
When it comes to fat loss, a calorie deficit is the only essential requirement, however, considering macronutrient balance can be helpful. Also known as macros, the balance of protein, carbohydrates, and fats you consume can have an impact on your satiety levels and changes in body composition, specifically muscle mass. Generally speaking, consuming adequate protein can help to ensure you are maintaining lean muscle mass during fat loss phases, while consuming adequate protein and fiber can help to increase satiety signals and limit feelings of extreme hunger while in a calorie deficit.
Calorie Deficit Example
Here is an example of how to calculate a calorie deficit for the average adult American female (6).
Jane Doe’s goal is to lose fat and her details are as follows:
- Sex: Female
- Age: 40
- Height: 5’4
- Weight: 171 pounds
- Lifestyle: Office job
- Activity Level: Moderate (3 x 45-minute HITT classes per week, 1 x 60-minute yoga class per week, 7 x 20-minute dog walk per day)
Based on Jane’s details and using an online calculator, her total daily energy expenditure (“calories out” per day) is estimated at:
TDEE = 2,217 calories
Given her goal is fat loss and she wants to do so in a sustainable way, it would be recommended that Jane select a fat loss deficit in the range of 10% – 15%, in which case, Jane has chosen to begin with a calorie deficit of 15%. Therefore, her recommended starting calorie intake for her fat loss goal would be:
TDEE x % Calorie Deficit = Daily calorie deficit
2,217 x 15% = 333 calories
TDEE – Daily calorie deficit = Daily Calorie Needs for Fat Loss
2,217 – 333 = 1,884 calories per day
Therefore, it would be recommended that Jane eat to a calorie target of 1,884 calories per day, providing her with an estimated calorie deficit of 333 calories per day, which would support a fat loss rate of roughly 1 pound of fat loss every 10-11 days (3,500 calories ÷ 333 calories/day = 10.51 days).
As Jane progresses, she can adjust her calorie deficit and daily calorie intake as needed based on her results by checking in every couple of weeks. For instance, if after 2 weeks she:
- Gained weight, looks, or feels bigger, she could reduce her calories by an additional 5% – 10%.
- Sees no change in weight or feels the same, she could reduce her calories by an additional 5%.
- Lost weight and feels better, she can keep her calories the same.
This process of consistently checking in and analyzing her progress will allow her to make result-based decisions to support her goals.
Furthermore, if Jane wanted to increase her fat loss rate or take a more “aggressive” approach toward her fat loss goal, she could recalculate her caloric intake with a larger deficit, such as 20% or 25%, based on her same TDEE or new TDEE should she have lost weight.
How To Start a Calorie Deficit
While the math of calculating a calorie deficit may seem simple in theory, the act of implementing it in real life can seem a little more daunting. So, here are some simple steps on how to start a calorie deficit.
- Calculate your calorie target. The first step is to determine your calorie deficit to determine your daily calorie target. This can be done using the methodology shared above or by using a calorie deficit calculator.
- Use a tracking app. Once you’ve determined your calorie target, use an app to track your calorie intake. Calorie-tracking apps, such as MyFitnessPal or FatSecret are designed to help you track your calorie intake without doing complicated math. Please note, to ensure that your calorie tracking is accurate, you must weigh and/or measure your food. Unfortunately, it is almost impossible to accurately estimate food intake, therefore, weighing food portions is the only way to accurately track your calorie intake.
- Be consistent. Consistency is king when it comes to a calorie deficit. Remember, fat loss occurs because of consistent calorie deficit contributions over the course of multiple days and weeks. For fat loss to occur, you need to remain in a calorie deficit consistently. If you’re in a calorie deficit for 3 days, in a surplus for 4 days, then back in a deficit for 2 days, then at maintenance for 2 days, and back in a surplus for 1 day, etc., it’s going to impede your progress and cause fat loss to take longer or not occur at all.
- Check in and adjust as needed. As you progress, be sure to check in and adjust your calorie intake as needed based on your results. It’s important to keep in mind that calorie calculations are all estimates. Your body is the best coach you will ever have, so it’s important that you pay attention to it. Whether you’re losing weight too slowly, too quickly (yes, this can happen!), or not losing weight at all, weighing yourself and taking measurements of yourself regularly will allow you to make informed decisions and adjustments.
- Prioritize exercise. In addition to controlling your food intake, it’s important that you prioritize exercise and activity to support a fat loss goal. Not only does exercise help to increase energy expenditure (calories out) but certain forms of activity, namely resistance training, can help to reduce the risk of muscle loss during a calorie deficit.
If you want support with creating a calorie deficit, it is best to work with a registered dietician or qualified coach to ensure that you are taking the best approach for your health and goals.
Can you create a calorie deficit without tracking calories?
While a calorie deficit is the one and only requirement for fat loss to occur, it is possible to create a calorie deficit without tracking calories. There are different strategies and lifestyle changes that you can implement into your daily routine to help ensure that you are creating a calorie deficit without tracking, weighing, or measuring food.
To use a financial analogy, if your goal is to save money, it is imperative that you ensure that you are making more money (“money in”) than you are spending (“money out”). One could argue that the most strategic approach to saving money would be to create a detailed budget and track every dollar you spend; if you earn $4,000 per month and budget to only spend $3,000 per month, you will save $1,000 per month.
However, one could also argue that focusing on changing your spending behaviors, without creating a detailed budget, could also help you save money. For example, if you only buy the groceries you absolutely need, stop dining out, cancel unnecessary subscriptions, refrain from buying new clothes, and only spend money on essentials, you could alter your spending behaviors in a way that would help you to save money. While these behavior changes are not as precise as a detailed budget or guarantee that you will save money, if designed strategically and implemented consistently, they have the potential to be great tools for saving money.
So, the same concept can be applied to fat loss. While tracking calories is arguably the most strategic and effective method for creating a calorie deficit, you can create one by simply adjusting food behaviors. From monitoring portion sizes to limiting liquid calories, creating balanced meals with protein and vegetables, increasing exercise, and limiting snacking, there are many different ways to restrict calorie intake and increase calorie expenditure to create a calorie deficit without counting calories.
Calorie Deficit FAQs
Here are some of the most asked calorie deficit questions:
When used appropriately, a calorie deficit is a safe tool for weight loss. While it is not recommended that individuals remain in a calorie deficit for extended periods of time or use calorie deficits that are overly aggressive, using a small to moderate calorie deficit for the purpose of fat loss in an otherwise healthy individual is safe.
A 500 calorie deficit means that the individual is consuming 500 calories less than they are expending per day or that “calories out” exceed “calories in” by 500 calories. For example, if someone expends 2,200 calories in a day but only consumes 1,700 calories, they have created a calorie deficit of 500 calories.
Given that 1 pound of fat loss is equivalent to roughly 3,500 calories, to lose 1 pound of fat per week one would need to consume create a calorie deficit of 500 calories per day (-500 calories per day x 7 days of the week = -3,500 calories per week).
When it comes to calorie intake, “enough” calories depends on the individual (sex, age, height, weight, and activity level) and their personal goals. In most cases, 1,500 calories will create a calorie deficit, however, it may be too restrictive and unsustainable to maintain. Moreover, 1,500 calories may be a more aggressive deficit approach for some and, therefore, has the potential to down-regulate metabolic rate more quickly.
In most cases, a calorie intake of 1,200 calories per day would create a calorie deficit, given that the average adult female requires 2,000 calories per day and the average adult male requires 2,500 calories per day. While this very large calorie deficit can help some people lose fat quickly in the short term, it is unsustainable and likely to have negative metabolic adaptations and hormonal side effects in the long run and is, therefore, not recommended.
The most obvious sign that you are in a calorie is weight loss. If you’re weighing yourself and the numbers are going down, it’s the best sign you are in a calorie deficit. While it is normal to see scale fluctuations from one day to the next (i.e., weight loss vs. fat loss), a pattern of weight loss over the course of long periods of time is an indication that you are in a calorie deficit. In addition to decreases in weight, decreases in measurements (i.e., inches of hips, bust, and waist) and clothes fitting looser are also typically indications that you are in a calorie deficit, as there are situations when fat loss can occur without changes in the scale.
While it is normal to feel hungry at times during a calorie deficit, you are consuming fewer calories than you are expending after all, the intensity of your hunger is highly impacted by the size of the calorie deficit created. Larger deficits have greater potential to increase hunger, while smaller deficits tend to be easier to adhere to as the hunger signals are far less noticeable.
Put simply, if you’re not losing weight, you’re not in a calorie deficit. This can occur for several reasons; inaccurate calorie calculations, inaccurate tracking, lack of consistency, metabolic adaptation, etc. While there are cases where individuals eat in a calorie deficit and are unable to lose weight and medical intervention is required, this is limited to a small segment of the population.
While a calorie deficit is the only requirement for weight loss and fat loss, the ratio of macronutrients, or “macros”, consumed can be very helpful for satiety signals, as well as body composition. Consuming adequate protein, carbohydrates, and fats will help to ensure that you are promoting overall health and your body is functionally optimally. Moreover, consuming adequate protein and fiber can help to promote feelings of fullness, which makes sticking to a calorie deficit much easier, and consuming adequate protein will help to reduce the loss of lean muscle mass.
Tips for Sticking to a Calorie Deficit
Prioritize whole foods. Consuming a diet primarily composed of whole foods can help to ensure that you are consuming foods that are highly satiating and rich in nutrients. Whole foods, such as whole grains, fruits, vegetables, lean meats, seafood, eggs, dairy products, legumes, nuts, and seeds, are much richer in vitamins, minerals, protein, and fiber than processed foods and contain far less sugar, oil, and, therefore, calories. Not only do many forms of highly processed foods have a much higher calorie density than whole foods, but they are engineered to be hyper-palatable, which can lead you to eat far more foods and calories in one sitting. Prioritizing whole foods in the diet, at least most of the time, can help to increase nutrient consumption and satiety levels, and control calories at the same time.
Limit liquid calories. Liquid calories, such as juice, sodas, energy drinks, or alcohol, do not hold strong satiety properties or suppress hunger as quickly as calories whole from foods. While not all liquid calories are not inherently unhealthy or fattening, especially beverages like smoothies, juice, and milk, their limited impact on hunger signals makes it easier to consume large amounts of calories and still be hungry, making it more difficult to maintain a calorie deficit (7). For this reason, when trying to eat in a calorie deficit, it is best to prioritize consuming calories from solid foods as opposed to liquids or beverages.
Prioritize protein and fiber. Including a portion of protein and fiber in all your meals can make sticking to a calorie deficit much easier since protein is the most satiating macronutrient and fiber helps to increase feelings of fullness. A higher protein intake has been linked with feelings of fullness, while dietary fiber is known to be associated with improved satiation, satiety, and reduced food intake (8)(9).
Plan ahead. Planning your meals in advance can help save you time, improve your food choices, and help ensure that you are sticking to a calorie deficit. By planning your meals in advance, you are better able to ensure that your meals will support your calorie deficit. By mapping out your meals and calculating your calories before your day beings you will take a lot of guesswork out of the process and reduce stress around mealtime at the same time.
Get good sleep and manage stress. Sleep quality and stress levels can influence adherence to a calorie deficit as they affect your hunger hormones and can increase food cravings. Our hunger hormones, ghrelin and leptin, help to regulate our appetite; ghrelin signals your brain when you’re hungry and leptin lets your brain know when you have enough energy stored and feel full. Poor sleep or lack of sleep has been shown to increase ghrelin and decrease leptin, which can lead to an increased appetite and a higher daily calorie intake (10)(11)(12). Therefore, managing stress levels and getting good sleep can help to support weight loss.
Don’t stress over scale fluctuations. As you work towards a fat loss goal, it’s important to keep in mind that there is a difference between fat loss and weight loss and that daily scale fluctuations are completely normal. A person’s weight measurement accounts for fat-free body mass (bone, organs, muscle, water) and fat mass (essential and non-essential), and fluctuations in water intake, sodium intake, food intake, and digestion can all impact weight from one day to the next. Therefore, fluctuations on the scale are not always reflections of fat loss or gain, they are often reflections of changes in weight, which doesn’t always represent fat. Instead of worrying about daily fluctuations from one day to the next, pay attention to long-term trends across weeks and months, as this is a much better representation of whether you are in a calorie deficit.
The Bottom Line
Creating a calorie deficit is essential for fat loss and occurs when you have a negative energy balance; calories consumed are less than calories expended. Although the advice to “eat fewer calories and burn more calories” is correct, understanding exactly how many calories to consume for your personal situation and goal can make sustainable and healthy weight loss much more achievable. While it is possible to calculate a calorie deficit using a formula or online calorie calculator, if you are confused or overwhelmed it is best to work with a registered dietitian or qualified nutritionist who can help determine the calorie deficit and approach that is best for you.
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