What Is A Calorie Deficit? (Explained Simply For Busy Professionals)

A calorie deficit is when you consume fewer calories than your body needs in an effort to lose weight.

There are many ways to create a calorie deficit, and the best method depends on your individual goals and lifestyle.

However, it’s important to note that not all calorie deficits are created equal. If done incorrectly, a calorie deficit can lead to a loss of muscle mass.

Keep reading to learn how to do it safely.

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What Is a Caloric Deficit?

A calorie deficit is when you consume fewer calories than your body needs to do all of its normal functions. Everyone must eat a certain number of maintenance calories daily to maintain their body in homeostasis.

Therefore, when you create a calorie deficit, your body has to find a way to make up for the lack of energy that it’s not getting from food. In other words, your body is forced to tap into other forms of energy, like stored fat, to make up the difference.

As such, a calorie deficit will result in weight loss.

How Much of a Calorie Deficit Do You Need to Lose Weight?

A general rule is that one pound of fat equals about 3,500 calories. Therefore, if you want to lose one pound per week, you need to create a daily deficit of ~500 calories.

In this example, you could eliminate 250 calories from your diet and burn 250 extra calories through exercise.

However, this amount of calories might be too high or too low for you.

The size of your calorie deficit depends on various factors, including your age, current weight, activity level, and muscle mass.

For most people, I recommend starting with a small deficit of about 250-300 calories daily. It’s essential to create a sustainable calorie deficit – one that you can stick to long-term – to see lasting results.

How to Figure Out a Good Calorie Deficit (Using BMR)

The simplest method to figure out a reasonable calorie deficit is to calculate your estimated basal metabolic rate (BMR).

Your BMR is the minimum number of calories your body needs to keep all of its systems functioning properly. In other words, it’s the number of calories that you would burn if you were to do nothing but rest all day.

Step 1: Calculate Your BMR

Your basal metabolic rate is the number of calories your body burns at rest to keep your basic functions working.

Here is the formula for calculating a rough estimate of your BMR.

  • For women it is: 655 + ( 4.35 x weight in pounds ) + ( 4.7 x height in inches) – ( 4.7 x age in years )
  • For Men it is : 66 + ( 6.23 x weight in pounds ) + ( 12.7 x height in inches ) – ( 6.8 x age in years )

Or, you can just use the calculator below in the next section.

Step 2: Determine Your TDEE

After calculating your basal metabolic rate, you need to multiply it by a number reflecting your physical activity level.

  • If you lead a sedentary lifestyle (little to no exercise): BMR x 1.2
  • If you are lightly active (light exercise/sports 1-3 days per week): BMR x 1.35
  • If you are moderately active (moderate exercise 3-5 days per week): BMR x 1.5
  • If you are very active (hard exercise 5-6 days per week): BMR x 1.75
  • If you train like Michael Phelps (strenuous exercise daily): BMR x 2.
Activity LevelMultiplication Factor
SedentaryMultiply your BMR by 1.2
Mildly ActiveMultiply your BMR by 1.35
Moderately ActiveMultiply your BMR by 1.5
Very ActiveMultiply your BMR by 1.75
Michael PhelpsMultiply your BMR by 2

The number you get reflects your total daily energy expenditure (TDEE) – or the total number of calories you burn daily.

Step 3: Determine Your Daily Calories For Fat Loss

Now that you know your TDEE, you can create a calorie deficit by subtracting 250-300 calories from that number.

For example: If your TDEE is 2,500 calories, a reasonable calorie deficit would be 2,200.

Calorie Deficit Calculator

For convenience, here is a simple calculator to help determine your BMR and calorie deficit.

For this calculator, enter your goal weight and the time frame you want to achieve it.

What Is an Unhealthy Calorie Deficit?

An unhealthy calorie deficit is one that is too large and not sustainable long term.

A good rule of thumb is to never go below 1,200 calories per day. In addition, you should aim to lose no more than 1-1.5% of your body weight per week.

For example, if you weigh 200 pounds, you should aim to lose no more than 2-3 pounds per week.

Anything more than that, and you run the risk of experiencing the adverse side effects of rapid weight loss, such as:

  • Muscle Loss
  • Fatigue
  • Hormone Imbalances
  • Irritability
  • Constantly Feeling Hungry
  • Difficulty Sleeping
  • and Slower Metabolism

I go over how to lose weight without losing muscle here.

Will It Slow My Metabolism?

Yes, calorie deficits will slow down your metabolism. When you cut calories, your body responds by burning fewer calories to conserve energy.

This is called “adaptive thermogenesis,” one of the ways your body protects itself from starvation. 

In addition, the more weight you lose, the lower your calorie needs will be due to the loss of lean body mass. In other words, your body is physically smaller and requires fewer calories to maintain itself.

Fortunately, you can do a few things to offset the metabolic slowdown that occurs with weight loss.

How To Offset The Negative Effects of a Calorie Deficit

Here are three things you can do to counteract the metabolic slowdown with weight loss.

Do Resistance Training Regularly:

One of the best things you can do to offset the metabolic slowdown that comes with a calorie deficit is to lift weights regularly.

When you exercise, you signal to your body that it needs to maintain or grow your muscle tissue, despite being in a calorie deficit. In addition, the more lean muscle mass you have, the higher your resting metabolic rate will be.

Lift weights (or do calisthenics) at least three times per week to see the best results.

Eat Enough Protein

Believe it or not, you burn calories digesting food. This is called the thermic effect of food, accounting for 10% of your daily calorie expenditure.

Interestingly, protein has the highest thermic effect of any macronutrient, which means you burn more calories digesting protein than fat or carbs.

Protein has a thermic effect of 20-35%, meaning 20-35% of the calories you eat from protein will be burned off just by digesting and metabolizing it.

Protein is also necessary to maintain and grow muscle tissue.

A good rule of thumb is to consume at least 0.7 grams of protein per pound of body weight every day. 

Get Enough Sleep

Sleep is such a critical aspect of health. Not only does it help to improve your mental and emotional well-being, but it also has a direct impact on your physical health.

Sleep deprivation can lead to many problems, including weight gain, decreased muscle mass, and a slower metabolism– not a good combination in the face of calorie restriction.

Aim to get at least 7 hours of sleep every night for the best results.

Other Related Questions

Are 1500 Calories a Day Enough?

Depending on your weight, height, and activity level, 1500 calories per day may be enough to achieve healthy weight loss. However, it’s always best to use a BMR calculator to get a rough estimate of your caloric needs.

The goal is to eat enough calories to support your weight loss goals without dipping too low and putting your health at risk.

Are Calorie Deficits Different for Women?

Calorie deficits work very similarly between men and women, but there are some subtle differences. In general, women require fewer calories than men to maintain their weight.

The reason is that women tend to have less muscle mass than men and have higher body fat levels. As a result, women may need to eat slightly fewer calories than men to lose weight at the same rate.

Nonetheless, your weight and activity level will always influence the number of calories you need to eat to lose fat.

My Preferred Way of Creating A Healthy Calorie Deficit

In my opinion, the best way to create a deficit and achieve sustainable weight loss is by increasing the quality of the foods you eat.

In other words, it is much easier to focus on ADDING nutrient-dense foods that are high in vitamins, minerals, and fiber into your diet rather than TAKING AWAY junk food that tend to be full of excess calories.

This approach works because these foods satiate and keep your appetite in check, despite being low in calories. As such, they help to crowd out unhealthy foods while still allowing you to eat enough calories to support your weight loss goals.

In addition, by eating more nutrient-dense foods, you will naturally consume fewer calories without consciously restricting yourself.

Some of the best nutrient-dense whole foods that you can add to your diet include:

  • Lean proteins like chicken, fish, tofu, and tempeh
  • Vegetables like leafy greens
  • Fruits
  • Healthy fats like nuts and seeds

We have even put together a step-by-step nutrition program to help you consume as many of these nutrient-dense foods as possible without counting calories. It’s called The Compound Diet.


The Bottom Line

Calorie deficits are necessary for weight loss, but you must do it in a calculated and healthy way.

Cutting calories too drastically can lead to unwanted side effects such as muscle loss, fatigue, and a slower metabolism.

To avoid these problems, ensure you are eating enough protein and getting enough sleep. In addition, try to do resistance training 3-4 times per week to offset the adverse effects of caloric restriction.

Now I want to hear from you.

Have you tried a calorie deficit before?

Let me know in the comments below.

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Alex Robles, MD, CPT / Brittany Robles, MD, MPH, CPT

Alex & Brittany Robles are physicians, NASM Certified Personal Trainers, and founders of The White Coat Trainer: a resource dedicated to improving the health and fitness of busy professionals using time-efficient strategies. Their advice has been featured in My Fitness Pal, Prevention, Livestrong, Reader’s Digest, Bustle, The Active Times, and more. Learn more about them here.


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