Calorie Deficit – How Does it Work and What You Need to Know


Calorie Deficit – How Does it Work and What You Need to Know

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Calories – in other words, the stock of energy taken from edible resources stored in our body – is what everyone needs daily. But they are not equal for everyone.

It is the same for the calorie deficit. This lack of calories is required to achieve an individual’s target of energy units or weight.

It is brought about by either altering different elements of one’s meals or adjusting the amount of one’s workout(s).

If we come to discuss two persons having an equal amount of carbs, though, we would notice close amounts of calories spent, however different the number of weekly calories has been taken in.

Here’s a video on calorie deficit from James Smith, popular online personal trainer, explains. There are several factors to consider when applying a calorie deficit to our diet.

Different needs for different goals

Before moving to deficits, you should know how much food content you should retain for effective body development. It consists of the following nutrients:

Macronutrients (macros): Proteins, carbohydrates, and fats
These are required in relatively large amounts daily to provide your body with energy (in calories) and promote cellular growth, immune function, and overall repair.
Micronutrients: vitamins and minerals
These, taken in smaller amounts, regulate body systems, and maintain the good function of organs.

It is important to balance macronutrients for optimal health and wellness.

Combining proteins, carbs, and healthy fats in your meal can be easy, but knowing the respective proportions won’t be so.

Since everybody needs a different requirement ratio, you should first make sure you have enough macros within their ranges to balance your macros.

Athletes track macros instead of calories to achieve a fitness or performance goal. Similar is the case of medical patients, like type 2 diabetes who keep a watch on their carb intake.

It is more complex than with calories since 3 numbers are involved under management.

However, it becomes easier and safer if higher protein intake helps to eat less to lose weight or a controlled intake of saturated fat helps lower the risks for a heart patient.

The No. 1 Sunday Times Best Selling Author⁣, James Smith, provides you with his own macro calculator where you can set your training goal, biometrics, and activity level to determine your daily calorie and protein targets.

Tracking calories is simpler and quicker. It helps manage your weight, with a considerable calorie deficit taken regularly.

You can lose or maintain weight by looking into Nutrition Facts labels or online nutrition databases.

How calorie deficit works for you

A calorie deficit is generally required to lose weight, which works by burning more calories than you eat or drink.

That of 500 cal per day is enough for most people’s weight loss, not affecting hunger or energy levels.

On the other hand, the daily calories burnt is known as calorie expenditure and comprises of:

  • Resting energy expenditure (REE)
    Calories you use at rest for vital functions (breathing and blood circulation)
  • Thermic effect of food
    Calories you spend on digesting, absorbing, and metabolizing food
  • Activity energy expenditure
    Calories you burn during sports like exercise/non-exercise related activities (fidgeting, household chores)

In contrast, if your body gains more calories than it spends, you will be in a calorie surplus instead. This way, a sedentary lifestyle can eventually make you an obese person.

Even with hardly any physical activity, you might be spending calories.

Those would be the first two parts of calorie expenditure, which keep up your basic bodily functions, known as the basal metabolic rate (BMR), aka resting metabolic rate (RMR).

These are what I call your couch-potato calories. Sari Greaves
dietitian, RD, CDN (SAWLC, Bedminster, NJ), spokesperson (ADA) -

Your BMR can assist you in reaching your goals, whereby you can:

  • Work out a more effective strategy to lose weight.
  • Keep a better track of your calorie count.
  • Understand better how exercise affects your waistline.
  • Adjust calorie intake of diets following personal guidelines for weight loss

You can consider an online calculator to find out your BMR by inputting relevant physical information, or calculate it yourself using equations as shown below.

  • Men: BMR = 66 + (weight in pounds x 6.23) + (height in inches x 12.7) – (age in years x 6.8)
  • Women: BMR = 655 + (weight in pounds x 4.35) + (height in inches x 4.7) – (age in years x 4.7)

Your daily caloric needs become the result above multiplied by your activity level for a specific exercise frequency, as shown below:

  • Rarely = BMR x 1.2
  • 1-2 days/week = BMR x 1.375
  • 3-5 days/week = BMR x 1.55
  • 6-7 days/week = BMR x 1.725
  • Everyday or twice everyday or commuting for job = BMR x 1.9

The resulting number of calories will be that you spend days without any workout or deficit at a constant weight.

Then, you can achieve a better weight loss by reducing that daily caloric-intake and planning for higher physical activity.

To go on a calorie deficit using BMR, you just have to take off 500 cal from your daily diet to lose 1 pound each week, as per Greaves.

Your BMR is not discouraged from an influence where you get to burn more calories. You can opt for a more vigorous physical activity through:

  • Aerobic exercise
    You receive a temporary boost to your BMR (shown by an after-burn or excess oxygen consumption after exercise), which drops significantly after the workout, with your BMR reverting back within 15 min to 48 hours.
  • Strength training
    You gain a more durable BMR boost with modified body composition.
    Since muscles burn more calories than fats when inactive, a higher muscle mass like in men leads to a naturally agreeable higher BMR.
  • Higher calorie deficit
    With more exercise, you can burn a few more calories on top of your calorie deficit, to give you a proportional weight loss.

Also, a higher workout intensity can help you similarly for weight loss.

Otherwise, to generally find your calorie deficit, you need an idea of your maintenance calories, that is, calories required to support energy expenditure.

For that, you have calorie calculators like the NIH Body Weight Planner, which uses information like your weight, sex, age, height, and physical activity level.

You can also choose to get a more precise number if you track your calorie intake and weight daily for 10 days.

A calorie tracking app might come handy on a constant level of daily activity, with the same scale, time, and clothes for better accuracy despite the fluctuating weight.

Then, calculate the average calorie intake for these 10 days and subtract 500 from it to get your new daily calorie goal.

You will find your maintenance calories decreasing with weight over time. So, proper daily calorie intake must be followed as per your weight loss goals.

The minimum should be 1.2kcal for women and 1.5kcal for men, to guarantee a healthy and effective program.

Measures when calorie deficit doesn’t work

It is necessary to know when to start a calorie deficit. Firstly, you should be aware of your optimal weight for your age.

If you’re underweight, a weight gain through additional calories is recommended. If within the optimum range, you just need to maintain your caloric intake.

If beyond that range, then it’s time to cut on fats and carbs.

The caloric deficit should be maintained throughout your cycle, as your BMR will not sustain an on and off deficit, nor does it work identically for everyone.

When your body goes through starvation, your metabolism slows down for energy conservation, making it worse than that prior to the cycle.

Consequently, returning to your maintenance intake will regress your weight loss.

That is why your total calorie intake should be maintained at or above your BMR, especially when shedding the last pounds.

Excessive cardio exercise can similarly affect you.

To avoid a crashing diet and obtain quick results, you should maintain a viable and consistent deficit which will last for weeks. Simply use your BMR to find it.

Most importantly, whatever you might be losing should be fat and not any scale weight. So your weight scale won’t really help you here.

If you want to lose fat, place your focus on body composition, specifically fat to muscle ratio.

Know that 500cal. deficit per day (3.5kcal per week) can cause a loss of either 1 lb of fat or that of nearly 6 lbs of muscle.

Therefore, to avoid any undesirable calorie deficit muscle loss, you must pay attention to a correct deficit based on your current fat percentage and activity level.

Much body fat will work with large deficits, but a lean body requires a revised intake to keep up the lean tissue.

Hence, it becomes tough to shed the last pounds to get a ripped physique.

However, having a calorie deficit when cutting down on fats is not merely to retreat on the fat intake.

Even when the energy density of fats is more than double that of carbs or proteins of the same weight.

A review on weight loss and energy expenditure showed that high protein/low carb diets contributed to a 5.5 lbs greater weight loss than high-carb/low-fat diets.

Still, neither those macros nor the energy changes were able to justify the differences in weight loss.

If we speak of glycemic carbs, low ones ease the loss of glycogen stores (our energy reserve) as much as 4.4 lbs with longer digestion.

So its overconsumption is not a problem. It is clearer knowing that protein has the highest thermic effect, requiring the most metabolic energy.

That means higher energy expenditure, and hence more burnt calories ensuring better long-term weight loss.

High glycemic carbs contrastingly release insulin with a large, rapid rise and drop in blood sugar through quick digestion, leaving you hungry by expanding your fat stores.

They make up highly processed foods and need to be balanced in food combinations.

For those reasons, taking moderate and high glycemic foods are advised during and after exercise, for muscle recovery and replenishment.

Then, insulin is secreted to break and carry proteins with better blood flow to the muscles.

Therefore, you should plan a proper diet composition since size deficits affect your body.

Apart from that, your goals, preferences, and tolerances have their roles to play. These make the deficits extremely different for any two individuals.

Speaking of that, when is a calorie deficit too big?

First, get to know your maintenance calories. Then, subtract a specific percentage from it to make out the respective deficit, as stated below:

  • Small: ≤15%
  • Medium: 15-25%
  • Large: ≥25%

While smaller deficits show fewer changes, positive and negative, larger deficits show the opposite. Do keep track of your caloric deficit to ensure you lose the required fat.

Alternatively, you can choose not to if you are convinced that calorie counting does not work.

That can be either by inaccurate portion estimates, wrong food calorie counts, inaccurate exercise calorie burns, or unreliable BMR.

Then only healthy nutrition and vigorous exercises count. For a flexible nutrition plan and shorter exercise duration, you can enter an Athlean-X calorie deficit.

How to go on a calorie deficit?

Should you need one in your diet, know that it varies with different factors, like your weight, calorie needs, training intensity, and weight loss goals.

As you agree to patiently progress your way to a more toned body, you can use large and small deficits as per your goals.

Once you know their pros and cons, you can apply them to your diet.

Small Deficit

Already fit persons (<15% bf for men, <21% for women) use this deficit to get a ripped body under 12% body fat.

Here, a 0.5-1 lb fat loss per week is recommended for lean bodies, and not starvation mode. It requires abstaining from high caloric/glycemic foods.

  • Eases dieting, requiring fewer changes in lifestyle
  • Many dieters are no more hungry
  • Takes in people with the anxiety of dieting easily
  • Displays no energy loss, mood problem, or decline in activity level or metabolic rate.
  • Maintains performance/recovery with intensity and volume, though slightly harder training
  • Guaranteed muscle retention for lean people, with weightlifting and enough protein
  • Possibly longer adherence with patience and consistency
  • Drastic falling rate of fat loss, requiring longer diet and showing visible changes after weeks
  • Need of patience and persistence
  • Requires meticulous application of caloric deficit, with a low error margin of food intake
  • Not imposing for a commitment, although a great option

Medium deficit

A challenge for the average people (14 – 24% bf for men, 21 – 31% bf for women) with gym experience and a manageable 500cal day deficit for fat loss and an upgraded fitness level.

With 1 pound less fat each week, 8 lbs fat loss (4.2% bf) can be feasible in two months alongside some abdominal work, which makes this a safe/great deficit.

  • Brings strong, immediate, durable satisfaction with often a nice, encouraging 1-2 lbs weekly fat loss
  • Makes one partially hungry, but also usually able to cope with
  • May bring down training progress to a halt, but rarely to a reversion
  • Usually slower but not awful recovery after workouts
  • Enables continuous training for a deficit by diet and exercise
  • Sure muscle retention for overweight or average people
  • No inclination towards mood problems, low energy levels or metabolic slowdown
  • Bigger potential of lean people to lose strength and muscle even with strength training and proper protein intake
  • Liability of poor performance for high-level athletes
  • Bland choice due to common use
  • Slower fat loss than large deficits
  • Corruptible without assiduity to diet due to lower error margin with restricted calories
  • Holds back certain people

Large deficit

This applies to the most obese persons with a lot of body fat to lose (>25% for men, >32% for women).

With this deficit, you enter a starvation mode to lose water weight or muscle mass for a possible 2-pound weight loss per week.

But the corresponding 1 kcal/day deficit will drag you under your BMR, and hence thwart your goals.

  • Fastest loss of fat in weeks
  • Gives great prompt satisfaction, promoting long-term adherence to weight loss with a motivation boost to diet
  • Encourages less overeating with larger error margin on a monitored calorie intake
  • Ruins exercise performance of high intensity/volume, with poor training and a higher risk of illness/injury
  • Obliges low consumption, forcing dieters to pick low-calorie diet over much exercise
  • Holds back some people, compromising their adherence
  • Necessitates extreme abstinence and food restriction with possible eating disorder symptoms (hardly anything more than your protein intake)
  • Higher risk of nutrient deficiencies on a longer duration
  • The most to cause significant muscle loss, especially in lean people, making it suitable for very overweight people with strength training and enough protein
  • Makes greater falls in non-exercise movements and resting metabolic rates
  • Highly disappointing without correct crash diet setup and desired results
  • Cuts down long term slimming habits

If you select a calorie deficit, it doesn’t mean you have to use it for your entire diet. You could also establish different approaches to attain your goals. For example, you can:

  • Begin with a larger deficit, shifting gradually to a smaller deficit.
  • Begin with a smaller deficit, shifting gradually to a larger deficit.
  • Decide the periods where you eat large deficits and small deficits.
  • Use a size deficit that conforms to your lifestyle at the time.
    If you’re busy with short breaks, use a larger deficit. If you’re in holidays among lots of food, use a smaller deficit.

With those in mind, your next query will be – “what should my calorie deficit be?”.

Setting a Caloric Deficit

When dieting, you will find it tough yet important to plan a good approach with correct deficits. Here are 4 such methods you can adopt to achieve fat loss.

  1. Target rate of fat loss

    The most common technique is through a specific rate usually decided about 1 pound per week.

    If 1 lb of fat can contain 3.5kcal, you will reduce your daily calorie intake by 500 cal. This works well for most people since it is approachable.

    However, this size deficit may prove to be tough for some and slow for others.

    If your daily maintenance is 2kcal, it will be reasonable to deduct less than 25% (i.e., 500cal) from your diet.

    If you maintain your intake at 4kcal per day, then you can contemplate a larger deficit for a faster rate of fat loss.

  2. Take calories as per body weight

    Here, you will instead set your calorie intake with an already decided fat loss beforehand.

    This method will suit your individual needs as it justifies differences in body size.

    Nevertheless, your body weight doesn’t say much about your total energy needs.

    This way of setting your calorie intake along with higher energy needs due to much exercise can result in an excessive deficit.

    Bodybuilders often start with a 10-12 calorie intake per pound of weight.

    However, within their guidelines, endurance sportspersons could be burning over twice the number of calories they take daily.

    In contrast, sedentary people with less significant calorie needs will find this deficit too small concerning their goals.

  3. Cut a maximum of calories

    With this method, your concern is simply to eat as less as possible, where your daily calorie intake becomes your least but essential amount of food.

    However, it is not a great option since it discourages most people’s estimation of their calorie intake, thereby being unable to establish their calorie needs.

    Your calorie intake will also be hard to adjust as you diet.

    Large deficits might often be bad; besides, eating the least possible won’t be an optimal guide to set your calorie intake.

  4. Take out a percentage of calories from your maintenance intake

    Generally, the best approach to make out your calorie deficit is to take off a reasonable percentage of calories (<25%) from what you need daily to maintain your body weight.

    This way, your calorie intake meets your energy needs instead of a target number to reach a fat loss rate.

    Having higher energy needs will make you eat more in proportions and lose fat, whereas lower energy needs will create an appropriate deficit for your calorie intake.

Switching to keto diets

Creating a calorie deficit with a ketogenic diet causes a state of calorie-deficit ketosis, implying elevated blood levels of ketones.

That happens due to carbohydrate inhibition, which brings the body to burn fat and hence, produces ketone bodies.

Ketogenic diets are better used for long-term weight loss and many other health-related conditions.

They have shown greater body weight loss than those in classic low-fat diets in a meta-analysis.

Weight loss on a diet of 15 days involved loss of glycogen stored in body water. While the weight loss came from fat, the fat-free mass was preserved.

It is also shown that diets restricting carbs led to a lower, constant body fat mass, or even higher, lean body mass.

While other diets restricting calories in the long term can leave dieters hungry and unsatisfied, keto diets satiate them with the essential fats and proteins instead of carbs.

You can confirm this by comparing cereals only with a protein and fat-rich meal.

During ketosis exclusively, your hunger hormone is suppressed, leaving you easily full. So, it is clear to us who will win the ketosis vs. calorie deficit battle.

On such diet, your body can burn fat at more than double the rate. Low insulin levels help break fats into their acids besides restricting fat storage.

To preserve lean body (muscle) mass, you will require more calories through a low-carb/high-protein intake, which also favor a higher BMR.

So neither is calorie deficit important in keto nor is it any better.

Nevertheless, you should be careful with keto foods as they are high in calories for a low physical volume.

Potentially overdoing your protein and fat intake can result in increased calorie consumption.

Some common keto-approved foods you should refrain from are cheese, butter, cream, coconut oil, among others.

Therefore it becomes exigent to track your calories. Many people follow their hunger for better control. You can also count on the increased BMR for that.

You should make sure to be in a caloric deficit and not a surplus to get the expected weight loss results.

You can use the Ketogenic Calculator to get your calorie deficit. It automatically sets your protein according to your activity level.

You need not worry about fluctuating calorie deficit calculator keto macros as long as you are taking in the required amounts in the ranges.

The numbers will finally meet.

When to stop calorie deficit?

Sometimes, the longer road is the road to sustainable results. Breaks are needed between bouts of hard work and change in almost every instance of life, and diet is no exception. Dr. Melissa Davis
health consultant (Renaissance Periodization) -

The RP program, conceiving to contribute to lasting results through lower or maintenance calories, recommends a period of deficit of 9-12 weeks and no longer than that.

After that, your remaining weight loss activity will need to wait for a maintenance period before resumption.

It is that period where you allow your metabolism to revitalize, and avoid starvation with calorie preservation.

You don’t need to worry about weight gain being below your normal caloric intake.

Still, your body needs to adapt to optimum calories and maintain the metabolic rate from the deficit for a stable new weight.

This period might initially seem confusing, but it remains valuable as it offers your mind to relax, free from the stress of counting your macros.

Then, a prolonged large deficit will result in a significant lack of energy, affecting your metabolism, while a surplus will start a weight rise.

You must know that a working structure is about finding the right diet if you have the experience. The best option is that which offers freedom on top of assistance.

A right diet will engage you in healthier daily practices with the right tools to succeed.

With Renaissance Periodization, you can use your own food preferences, convenience, and terms to reach your goals while keeping a high, adjustable metabolism and constant new weight.

Even making a drastic change in body composition through an 18 lbs weight loss over a year can become possible.

Calorie deficit or surplus?

There are situations where a surplus, too, can be considered.

To have muscle gains on a test E calorie deficit, for example, you can maintain or increase your calorie intake by 500cal, then decrease it onwards.

Or cut it down before your cutting cycle. With a controlled BMR, you can look forward to a 10% body fat.

The surplus can only be considered in conditions opposite to deficits, that is when having an initially high BMR and low body mass. Then, your goal is likely to be muscle gain.


Provided that you are respecting your calorie intake along with your deficit, a calorie remains a calorie. Be sure to retain protein and free all others during your dieting period.

You can consult a registered dietician or nutrition specialist to recommend a specific diet(s) based on your fat loss goals. Like exercises, deficits also require recovery time.

Whatever the goal, you also need to be patient. Although it is a long and tough process, try to enjoy it instead of rushing it since an overdo can only sabotage your goal.

References & Citations

  1. Legge, A. (October 15, 2013). How to Set a Caloric Deficit for Fat Loss. Retrieved May 31, 2020 from Complete Human Performance:
  2. Dolson, L. (July 17, 2019). Macronutrients 101. Retrieved May 31, 2020 from Verywellfit:
  3. Van De Walle, G., MS, RD. (December 12, 2019). What Is a Calorie Deficit, and How Much of One Is Healthy? Retrieved May 31, 2020 from Healthline:
  4. Kelso, T. (n.d.). The Right Way To Lose Fat: What To Eat. Retrieved May 31, 2020 from Breaking Muscle:
  5. Thompson, D. (May 25, 2010). Boost Weight Loss by Knowing Your BMR. Retrieved June 1, 2020 from Everyday Health:
  6. Clark, N. (October 13, 2017). How To Use Your BMR To Calculate A Caloric Deficit For Ideal Fat Loss. Retrieved June 1, 2020 from Nate Clark:
  7. Homer, B., Martins, N. (Nov 14, 2019). Do Calories Matter on a Keto Diet? Retrieved June 2, 2020 from HVMN:
  8. Connolly, E. (March 2, 2017).How Long Should I Be Dieting For? Retrieved June 2, 2020 from Trifecta:,shed%20those%20last%20few%20pounds
  9. Carlucci, S. (n.d.). 4 Reasons to STOP Counting Calories (Hint: It’s Super Inaccurate!) Retrieved June 2, 2020 from Athlean-X: