Daily calorie need and calorie burn of your body

Calorie. Small but a very powerful word. You come across this word “Calorie” while reading a magazine about health, while buying something from the grocery(on the package), while doing some exercise at the gym, while talking to your doctor for your nutrition, while watching your tv, etc. As you come across that much, you know it is a unit of measure for what you eat and what you do. When you eat something, your body gets that calorie, when you do something your body loses (or uses) it. Ok, but what is Calorie, exactly? What do 100 calories mean? How many calories do our body need for one day? 

Calorie is the energy unit of measure we take from the foods. An egg has protein, carbohydrate, fat, vitamin and minerals with different amounts. Calorie of an egg, which is between 72-78, is the corresponding energy amount that our body gets when we eat the egg. And 35 years old, 100kg(220lbs) male needs 2,650 cal/day to remain his weight if he is lightly active.

You will find the logic behind calorie calculation and you will understand what 100 calories mean and its difference from 1,000 calories. You will find your daily calorie need, and how life routine, like sleeping, walking, watching tv, swimming, etc. affect your daily calorie need. And do you really need to exercise, by the way?

The Questions we will answer:

  1.   1. What is a calorie, BMR, BME, BEE, REE and how are they calculated?
  2.   2. What is your daily calorie need and what affects it?  
  3.   3. What is your daily calorie intake?
  4.   4. What is the difference between BMR and RMR
  5.   5. What is the activity level and how to find it?

1. Your Daily Calorie Need (BMR & Activity)

There are two groups of activities within your body. The first group is the basic metabolic functions that are happening in your body all the time, to keep you alive. You breathe, your heart beats, your blood circulates, your cells maintain and new cells produced, your body heat keeps at a level, you digest, etc. These activities form Basal Metabolism or Resting Metabolism of your body. And the number of calories your body needs for such activities are called Basal Metabolic Rate(BMR) or Resting Metabolic Rate(RMR). BMR and RMR are slightly different, look FAQ-1 for detail. I will continue with BMR.

The second group is the daily activities like walking, running, watching tv, swimming, playing table tennis, jumping rope, typing on the computer, etc. We can live without the additional activities if you call that “living”, but we can not live without the Basal Metabolic activities.

BMR calorie, together with the activity calorie form your daily calorie need. If you need to maintain your weight, you need to eat that much calorie(total of BMR & Activity). If you want to gain weight, you need more calories. And to lose weight eat less. Let’s continue with some cases.

In the images, you will see 8 cases. Age, length, and activity levels are the same. Weight and sex are different.

  • Age: 35-year-old,
  • Length: 175cm,
  • Activity Level: Slightly active,
  • Weight: 100kg(220lbs), 91kg(200lbs), 82kg(180lbs), 73kg(160lbs),
  • Sex: male and female.

Assume, in all 8 cases, the weight of all remain the same for a long time. They may gain 1-2 kg some months, lose 1-2kg in the other months. But the average weight is the same. This means there is a handshake with the daily calorie intake and daily calorie burn(BMR & Activity).

Daily Calorie Need = Daily Calorie Intake

Let’s talk on some cases..

2,650 is the daily calorie need for a 35-year-old, 175cm, 100 kg(220lbs), slightly active male (1,925 for BMR and 725 for Activity | case-1). As the person is not gaining weight, nor losing, calorie intake is the same too. The person burns all these 2,650 calories with his daily activities such as sleeping, walking, swimming, etc.

2,050 is the daily calorie need for a 35-year-old, 175cm length, slightly active 73kg(160lbs) female (1,490 for BMR and 560 for Activity | case-8). If she was 50kg(110lbs), daily calorie need would be 1,730 calories.

So, a 100kg male needs 600 calories more than a 73kg female, and 970 calories more than a 50kg female, just to remain his weight. You see? Weight affects the calorie you need. The more weight you have, the more calorie you need. Besides weight, what affects your daily calorie need?

2. What affects your daily calorie need and why?

Age, sex, height, weight and activity level affects the calorie you need. Let’s take case-1 and change one factor at a time.

  • Age: 2,650cal at 35-year-old decreases to 2,440cal at 65-year-old(-7cal every year),
  • Sex: 2,650cal for male decreases to 2,420cal for female,
  • Height: 2,650cal for 175cm increases to 2,735cal for 185cm(+9cal every cm),
  • Weight: 2,650cal for 100kg(220lbs) decreases to 2,280cal for 73kg(160lbs)(-14cal every kg),
  • Activity Level: 2,650cal for lightly active increases to 3,655 for extra active.

Sex: Your metabolism is your body’s ability to break down the food you eat and convert them into energy and also store as fat. And this process is very related to your muscle mass. Here is the very basic difference between fat cells and muscle cells: “Muscles do things in your body, like moving your body from one place to another. Digestion, heartbeat, breath, etc. are related with muscles. Fats, on the other hand just sit there and do nothing but wait as a fat storage.” This is why male needs more calories than female; they have more muscle.

Age: You do not notice at first, but as you get older, your muscle mass decreases, and your metabolism gets slower. Around age 30s, you start to lose a little bit of muscle and put on a bit more fat, when compared to 20s. This is why younger needs more calories than older. Cell construction is another reason for growing children(daily calorie need increases from 1,000 calories at 2 years old to 2,800 calories at 18 years old. But daily calorie need per weight decreases).

Height: As roughly 60% of BMR is consumed by organs and 40% from muscle, the bigger your organs are, the more calorie you burn. Guess what? Longer people have bigger organs in general. This is why taller people need more calories than shorter.

Weight: Your muscles carry more weight if you are heavier. This is the first reason why heavier people need more calories than lighter. The second reason is because the whole body has more cells to look after, which means more daily calorie need.

Activity level: No need to say much for activity level, I think. The more you walk, the more calorie you need.

3. What is your daily calorie intake? What can you do with that much calorie?

The equation is simple. You get the energy you need for your daily activities from the ingredients you eat. Ingredients have calories and your activities need calories.

  • If your daily calorie intake is more than you can consume, you gain weight,
  • If your daily activities are more than you eat, you lose weight.

This simple equation brings us to another very important two question; what is our daily calorie intake? What can we do with that much calorie?

Here is the case; we will spend 4 days eating together within a few minutes and understand the daily calorie intake from some very common foods. The first two days(Monday, Tuesday) in Burger King (or McDonald’s, etc.), on Wednesday and Thursday in different places or may be at home, office.

We will also calculate; with that much of calorie we eat, what can a 100kg(220lbs), 35 years old, 175cm, male do?

Important notice, which we will use in our further analysis:

1 lb fat = 3,500cal or 

1 kg fat = 7,500cal

  • If your body loses 7,500 calories, with eating less or with the activity you do, you will lose 1 kg.
  • In other words, if you intake or burn 500 cal/day more, within a week you lose 1lb or 0.45kg.

Day-1.Monday

This is an unhealthy day for our candidate who eats everything from Burger King, McDonald’s, etc. for the whole day. In breakfast croissant and iced coffee, for lunch and dinner whopper menu. Drink and french fries are small, no ketchup(10cal/packet) or mayonnaise(80cal/packet). For the whole day, no pie, no cookie, no coffee latte, etc. but just 1 oreo shake for snack/dessert.

What can you do with 3,930 calories?

3,930 calories in total. As an 100kg(220lbs) 35 years old 175cm lightly active male(Case-1), he needs 2,650 calories for the day. This is 1,280 calories more than he can burn at an ordinary day.

  • 3,930 calories give him the energy to sleep for 44 hours, walk for 12 hours, type computer for 22 hours, watch tv for 39 hours, swim for 4.5 hours and play table tennis for 9.5 hours.
  • To burn that extra 1,280 calories, he must walk an extra 4 hours or type computer an extra 7 hours or swim an extra 1.5 hours or play table tennis for extra 3 hours. If the candidate was a lighter female (for ex. case-8), the activity hours would be longer.
  • Extra 1,280 calories per day means 1 kg of mass gain(mostly fat) within a week.

Day-2.Tuesday

This is unhealthy day 2. Foods are from Burger King, McDonald’s, etc. again, but low calories selected. 2,540 calories are very near to 2,650 calories. So his daily activities will consume these calories. But if the candidate was case-8(2,050 cal/day) for example, she would gain weight.

Please pay attention: No sugar(12cal/cube) in coffee/tea, diet coke(0cal), no ketchup(10cal/packet) or mayonnaise(80cal/packet), no snack or desert other than cookies.

Day-3.Wednesday

Foods are from different places, home, office, etc. 3,608 calories in total which is more than 958 calories from the daily calorie he needs.

Please pay attention: No bread(66cal/slice), no sugar(12cal/cube) in coffee/tea, no ketchup(10cal/packet) or mayonnaise(80cal/packet), no snack or desert other than brownie.

Day-4.Thursday

Foods are from different places, home, office, etc. 1,279 calories in total which is very less from the daily calorie he needs. Indeed very close to the minimum calorie limit anyone must take.

Please pay attention: No bread(66cal/slice)(just 1 in breakfast), no sugar(12cal/cube) in coffee/tea, no ketchup(10cal/packet) or mayonnaise(80cal/packet), no snack or desert other than brownie.

By the way, Friday night entertainments, New Year’s days, birthdays, etc., which are the part of our lives, should be considered in the diet in longer terms.

4. Is it that simple, "calorie in - calorie out"?

I wish I could say yes… But, No it is not that simple. There are many other factors that affect this cycle. Understanding daily calorie need and calorie burn of your body is the first and very important step. You have to know it, but it is not “just that simple”. Here is why:

  • Nutrition Type: Fat, carbohydrate, protein, vitamins, minerals are compounds of nutrition we eat. Carbohydrates are the first energy source for our body. Rather than fats, our body tries to use carbohydrates. Sometimes the body can feel out of energy if there is just fat instead of carbohydrate in place. Our body has resistance to use fats.
  • Feeling of fullness: Proteins or fats make you feel full for a longer period than carbohydrates. Also, some type of carbohydrates makes you feel full for a longer period than other types of carbohydrates. And this affects the amount and frequency you eat.
  • Body Complexity and habits: Some people can not use fats as an energy source because of body types or previous diets. To change and make them use fats of their body and nutrition may take time. Moreover genetics, blood type, stress, sleep, liver/enzymes, thyroid, etc. are the other effects.
  • For instance, enzymes that burns fats, do their job after 2-3 hours of fasting. So if you eat frequently or have snacks between your meals, in fact, you block that enzyme. Then do not ask "the reason why you can not lose your fats"
  • Adaptiveness of your body: The metabolism of your body is adaptive. As you eat less, your metabolism slows, and the body tries to limit the energy expenditure.
  • Vitamins, minerals, fibers which do not affect the calorie value, do affect the metabolism
  • Storage status and usage after storing.

5. Conclusion

Knowing daily calorie need and calorie burn of your body make you able to compare and associate the nutrition you eat. Our 100kg case-1 male burns 73% of his energy with BMR. Remained 725 calories, which will be spent with other daily activities, is equal to a milkshake. You have to make this calculation and comparison.

Females are under more risk of gaining weight. Think about it; “a boy and his girlfriend, outside for a dinner, ordered the same spaghetti, the portions are the same”. As females have low BMR value and daily calorie need is lower, however, they eat the same amount, she will gain more weight. Eating the same may be a right but a misleading sentence.

Calorie calculation and “calorie in – calorie out” comparison is just a step. Yes, an important one; but there are more steps. The source of this calorie is very important. You can not compare a candy of 300 calories and a breakfast of eggs and cheese of the same calorie amount. This is a very first step on the way of your health & calorie journey.

I want to lose weight; so let’s go to the gym. Is it a right decision? Sports or being active is very important in our life and we have to add it as much as we can. Sports and activities have more role than just burning calorie. At that point, I must mention that; beginning sport, for losing weight is a bit misleading and deflects the main target. In a world of calorie(carbohydrate) bombs, like candies chocolates, pies shakes and huge meals( 1,000 + calories), losing weight and eating healthy is tightly connected to the nutrition you take. A pie or shake may worth 1 hr swimming. I do not even count the unhealthiness of it and the difficulty in maintainability if it is just for losing weight.

If the aim is just losing weight, think twice before subscribing to the gym. Because you will quit soon. Focus on your diet. This will make you healthier and more fit. But if you will not listen to this advice, at least begin something you really like. Such as football, basketball, table tennis, bowling, swimming, etc. Do something you enjoy and not quit. Do not look at the calorie burn of that activity. It always helps in the long run. Believe me.

I am happy that you passed the very first step of your health journey.

FAQ (Frequently Asked Questions)

BMR (Basal Metabolic Rate) or BEE (Basal Energy Expenditure) is measured in a darkened room after having an 8 hours sleep and 12 hours of fasting to be sure that the digestive system is inactive, and the body is fully on rest for a specified time frame. The person needs to sleep at the testing facility.

RMR (Resting Metabolic Rate) or REE(Resting Energy Expenditure) is measured under less restricted conditions than BMR. For instance, you do not need to sleep 8 hours right before the testing.

BMR and RMR are almost the same, except BMR will have a slightly more accurate reading.

BMR, RMR, BEE, REE is calculated in two ways. The first and more accurate way is using gas analysis through either direct or indirect calorimetry. As this is a bit difficult and costly, it is common to use the second way; estimation formulas which give close results to the gas analysis.

In below formulas, I will use some abbreviations.

  • w: weight (in kg), 
  • h: height (in cm), 
  • a: age (in years),
  • ffm: Fat-Free Mass,
  • bfp: Body Fat Percentage.

1. Mifflin – St Jeor Formula (1990 – The American Journal of Clinical Nutrition)

Mifflin – St Jeor Formula is believed to give the most accurate result and is the most commonly used.

BMR = 10w + 6.25h – 5a + s cal/day

s: “+5” for males and “-161” for females

  • Example-1: for Case-1 who is a 220lbs(100kg), 175 cm, 35 years old male, BMR = 10×100+6.25×175-5×35+5 = 1,000 + 1,093.75 – 175 + 5 = 1,923.75 cal/day.
  • Example-2: for Case-8 who is a 160lbs(73kg), 175 cm, 35 years old female, BMR = 10×73+6.25×175-5×35-161 = 730 + 1,093.75 – 175 – 161 = 1,487.75 cal/day.

Please find Mifflin – St Jeor Article in The American Journal of Clinical Nutrition.

2. Harris – Benedict Formula (1919)

Harris – Benedict Formula was the most common way to calculate your Basal Metabolic Rate for over 70 years till more accurate “Mifflin – St Jeor Formula”. Actually, the results are close.

BMR(male) = 66.5 + 13.75w + 5.003h – 6.775a cal/day,

BMR(female) = 655.1 + 9.563w + 1.85h – 4.676a cal/day

  • Example-1: for Case-1 who is a 220lbs(100kg), 175 cm, 35 years old male, BMR = 66.5 + 13.75*100 + 5.003*175 – 6.775*35 = 66.5 + 1,375 + 875.525 – 237.125 = 2,079.9 cal/day.
  • Example-2: for Case-8 who is a 160lbs(73kg), 175 cm, 35 years old female, BMR = 655.1 + 9.563*73 + 1.85*175 – 4.676*35 = 655.1 + 698.099 + 323.75 – 163.66 = 1,513.289 cal/day.

3. Katch-McArdle Formula

The equation is based on Fat-Free Mass (FFM) or Lean Mass. If you know your fat percentage, this formula may be more reliable. And works better in light weights.

BMR = 21.6 * ffm + 370 cal/day

ffm: = w – (bfp * w)

  • Example: for Case-1 who is 220lbs(100kg), bfp is 23%, FFM = 100 – (0.23 * 100) = 77 and BMR = 21.6 * 77 + 370 = 2,033.2 cal/day.

To calculate the your daily calorie need, you can either add all of your daily activities to your BMR value or multiply your BMR by your activity level. You can select an activity level multiplier from the below activity levels, or you can adjust it for you by selecting a multiplier between these multipliers. Here are the activity levels:

1. Sedentary (x1.2)

Little – no exercise, or activities of daily living only.

  • – a lot of time sitting at a desk or watching television,
  • – taking an easy walk,
  • – stretching,
  • – shopping,
  • – cleaning,
  • – watering plants,
  • – mowing the lawn,
  • – taking out the trash,
  • – walking the dog,
  • – In sedentary activities, you are able to breathe normally, and able to sing while you perform an activity.
  • – Under normal conditions, low-intensity exercise will not make you sweat.

 

2. Lightly Active (x1.375)

Activities that require standing up and moving around or, light exercise/sports 1–3 days/week.

  • – Housework like hanging out the washing, ironing, and dusting or,
  • – Working at a standing workstation,
  • – Daily exercise that is equal to walking for 30 minutes at 4mph or,
  • – Intense exercise, such as aerobics, skiing, jogging on a daily basis for 15-20 minutes or,
  • – Spending a good part of the day on your feet (teacher, salesman, etc.)

 

3. Moderately Active (x1.55)

Moderate exercise/work/sports 3-5 days per week or exercise less than 2.5 hr/wk of the moderate aerobic activity,

  • – Daily exercise that is equal to walking for 1 hour and 45 minutes at 4mph or,
  • – Intense exercise, such as aerobics, skiing, jogging on a daily basis for 50 minutes or,
  • – Spending a good part of the day doing some physical activity (e.g. waitress, mailman),
  • – Riding a bike on level surfaces,
  • – Playing doubles tennis,
  • – You breathe harder and deeper than at a sedentary level,
  • – You can’t sing any tunes, but you can hold a conversation as you take a brisk walk,
  • – After around 10 minutes of exercise, you should break into a sweat.

 

4. Very Active (x1.725)

Hard exercise/sports 6–7 days a week.

  • – Daily exercise that is equal to walking for 4 hours and 15 minutes at 4mph or,
  • – Daily exercise that is equal to walking for 27km (17 miles) or 34,000 steps or,
  • – Intense exercise, such as aerobics, skiing, jogging on a daily basis for 2 hours or,
  • – Spending most of the day doing a heavy physical activity (e.g. bike messenger, carpenter),
  • – In these exercises, your heart is working at maximum efficiency. Talking will be difficult at this level and you will breathe rapidly,
  • – You will break into a sweat after just a few minutes doing exercises like biking or hiking on hills, jogging, swimming laps, playing basketball or high-intensity aerobics.

 

5. Extra Active (x1.9)

Very hard exercise/sports and physical job or 2x training.

The mean weight gain during the 9 months of pregnancy is 12kg(26lbs) or 77,000 calories; 285 cal/day. As energy needs are different for each month; it is better to increase calorie intake at each month. Considering 285cal/day, beginning with extra 50-100cal/day in the first month, and then add extra +50cal/day in every month may be smooth support for the pregnancy.

For instance: +85(1), +135(2), +185(3), +235(4), +285(5), +335(6), +385(7), +435(8), +485(9).

!! The best calculation for the pregnancy can be done via your doctor. This calculation is just a guide.

  • Cutting 20% of your calory intake is called fat loss,
  • Cutting 40% of your calory intake is called extreme fat loss.

 

There is a rock-bottom figure for weight loss, describes the minimum quantity you should take at least. Different sources give different figures for that amount. Here are some:

  • 8 cal/lbs or 11 cal/lbs of body weight,
  • 1,200 cal/day (female), 1,500 cal/day (male).
  • 1 g of carbohydrates contains 4 kcal
  • 1 g of protein contains 4 kcal
  • 1 g of fat contains 9 kcal