Calculations: Part 3

Posted by Jen | Weight Loss | Saturday 9 February 2008 11:56 pm

I know my Maintenance Calories…now what?
Well, this is the final step in your calculations.
You now know how many calories you need to eat in order to maintain the same weight.
I calculated that number to be 1942.
If I eat 1,942 calories, my body will use all those calories to fuel all of its bodily functions and all of the activities I perform. It won’t need to use any of my fat stores or muscle stores because I gave it all the food fuel it needs. That is great if you are at a healthy goal weight…but if I want to lose weight, I need to eat below my maintenance level. I need to give myself a deficit every day.

If, for instance, I eat only 1500 calories a day, my body will use that 1500 to fuel itself, but because it burns 1942, it needs more than that. So it will then begin to use our fat (and muscle) stores to make up for the missing calories.
This is how we lose weight.

Just remember that it is important to choose a healthy, safe and steady deficit that will promote weight loss without harming our body.

How did I decide on my weekly weight loss goal/my deficit?

The general rule of thumb is to shoot for either 20% below your maintenance number or to try to lose only 1% of your body weight per week. Both of these options seem to provide a person with a safe and steady weight loss.

I chose the latter option because it gave me a larger deficit, while still keeping me above my BMR (which I think is really important. The body should at least get enough fuel for its basic bodily functions!)
So, one percent (1%) of my body weight is 1.3. I rounded that number down to 1 and made that my goal. I want to lose 1 pound a week.

I won’t go into to much detail here about choosing a goal that brings about too rapid a weight loss. I’ll just say that I personally think it is usually unnecessary, unhealthy, and counterproductive in the end. Always discuss with your doctor if you are planning a diet that severely restricts your calories.

Again, I think never going below my BMR is the rule of thumb I use.

How do I lose 1 pound of fat a week? What is my exact deficit?
To lose 1 pound of fat a week I need to consume 500 calories fewer than my maintenance calories per day.

One pound of fat = 3500 calories.
3500 divided by 7 days (in a week) = 500 calories a day.

This means that I have to have a 500 calorie deficit every day and by the end of the week…voila!..I have lost a pound. (In a perfect world, of course!)

The next step is to then take my Maintenance Calories and subtract the 500 deficit from it in order to get my Calorie Goal for weight loss. This will give me how many calories I can consume every day in order to lose 1 pound a week.

So what is my calorie goal?

My Maintenance Calories were 1942.
My deficit is 500.
That makes my Daily Calorie Goal: 1442.

This is the number of calories I can eat each and every day to lose 1 pound a week. We already know that my body needs 1942.
Well, I am only going to give it 1442.
The rest is up to my body…it must fend for itself.
It must start converting my fat stores into energy to make up for the missing calories.

And, so begins the road to my slow and steady, healthy and happy, weight loss!

Is there an easier way to do this? Without calculations on paper?
Here are some links to some online Calorie Goal calculators. Unlike the calculators in my previous post, these do more than just calculate your BMR/RMR. They do the whole thing! Just put in your stats and you are given a calorie goal to lose weight!

HEALTHY LINKS – This one is my favorite. You can use the advanced options to switch between a calorie goal based on the Mifflin-St.Jeor or Harris Benedict or lean body mass.
You can also test out their zig-zag calorie tool for those who like to “calorie shift” or “calorie cycle” or “zig-zag diet!” – this site gives you a nice calorie range. Based on the Mifflin-St.Jeor equation.

That’s all!

Calculations: Part 2

Posted by Jen | Weight Loss | Saturday 9 February 2008 11:54 pm

What happens now?
Well, we have our BMR/RMR number, but that isn’t enough.

Because an average person does not lie in bed all day without moving, eating, etc., your BMR/RMR only covers some of the calories you burn. You also have to count the calories you burn during your daily activities.

So, to find out how many more calories you burn, you need to multiply your BMR/RMR by the appropriate activity factor, as follows:

1. If you are sedentary (little or no exercise) : BMR x 1.2
2. If you are lightly active (light exercise 1-3 days/week) : BMR x 1.375
3. If you are moderately active (moderate exercise 3-5 days/week) : BMR x 1.55
4. If you are very active (hard exercise 6-7 days a week) : BMR x 1.725
5. If you are extra active (very hard exercise & physical job or 2x training) : BMR x 1.9

Personally, this is where I struggled the most.
I have a hard time figuring out where exactly I fit in. Some weeks, I workout really hard and do about 4-5 days of exercise and some weeks I only do 2-3 days. So, in the beginning, I multiplied my BMR by 1.45…which was somewhere between lightly and moderately active.

The number you get from this calculation will bring you to the total number of calories you burn every single day to fuel your basal/resting activities AND your normal activities.

For example, if I considered myself moderately active and if my BMR was calculated as 1253, I would get this number:
1253 X 1.55 = 1942

This is my Maintenance number. This is the number of calories I can eat to keep my weight exactly the same. So, if I give my body that amount of calories, I will stay the same weight.

If I want to lose weight…I give my body fewer calories.
If I gave my body only 1600 calories, it would still burn 1942 calories, but not all of those burned calories will come from food because I didn’t eat that much.
It would use the 1600 calories I ate…and then start burning fat and muscle for the rest of its necessary fuel.
That is how you lose weight.

Now, it’s finally time to figure out my Daily Caloric Intake Number…the actual number of calories I should consume each day to lose weight.
On to Calculations: Part 3. The final chapter!

Calculations: Part 1

Posted by Jen | Weight Loss | Saturday 9 February 2008 11:53 pm

I am a sucker for those online calorie calculators. Every time I come across a site with one, I use it. I don’t know if I am looking for confirmation that I am using the right calorie goals or if I’m just a numbers nerd.

In any case, due to the fact that I lose weight by tracking calories, the right calorie intake numbers are important to me. I try to get as accurate a calculation as possible.

To find my daily calorie intake number I can go the short way and use an online calculator (I have some links at the bottom of my “Calculations: Part 3″ post) or I can do it the long way:

Step One: Calculate my BMR/RMR.
Step Two: Multiply that number by an activity multiplier to get my Maintenance Calories.
Step Three: Subtract a deficit from my Maintenance Calories to get my Daily Calorie Goal.
Step Four: Eat, exercise and stay as close to my Calorie Goal as possible!

This post will cover Step One.

What is the BMR and RMR?
BMR stands for Basic Metabolic Rate. RMR is my Resting Metabolic Rate.

Basically, my BMR or RMR estimates the amount of calories my body will burn while at rest. If I were to lie in bed all day (no getting up, no moving around…) I would burn a certain number of calories. That number is represented by my BMR/RMR.
The chart below will give you an estimated breakdown of my daily caloric burn:

60-70% – Basic bodily functions (…breathing, temperature regulation, etc.) as represented by my BMR or RMR.
15-30% – All physical activity (walking, running, cooking dinner, chewing gum, tapping my toes…anything other than lying in bed all day.)
10% – Thermic effect of food. (Calories burned through the digestion, asborption and storage of food.)

What is the difference between the two terms BMR/RMR?
These terms are often used interchangeably and the difference between the two is relatively minor.
The difference basically comes from the fact that each rate is clinically measured under two different types of conditions. To get a subject’s BMR, he or she must be in a fasted state (so that digestion calories do not play a part in the calculation) and the subject must be in a state of complete rest and in dark, quiet surroundings. It basically just tests how much you burn through regular biological functions.

The test for a person’s RMR is not as strict. The subject must be resting, but the calculations can include a some physical disturbance and possibly some digestion. This goes above and beyond BMR testing and includes any additional minor activity that occurs during a rested state.

In any case, we really don’t have to worry about any that and we can simply find our estimated BMR or RMR by using an online calculator or by using the equations I will provide below.

What type of BMR/RMR forumlas are available?
Currently there are two popular math formulas to use in order to figure out a person’s BMR or RMR. These two formulas are the Harris Benedict Equation and the Mifflin-St.Jeor Equation.
(Note: There is also a way to determine your caloric intake number by lean body mass called the Katch-McArdle formula. However, most people – including myself – do not know their lean body mass, so I won’t talk about that method.)

I don’t like math. Where are some good online BMR/RMR calculators?
The links below will bring you to two online BMR/RMR calculators:

BMR Calculator (uses the Harris-Benedict Equation)
My Fitness Pal (uses the Mifflin-St.Jeor Equation)

Which do I personally use and why?

I currently use the Mifflin-St.Jeor formula.

While the Harris-Benedict formula is more popular, it has been tested and reported to be slightly more inaccurate than the Mifflin formula. The Harris-Benedict numbers tend to be slightly overestimated (meaning you might be eating more than you should!)

However, some people have great success using Harris-Benedict and many of the popular dieting sites use that formula for their calorie calculations, so it really is up to you to test the numbers and figure out which works best for you.

Just a quick note….it appears that many times a site will use the Mifflin-St.Jeor equation and call the result your “RMR” and then use the Harris-Benedict equation to get a person’s “BMR.”
Other sites may use both formulas and call both results your “BMR”. Don’t let that confuse you. They are really talking about the same thing and the most important thing is the number you get from using either formula.

I like math! H
ow do I calculated my BMR/RMR on my own?
First, you need to convert your weight and height into kilograms and centimeters.

This is done by:

Dividing your weight (in pounds) by 2.2.
Multiply your height (in inches) by 2.54.


A 33-year-old female. You weigh 134 and I am 5’1″ (or 61 inches).
134lbs. divided by 2.2 = 60.9 kilograms
61 inches multiplied by 2.54 = 154.9 centimeters

Now, you take those numbers and plug them into one or both of the formulas below.

* Mifflin-St Jeor Equation *

Men: RMR = (9.99 X weight) + (6.25 X height) – (4.92 X age) + 5
Women: RMR = (9.99 X weight) + (6.25 X height) – (4.92 X age) – 161

A 33-year-old female. You weigh 134 and I am 5’1″ (or 61 inches).
134lbs. divided by 2.2 = 60.9 kilograms
61 inches multiplied by 2.54 = 154.9 centimeters

(9.99 X 60.9) + (6.25 X 154.9) – (4.92 X 33) – 161 =
608.39 + 968.13 – 162.36 – 161 =

My BMR/RMR = 1253
So, according to the Mifflin-St.Jeor forumla, these are how many calories you would burn just by lying in bed all day long.

*Harris-Benedict Formula*

66.5 + (13.75 X weight in kg) + (5.003 X height in cm) – (6.775 X age in years)
655.1 + (9.563 X weight in kg) + (1.85 X height in cm) – (4.676 X age in years)

A 33-year-old female. You weigh 134 and I am 5’1″ (or 61 inches).
134lbs. divided by 2.2 = 60.9 kilograms
61 inches multiplied by 2.54 = 154.9 centimeters

655.1 + (9.563 X 60.9) + (1.85 X 154.9) – (4.676 X 33) =
655.1 + 582.39 + 286.57 – 154.31 =

My BMR/RMR = 1370
According to the Harris-Benedict formula, these are how many calories you would burn just by lying in bed all day long.


Mifflin-St.Jeor = 1253
Harris Benedict = 1370

Two different equations…two different results.
It’s up to each person as to which formula they want to use.

Okay I used the calculator (or did the math.) What happens now?
I now have my BMR/RMR.
Remember this number only accounts for some of the calories we burn each day (about 60-70%). We need to find an estimate of all the calories our bodies burn each day.
This means you have to add youractivity calories, too. That is the only way you can get the best estimate of the total number of calories your body needs every day.

I will explain this next step in the post called “Calculations: Part 2“. This is where I calculate in activity levels to find Maintenance Calories.

Note: Remember, there are online calculators to do all of this for us, but some people like to see where the numbers come from, which is why I am explaining it all here.