IIFYM BMR Calculator

1 Calculate your Total Daily Energy Expenditure

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Understanding The BMR Calculator

On a mission to get lean? Want to pack on pounds of muscle mass? Trying to master your body composition and succeed with your fat loss goals?
It is no secret that IIFYM.com is the authority on flexible dieting. We help people burn fat and build muscle at an alarming rate. Our clients make amazing progress while eating the foods that they love, without the suffering that one might expect with a traditional fat loss diet.

We have clients coming to use each and every day asking for help. When they do, one of the very first things we do is figure out their basal metabolic rate using a BMR calculator. If you want to succeed at making any sort of body composition changes, whether it’s to gain or lose weight, you need to know your BMR.

BMR = Basal Metabolic Rate (similar to RMR = Resting Metabolic Rate, but for IIFYM and flexible dieting purposes, there is a distinction between the two).
Your BMR is represents the number of calories your body burns at rest. The IIFYM BMR calculator will calculate the precise amount of calories your individual body requires to keep you alive. IIFYM It starts with your BMR calculation, moves on to your TDEE and ends with your fat loss macros.

Still confused about your BMR? Read on and I’ll explain it all to you!

So what is the basal metabolic rate and how does one figure it out? Let me share these details with you so that you get a better understanding of why it’s such an integral part of the process we use when working with clients.

What Is Your Basal Metabolic Rate?

Your basal metabolic rate is essentially the sum of all the energy your body uses each day to simply stay alive. Note this is not the number of calories needed to get you out of bed in the morning, to brush your teeth, or to cook the breakfast you’re eating on your IIFYM approach.

This is simply the energy required to keep your heart beating, your lungs taking in oxygen, your brain functioning, and all the other everyday tasks your body does to maintain life. As the name suggest basal means fundamental. If you sat in bed all day long and didn’t move a muscle, this is how many calories you’d burn.

When we use a BMR calculator with our clients then, we are figuring out this number. From here, this gives us a much better idea how to formulate a fat loss diet plan for them.

Please do keep in mind that no BRM calculator will never be 100% accurate however as your body is constantly changing on a day to day basis. If you are injured for instance, your body will be working harder to help repair that injury and as such, you will be burning more calories because of it.

This said, if you use the right BMR calculator, we’ve found that it’s accurate enough that you can then use it with other diet calculators to come up with a solid weight loss or muscle building approach that will work incredibly well for 99% of the population.

BMR Versus RMR – What’s The Difference?

If you’ve been reading up on various fat loss diets and fat burning programs, chances are, you’ve heard of something called resting metabolic rate as well.

One of the most common questions we get from our clients looking for fast fat loss results is what the difference is between basal metabolic rate and resting metabolic rate.

There isn’t a great difference here, but your resting metabolic rate adds to your basal metabolic rate the calories burned during the process of digestion as well as light movements that don’t involve formal activities.

So your resting metabolic rate RMR will always be slightly higher than your BMR results. When we dial in our clients macros, we prefer using a BMR calculator as a baseline as we feel it gives us a better number to work from when figuring out the rest of the dietary numbers used in an IIFYM fat loss program.

Why Does BMR and TDEE Matter?

So what do the results from our BMR calculator tell us?? Why does it help with fat loss results?

The reason we feel getting a client’s BMR results is so very critical is because it gives us a starting point to work off of.

Remember, in order to successfully lose body weight, you really need to only accomplish one thing:

Eat fewer calories than you burn.

Notice I did not say, “eat fewer calories than your BMR”. When calculating diet calories, we need to go off of your TDEE. This is the single most important number when it comes to the IIFYM Diet program.

An Important distinction

Most of our clients come to us thinking that the BMR is where their diet starts. This could not be further from the truth, and we encourage you not too fall in to the same trap that so many followers of IIFYM have before. As explained above, your BMR is the number of calories your body needs as a baseline. This does not include calories you burn during work, play, exercise, digesting food, or anything else. Your BMR is only the number of calories your body needs, basically in a coma.

Once we calculate your BMR, we need to add to it the calories you burn through all of your activities through out the day. This could as anywhere from 50% to 200% or more, to your BMR. When everything is totaled up, this number is called your TDEE, and that is the number we back calories out of in order to trigger immediate fat loss with our clients.

So while eating fewer calories, it is important to know how few is too little or too many. This is where a BMR calculator and TDEE calculator can be very helpful!
If you can do this, science has proven, you will start burning fat and losing weight at an immediate and predictable rate.

Likewise, if your goal is to build muscle mass, you again need to turn to a diet calculator that will figure out your BMR value, and then your TDEE after that. To build muscle, you need to do the opposite approach of losing fat. Building muscle requires that you consume more calories than you burn so that your body has something to build that muscle out of.

Until you provide the raw materials, you simply will not see success taking place. The calorie surplus in this case is an absolute must.

Of every single client that we have ever worked with, we have not come across even one who was able to consume more calories than they’ve burned off and lose weight. Science backs this up as well. Every study you look at showing fat loss results will indicate that the test subjects were eating in a calorie deficit.

This all comes down to the first law of thermodynamics – that energy cannot be created or destroyed. When you need energy to fuel your daily activities and it’s not available from the foods you are eating, you’ll tap into stored body fat to provide that energy.
Likewise, if you consume more energy than your body burns off, that energy has to go somewhere. The result is that it gets converted into both body fat as well as muscle mass.

We stress the importance of this relationship to our clients so that way they fully understand how seriously they need to take monitoring their calorie and macronutrient intake as part of their flexible dieting approach.

The BMR Calculator

When looking for a BMR calculator, you are likely to come across a few different variations. We have found that the absolute best BMR results come from using the Miffin-St Jeor equation, which is why we base our BMR calculator on this formula.  We’ve found through working with clients that other formulas, specifically the Harris-Benedict equation, which is another very commonly used BMR calculator, overestimate the total calorie burn, this can lead to stagnant progress.

BMR Calculation

We also like the fact that this equation doesn’t require you to know your body fat percentage, which we’ve found most of our clients do not know. Getting assessed for your exact body fat percentage to use in a diet calculator can be a costly procedure depending on where you are located, so it’s best to use a BMR calculator that doesn’t require this number.

Figuring Out Your BMR Calculator Stats

Ready to use our diet calculator and get started on a path to reaching your goals?

Check out our BMR calculator below.


I'm a woman
I'm a man
Years
15 80
Imperial
Metric
Ft
In
Cms
4'0" 120 8'0" 245
LBS
KGS
90 LBS 36 KGS 600 LBS 227 KGS
Total body weight formula
Lean mass formula Currently Body Fat %
Sedentary

Spend most of the day sitting (bank teller, desk job)

Light Activity

Spend a good part of the day on your feet (teacher, salesman)

Active

Spend a good part of the day doing physical activity (waitress, mailman)

Very Active

Spend most of the day doing heavy physical activity (messanger, capenter)

Days
0 7
Min
0 Min 360 Min
Light

I can hold a conversation while working out and do not break a sweat

Moderate

I am breathing very hard and challenge myself.

Difficult

Always break a sweat & have an elevated heart rate. I cannot hold a conversation.

Intense

Don't talk to me, don't look at me. I m here for a purpose and I might die today.

Summing Up On BMR Calcualtor

All in all, it’s important to remember that the BMR results you get are just a starting point. With our clients, we take the BMR results and put this into another diet calculator to figure out the appropriate amount of carbs, proteins, and fats to help our clients reach their goals. Then from there, we make adjustments as time goes on.

You should always be adjusting your diet intake based on the real world results you see. This is how we ensure that our clients always realize maximum fat loss results with their IIFYM protocol.

Your body is constantly changing and as such, your diet should be as well. A good BMR calculator is simply a starting point that helps you get to the end results you want to see that much faster.

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