A small library for calculating the calorie and macro breakdown for the If It Fits Your Macros diet.
Note: While this library is based on scientific formulas, everyone is different, so it can only provide an educated estimate for a person's calorie and macro requirements. Keep this in mind when using information obtained from this library.
IIFYM.js should work both in the browser and with NodeJS.
For the browser, you can simply install with Bower.
bower install iifym.js
For NodeJS, use NPM.
npm install iifym.js
If neither of the above methods meet your needs, you can download iifym.js from this repo on GitHub, or clone the repo to your machine and then copy iifym.js to the desired location. It is completely self-contained.
<script src="iifym.js"></script>
<script>
console.log(iifym.tdeeGoal(2408, 1.05));
</script>var iifym = require('iifym.js');
iifym.tdeeGoal(2408, 1.05);IIFYM.js provides a simple way to calculate the calorie and macro breakdown
with the calculate() function. However, it also exposes the functions
necessary to calculate the Basal Metabolic Rate (BMR) bmr() and the Total
Daily Energy Expenditure (TDEE) tdee() which are useful values for many diet
plans. Providing these functions separately also simplifies the creation of
interactive interfaces.
The BMR is the first step to determining your daily calorie and macro requirements. Your BMR is the number of calories required to keep you alive when you are at rest. You should consume at least your BMR of calories each day.
To calculate your BMR with IIFYM.js, we need some information. This information should be stored in an object with the following format, with the values changed accordingly.
{
'gender': 'male', // Required if using Mifflin-St Jeor
'age': 22, // Required if using Mifflin-St Jeor
'isMetric': false, // Provide metric inputs? (cm, kg)
'ft': 5, // Required if using Mifflin-St Jeor and isMetric == false
'in': 10, // Required if using Mifflin-St Jeor and isMetric == false
'cm': null, // Required if using Mifflin-St Jeor and isMetric == true
'lbs': 170, // Required if isMetric == false
'kg': null, // Required if isMetric == true
'mifflinStJeor': true, // True for lean individuals, false for overweight
'bodyFatPercentage': null, // Required if not using Mifflin-St Jeor
}IIFYM.js supports both metric and imperial measurements. The isMetric field
determines this behavior. When true, IIFYM.js will simply use the values
provided in kg and cm. When false, IIFYM.js will convert the values in
ft, in, and lbs to the appropriate metric values.
Two BMR formulas are currently supported, Mifflin-St Jeor and Katch-McArdle.
Mifflin-St Jeor takes into account gender, height, weight, and age when determining
BMR. Because of it does not account for how lean, or not, an individual is, it
is best suited for people in moderate shape. Katch-McArdle only considers lean
body mass. This makes it better suited for individuals at each extreme of the
weight spectrum where the huge presence, or absence, of body fat can skew the
calculation. Setting mifflinStJeor to true selects the Mifflin-St Jeor
formula as expected. Setting it to false selects the Katch-McArdle formula.
Whether or not a field is required depends on the options used. The comments above explain when a field is required. Otherwise, it can be omitted.
Once you have gathered the required data, you can calculate the BMR very easily.
// This and all following examples assume iifym.js has been required or loaded
// and is available as iifym
var data = { /* gather the necessary data and create an object with the keys from above */ };
var bmr = iifym.bmr(data);TDEE is the amount of energy (calories) used each day during your normal routine. It augments your BMR with an activity level to account for energy used during your 20-minute, morning walks or your 5 day a week Zumba and deadlifting sessions.
Once you've calculated your BMR (See above), you can calculate your TDEE by simply providing it along with your activity level to IIFYM.js.
IIFYM.js supports 10 activity levels. Each level is associated with an integer
ranging from 0 to 9. The levels are listed below. You will select the
appropriate level by passing its corresponding integer to the tdee()
function.
0 => BMR
1 => No exercise (desk job/sedentary)
2 => 3 times/week
3 => 4 times/week
4 => 5 times/week
5 => 6 times/week
6 => 5 times/week (*intense)
7 => Every day
8 => Every day (*intense) or twice daily
9 => Daily exercise + physical job
var bmr = /* See above */
// Assuming I'm active every day (7)
var tdee = iifym.tdee(bmr, 7);Once you have your TDEE, you have to decide what your goal is. Do you want to lose weight (cut), maintain, or gain weight (bulk). Your goal TDEE is the number of calories that helps you achieve that goal.
It is calculated by multiplying your TDEE by a goal value. This value should be between 0.75 and 1.15. A goal of 0.85 represents a 15% calorie deficit per day resulting in weight loss. Likewise, a goal of 1.05 represents a 5% calorie surplus per day resulting in weight gain. 1.0 is maintenance.
var tdee = /* See above */
// Assuming a goal of bulking with a 5% surplus per day
var tdeeGoal = iifym.tdeeGoal(tdee, 1.05);If you're just interested in how many calories you need each day along with how many grams of carbs, proteins, and fats you should be eating, keep reading.
IIFYM.js provides a convenience method when all you want to know is how much to
eat per day. This method (calculate()) requires the same information as
bmr() along with a few other items. These items are exerciseLevel, goal,
protein, and fat.
If you've been reading along, you can probably guess that
the exerciseLevel corresponds to the value used to calculate the TDEE
described above. Also, it's probably obvious that the goal corresponds to the
value used to calculate the Goal TDEE similarly detailed above. However,
protein and fat may not be as obvious. They are simply the desired number
of grams of protein (or fat) per pound of body weight (or lean mass in the case
of Katch-McArdle). The recommended values for protein are 0.7, 0.8, or 0.9. The
recommended values for fat are 0.30, 0.35, or 0.40. However, these can be
customized on an individual basis.
With all of this information, IIFYM.js can determine how many calories and grams of carbs, protein, and fat you need to reach your goal.
var data =
{
'gender': 'male', // Required if using Mifflin-St Jeor
'age': 22, // Required if using Mifflin-St Jeor
'isMetric': false, // Provide metric inputs? (cm, kg)
'ft': 5, // Required if using Mifflin-St Jeor and isMetric == false
'in': 10, // Required if using Mifflin-St Jeor and isMetric == false
'cm': null, // Required if using Mifflin-St Jeor and isMetric == true
'lbs': 170, // Required if isMetric == false
'kg': null, // Required if isMetric == true
'mifflinStJeor': true, // True for lean individuals, false for overweight
'bodyFatPercentage': null, // Required if not using Mifflin-St Jeor
'exerciseLevel': 2, // See exerciseLevelActivityMultiplier()
'goal': 1.05, // TDEE Modifier. Recommended: Maintain(1.0), Cut(0.85 or 0.8), Bulk(1.05 or 1.1)
'protein': 0.7, // Protein grams per lb of body weight. Recommend: 0.7, 0.8, or 0.9
'fat': 0.35 // Fat grams per lb of body weight. Recommend: 0.3, 0.35, or 0.4
};
iifym.calculate(data);
// {
// 'bmr': 1779, // BMR with no modifiers
// 'initialTdee': 2446, // TDEE without goal modifier
// 'tdee': 2568, // TDEE with goal modifier
// 'protein': 119, // Protein grams per day
// 'fat': 59.5, // Fat grams per day
// 'carbs': 389.1 // Carb grams per day
// }After much deliberation and research, I decided to go with try..catch style
thrown errors. The exported functions are all synchronous and, from what I
could find, the Node community tends toward throwing errors with synchronous
functions. I tried to make things as straightforward as possible. Each function
validates it's arguments and could throw an Error object that includes an
invalidProperties property containing an array of objects that provide more
detailed information. The error message is built based on the messages of the
invalidProperties objects. This should provide a unified means of dealing
with any errors that may come up. It should also simplify tying
errors to specific form elements in interactive uses.
// For example, passing a negative value for bmr to tdee()
iifym.tdee(-200, 2);
// Uncaught Error: ArgumentError: Invalid properties - bmr must be greater than 0
// Inspecting the error object
try {
iifym.tdee(-200, 2);
}
catch (e) {
console.dir(e.invalidProperties[0]);
// Object
// fields: Array[1]
// 0: "bmr"
// length: 1
// message: "bmr must be greater than 0"
// name: "bmr"
}While there are several online IIFYM calculators, I have yet to find one that is convenient on mobile. I've been wanting to create an alternative for awhile, and the discussion I recently came across on Reddit (https://www.reddit.com/r/Fitness/comments/2z8prt/programmer_here_i_can_make_a_new_iifym_calculator/) was the motivation I needed to put something together. Specifically the comment providing the formulas in one place. I see this library as the first step to developing a modern IIFYM calculator.
Of course, it's not limited to a simple interactive calculator. It could also be used to calculate breakdowns for an entire database or CSV full of people. You're free to be creative with this library and you don't have to depend on an online provider sticking around for as long as you want to stick to IIFYM.
So, feel free to contribute back to IIFYM.js and/or use it to create some awesome new tools for managing bodyweight.
MIT. See LICENSE
Create an Issue or, if you're feeling really generous, open a Pull Request with a solution. I'll get back to you as quickly as possible.
Interested in contributing? Awesome! I want to make contributing as painless as possible and I'm always open to suggestions.
Here's the basic idea:
- Create an Issue. Communication is a good thing.
- Clone the project if you haven't already.
- Install the development dependencies -
npm install - Make sure the tests pass before you change anything -
npm test - Create a feature branch -
git checkout -b adding-something-awesome - If you're adding a new feature or fixing a bug, add/fix any relevant test case(s)
- Make your change(s)
- Make sure the tests are passing -
npm test- If you get stuck but think you've made some real progress, go ahead and submit a Pull Request, but leave a comment mentioning that you could use another set of eyes. Perhaps we can solve the problem together.
- Submit a Pull Request
- v1.0.0 - ISHIS (I Sure Hope It's Stable)
- As promised, a stable version with error handling.
- The test suite now tests that validation is performed correctly.
- A new
macros()function is available so thatcalculate()doesn't need to be called when input changes in interactive interfaces.
- v0.9.0 - Initial Public Release
- This is the first release to be officially tagged and published. I decided to spend a couple days putting this library together while I have the time and motivation. The only reason it's not v1.0.0 is because there's no error handling to speak of in IIFYM.js. The API will likely change to return an error when given invalid data as is standard practice in NodeJS. Rather than release v2.0.0 so soon, I'm going to hold off on v1.0.0 until error handling is in place. Regardless, accurate results will be returned when given valid data, so it's possible to begin implementing this library now with the understanding that v1.0.0 will likely introduce breaking changes.
- Successfully calculates BMR, TDEE, Goal TDEE, and macro breakdown (with passing test suite).
- BMR, TDEE, and Goal TDEE can be calculated independently of macros if desired.
- Available on NPM and Bower.
- Compatible with the browser and NodeJS.