JavaScript Bookmarklet for Enhanced Macro Goals in MyFitnessPal

This JavaScript bookmarklet will enhance the macro target section of the custom goal editor  in MyFitnessPal with some advanced features that allow you to set up a more complex macro strategy.

Features:

• Set percentages in 1% increments
• Set targets in grams rather than percentage
• Set one of the three macros to  automatically fill any remaining calories in your daily goal that are not allocated to the other two macros
• Remember your advanced settings as long as you do not overwrite your changes with the default MFP 5% scheme

Example – Specify protein in grams, fat as a percentage, fill remaining calories with carbs

How To Install The Script

The script is available as a userscript for use in browser extensions like Greasemonkey (for FireFox) and Tampermonkey (for Chrome). Running like this, the fix is always there, even after you update, and you never have to manually run anything. You can install the script here:
http://karoshiethos.com/js/MFP_Macro_Fix.user.js

Internet Explorer and Safari users need to add the bookmarklet below to their bookmarks. When you are on the MyFitnessPal custom goal screen, click on the bookmark, and the form will be enhanced with these features. After you save your changes, the form will revert back to the default 5% increments, but your gram counts will be correct. The mobile apps will display your chosen percentages and grams properly. You will need to click the bookmark each time you want to change your macros.

Internet explorer users, right click the link in the blue box below and click “Add to Favorites”. Safari users, drag the link up to your bookmarks bar.

MyFitnessPal Macro Enhancements

How does it work?

The script is a small JavaScript class that adds components and logic, and integrates with the existing logic in the custom goals screen. When you are finished with your changes and submit the form, the grams for each macro are translated into high-resolution percentages (Example: Carb=44.56666666666666%, Protein=30.533333333333335%, Fat=24.9%), which are saved exactly the same way the default 5% increment percentages would be. MyFitnessPal will round the percentages to the nearest 1% when displaying percentages on the website and in the mobile apps, but they appear to use the high resolution percentages for calculating grams. In my testing, the gram counts always come out as specified.

I’m not sure why this functionality is not already available in MyFitnessPal, I think most users who are serious about their diet probably set up their macros by the gram, or in some combination of grams and percentages.

This is a quick fix I put together in my spare time. It may have bugs. If so, I may or may not fix them. I have tested this in Chrome, Firefox, Safari, and IE10 and 11 – it may not work in IE6, IE4 for Mac, NCSA Mosaic, Lynx, etc. in other words, if you are not running an up to date browser, YMMV. If you need help and your questions are not already answered in the comments, you can find me on Twitter at @robruchte or email me at rob.ruchte@gmail.com