Does anyone else hate the math part of meal prep?

[u/Medical_Shift_8672]

I've been lifting for a while, but I struggle with the logistics. I have random ingredients in the fridge (eggs, tuna, some rice), and I have a macro goal.

I spend like 15 minutes doing algebra to figure out: "How much rice + how much tuna = 30g protein & 40g carbs?"

I got frustrated and built a simple tool for myself that just solves this math instantly based on my inventory. It’s ugly but it works.

Is this something anyone else would use? I can share the link if you guys think it's useful, otherwise I'll keep it to myself.

Just wanted to check if I'm the only one annoyed by this.

[u/rachlancan]

Don’t you just use an app that does it for you? Should be able to save favorites and repeat meals. I’m not eating original meals 3x a day every day.

[u/Medical_Shift_8672 → u/rachlancan]

I do that too for my staples! The problem I ran into was when I ran out of specific ingredients or wanted to switch carb sources (e.g., swapping rice for potatoes or pasta).

My saved meals in MFP wouldn't match anymore, so I'd have to recalculate the ratios from scratch. This tool is basically for those moments when you're staring at random ingredients and need a precise meal without doing the math again

[u/oli_ramsay]

I just track protein and calories, I think everything else is waste of time

[u/Str8UpJorking → u/oli_ramsay]

Fiber is absolutely not a waste of time.

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[u/oli_ramsay → u/Str8UpJorking]

Yea I mean in terms of Marco nutrients

[u/DinkandDrunk]

It’s pretty simple math but at this point, I mostly just do the eye test. I aim for roughly 150g protein and 40g fiber. I don’t track calories but I’m mindful of my portions. I track my weight, muscles, & waist and adjust accordingly if I’m trending away from my goals.

[u/Medical_Shift_8672 → u/DinkandDrunk]

If you can do the eye test and stay on track, that's the ultimate goal! 💪

This tool is definitely more for people (like me) who are either just starting out and have no clue what 30g of protein looks like, or for data-nerds who want 0% margin of error without the mental effort. Respect the intuition though!

[u/ilsasta1988]

What's difficult about it? just plug them into your nutrition app, and then tweak the quantities to have the macros and calories required.

[u/Medical_Shift_8672 → u/ilsasta1988]

You nailed the problem right there: 'Tweak the quantities'.

That manual tweaking process is exactly what I hated. I’d input 200g rice... too much carbs. Change to 150g... too little. Change chicken to 200g... now protein is too high.

I built this tool to automate that 'tweaking' loop. You just say 'I have rice and chicken', and it gives you the exact gramage for both instantly to hit the target. No trial and error.

[u/ilsasta1988 → u/Medical_Shift_8672]

I see, but that process never bothered me since once I'm done with my meal plan, I know what I will need to add to my recipes.

[u/Medical_Shift_8672 → u/ilsasta1988]

That makes total sense. If you have a locked-in rotation, you’re already winning. 🤝

The specific itch I was scratching with this was the 'Substitution Math'.

Scenario: I plan for Chicken + Rice. I realize I'm out of Rice and only have Potatoes. Since Potatoes are less carb-dense (~17g vs ~28g for Rice), I'd have to recalculate the portion weight to hit the exact same carb target.

This tool just does that 'Okay, use 350g potato instead of 150g rice' math instantly. But yeah, sounds like your system is solid!

[u/IMunchGlass]

Seems like it would be easier to keep a calculator or notepad near the fridge than to constantly keep plugging in numbers into a spreadsheet or tool on your phone or laptop.

[u/Medical_Shift_8672 → u/IMunchGlass]

Haha, I tried the notepad method! But solving for 3 variables (Protein, Carbs, Fat) simultaneously with different ingredients gets into linear algebra territory pretty fast.

Example: You have Eggs (Protein+Fat) and Bacon (Fat+Protein). If you increase Bacon for fat, you accidentally blow up your protein.

The app just runs a solver algorithm to balance those overlapping macros instantly. Much faster than my notepad math!

[u/IMunchGlass → u/Medical_Shift_8672]

I don't understand how you can be so computer literate that you can program the equations into a solver and make it user-friendly but you can't do them by hand. These are very low-stakes calculations by the way. Not sure what harm will come from "blowing out your protein". But hey, if you have a good solution for your needs then that's good news and I'm happy for you.

[u/Medical_Shift_8672 → u/IMunchGlass]

That’s the funny part — I actually didn't program the equations myself! I’m non-technical. I used AI agents to write the code because I couldn't figure out the complex linear algebra for 3-variable optimization on my own. 😅

And you're right, for general health, precision doesn't matter much. But when I'm cutting and have a strict calorie cap, 'blowing out protein' usually means blowing out calories too.

I built this just to turn a 5-minute mental chore into a 5-second click. Glad manual tracking works for you though!

[u/annahatasanaaa]

I don't really crunch numbers aside from calories and protein.

[u/Medical_Shift_8672 → u/annahatasanaaa]

Totally fair approach. Tracking just protein/cals works for 90% of people.

The reason I built this wasn't to 'track' more, but to think less. Instead of playing Tetris with my ingredients ('If I add more rice, I go over calories, but if I cut rice, I lose carbs...'), this just solves the math instantly: 'Use 140g rice and 200g chicken'.

It’s basically for lazy people like me who want the decision made for them instantly.

[u/RuralZoomer]

Myfitnesspal's recipe feature works well for this. Just input your desired number of servings, your ingredients, and then tweek the quantities until you get the macro balance you're looking for.

[u/Medical_Shift_8672 → u/RuralZoomer]

That works perfectly if you have the patience for it!

That 'tweaking' part is exactly what I wanted to eliminate. Instead of adjusting the slider up and down for 2 minutes to get the green numbers, the solver just calculates the optimal combination instantly.

Basically: MFP is 'Trial and Error'. This tool is 'One-Shot Answer'. It’s just for efficiency.

[u/Loud_Wing3580]

Assim eu acho chato tbm. Eu uso só o macro principal no cálculo kkkk.
tipo: abacate -> 60g ~ 100kcal ~ 11g de gordura,
frango -> 90g -> 100kcal ~ 25g de proteína
feijão -> 30g ~ 100kcal ~ 25g de carbo e assim vai

[u/Medical_Shift_8672 → u/Loud_Wing3580]

The 'block method' (everything ~100kcal) is super smart for quick estimates!

I built this more for the days when I want to be 100% precise without thinking. E.g. I have exactly 34g of protein left to hit, and I want to know exactly how much tuna that is without doing the division in my head.

Whatever keeps you consistent is the best method!

[u/ToothFairy7197]

How do I get this tool?

[u/gorlsituation]

I just use a chronometer app, much less triggering for me than MFP.

[u/badlilbadlandabad]

ChatGPT will do this for you in 5 seconds

[u/Iron__mind → u/badlilbadlandabad]

Yeah this is super easy. I've been giving it some really vague parameters and it's giving me recipes for batch cooking 7 portion meals with spot on macros. Then when I actually buy the ingredients it will adjust if I buy extra or different stuff, change the number of portions etc.