I think I broke physics

BigT555

So bear with me here, I was just doing some brain thinking and realized something

if you eat 1 gram of pure fat, thats 9 calories. And to lose 1 lb you need to burn 3500 calories, or conversely to gain a lb you need to eat 3500 calories (above/below TDEE).

so 1 g of fat= 9 cals

9 cals divided by 3500 cals/lbs = 0.0025714285714286 lbs

0.0025714285714286 lbs times 453.592 g's per pound = 1.16637942857 g's

so 1 g of fat eaten = 1.166 g's gained? what happened to conservation of mass and energy?

emily889

Ow..

miss_jessiejane

darkguardian419

Yep... this is why I'm an Engineering Technician, not an Engineer. Same pay, less math.

scarletrayne19

As a scientist (who nearly failed physics) all I can say is when something is within two tenths like that I just shrug, chalk it up to some math error on somebody's part and say "close enough."

jackpotclown

\m/

FlowerFairy493

Wait what??? Lol

JoshLikesBeer

Rounding. Your math assumes that fat is precisely 9.0 calories per grams. It's actually slightly higher. Also, the number is different for different fats, and it can range from like 8.7 to 9.5, depending on how long the chains are and how saturated they are.

MagnumBurrito

3500cal / 9 = 388.88 grams of fat / lb

where's the 453.592 g's / lb coming from?

The_Enginerd

Adipose tissue (body fat) is not made of purely fat (pure lipids, what is counted in dietary fat). Human fat tissue contains about 87% lipids.

edit: Accounting for that, 9 calories/gram*453 grams/lb*0.87 =3547.

JoshLikesBeer

Rounding. Your math assumes that fat is precisely 9.0 calories per grams. It's actually slightly higher. Also, the number is different for different fats, and it can range from like 8.7 to 9.5, depending on how long the chains are and how saturated they are.

Edited to add, run your calculations backwards and solve for calories per gram, and you'll have a more precise number to work with.

wheird

Rounding. Your math assumes that fat is precisely 9.0 calories per grams. It's actually slightly higher. Also, the number is different for different fats, and it can range from like 8.7 to 9.5, depending on how long the chains are and how saturated they are.

This.

Hornsby

3500 is an estimate.
9 cals per gram is an estimate.

Voila!

brianpperkins

9 calories per gram of fat is an approximation which makes it impossible to know just how far off your calculations are. Physics is fine (until CERN finally fires up the LHC again next year and creates a singularity that restarts the universe at another bang).

marissanik

I'm just unsure of what you're trying to calculate here?? What.

KseRz

So bear with me here, I was just doing some brain thinking and realized something

if you eat 1 gram of pure fat, thats 9 calories. And to lose 1 lb you need to burn 3500 calories, or conversely to gain a lb you need to eat 3500 calories (above/below TDEE).

so 1 g of fat= 9 cals

9 cals divided by 3500 cals/lbs = 0.0025714285714286 lbs

0.0025714285714286 lbs times 453.592 g's per pound = 1.16637942857 g's

so 1 g of fat eaten = 1.166 g's gained? what happened to conservation of mass and energy?

http://www.myfitnesspal.com/topics/show/1376778-recomp-math

??

ETA: OPs Quote from link above.

So one lb of fat is as much as one lb of muscle its all mass right but that is where the mistake comes in. So let me go over the numbers

1 lb = 453.6g
1g of fat=9 cal
1g of protein= 4 cal
1g of water = 0 cal

This is stuff we all know, we also know that one lb of fat =3500 cal but 453.6g x 9cal= 4082cal. So how can this be right the numbers just don't add up right. The problem is fat is not all "fat", fat is made up of cells, that are mostly made up of water, but they hold a large amount of oil in them. So a lb of fat is made up of about 86% oil so that would about 390g of fat and 63g of water. Ok so more math now.

1lb=453g
390g oil x 9= 3510
63g water x0=0
390g+63g= 453g=1 lb

michikade

Technically speaking:

Lard - pure fat - is 905 calories for 100 grams - and even that figure is slightly rounded - so that fraction of a calorie per gram accounts for the variance.

BigT555

3500cal / 9 = 388.88 grams of fat / lb

where's the 453.592 g's / lb coming from?

453.592 is the conversion from pounds to grams. what you calculated is the inverse of what i calculated in my first equation;

3500cals/ lb divided by 9 cals = 388.88 lbs^-1. gotta watch those units

SuperVixen2B

Hahahahahaha! :laugh:

MagnumBurrito

grams / lb are off - 388.888 for fat

UsedToBeHusky

Um...

You need to show your work. What in the hell are you talking about?