Author Topic: Calculating Percent Calories From Fat/Protein  (Read 5350 times)

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Offline magnetic

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Calculating Percent Calories From Fat/Protein
« on: July 28, 2011, 09:04:10 pm »
I am considering buying some grass-fed elk or deer, but I understand that the nutrient ratio is likely to be 90/10 (protein/fat), or thereabouts. I need more fat in my diet. How do I go about calculating the nutrient ratio if I were to add some elk/deer marrow to ground elk/deer meat? For instance, if I wanted to eat 1.5 lbs of 90/10 meat but end up getting 70% of my calories from fat, how would I figure out how much marrow I need to add to my meal of 1.5lbs. of 90/10 ground meat?

If I have 1 lb. meat, that's 454g. About 69% is water and ash. So 90% by weight is protein and 10% is fat, or 0.31*(454-45.4)g is protein and 0.31*45.4g is fat. In terms of calories, this would come to 0.31*(4cal/g)*(454-45.4)g + 0.31*(9cal/g)*45.4g = 505cal + 127cal. So %cal from fat and protein are 505cal/(505cal + 127cal) and 127cal/(505cal + 127cal) or 80% protein and 20% fat. This is too high in protein and low in fat for me. I would like to get about 70% of calories from fat.

So if F is calories from fat and P is calories from protein, and PCF is percent of calories from fat, then

PCF=F/(F+P)

For two foods (i.e. one marrow, the other ground beef), PCF=(F1+F2)/(F1+F2+P1+P2), where F1,P1 are fat and protein calories in the first food, F2,P2 the second food.

If we use the following data:

Game meat, elk, raw
http://nutritiondata.self.com/facts/lamb-veal-and-game-products/4635/2

Caribou, bone marrow, raw
http://nutritiondata.self.com/facts/ethnic-foods/8088/2

Then for 70% calories from fat and with 100g of ground elk (F1,P1):

0.70=(13+F2)/(13+F2+98+P2)

but P2=(1-0.967)F2=0.033F2 so

0.70=(13+F2)/(13+F2+98+0.033F2)=(13+F2)/(111+1.033F2)
=>
77.7+0.723F2=13+F2
=>
0.277F2=64.7
=>
F2=234 cal

234 cal/(9cal/g)=26g

So, if caribou marrow has a macronutrient content similar to elk marrow, and the ground elk I receive is about 12% calories from fat, then for each 100g of ground elk I need to add 26g of elk marrow to achieve 70% calories from fat. Is this correct?

Offline klowcarb

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Re: Calculating Percent Calories From Fat/Protein
« Reply #1 on: July 29, 2011, 01:48:08 am »
Use fitday.

Offline magnetic

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Re: Calculating Percent Calories From Fat/Protein
« Reply #2 on: July 29, 2011, 06:06:35 am »
Thanks, I will check it out. Nutritiondata doesn't have a lot of raw animal foods.

Offline magnetic

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Re: Calculating Percent Calories From Fat/Protein
« Reply #3 on: July 29, 2011, 06:43:23 am »
I remembered that the caribou marrow is 91% fat, not 100%fat. So I just need to divide the above figure:

26g/0.91 = 29g

Otherwise I think the analysis is correct. I looked at fitday but it seems very limited in raw foods. I think I just need to make a spreadsheet and use the above formulae.

Offline Josh

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Re: Calculating Percent Calories From Fat/Protein
« Reply #4 on: July 29, 2011, 11:47:13 am »
Fitday has all the raw foods like caribou marrow from the US nutritional database. You could also try making a spreadsheet. I did but couldn't get it to work for some reason.

Offline klowcarb

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Re: Calculating Percent Calories From Fat/Protein
« Reply #5 on: August 01, 2011, 04:29:25 am »
Fitday has all foods raw or cooked. I have no idea what you are talking about. I eat the majority of my VLC diet foods raw, and I use Fitday. I have only 2 custom foods because everything I eat is in the database.

Offline magnetic

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Re: Calculating Percent Calories From Fat/Protein
« Reply #6 on: August 01, 2011, 11:28:27 am »
Fitday has all foods raw or cooked. I have no idea what you are talking about. I eat the majority of my VLC diet foods raw, and I use Fitday. I have only 2 custom foods because everything I eat is in the database.

I couldn't find information for deer and elk meats, organs, bone marrow, etc.

Offline klowcarb

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Re: Calculating Percent Calories From Fat/Protein
« Reply #7 on: August 02, 2011, 11:22:36 pm »
You are not going to find marrow other than the caribou marrow. Just use estimates.

 

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