There are THREE questions in here.
I am trying to locate an accurate source for the following questions.
There is a lot of misinformation floating around the internet, and I have been unable to find definitive conversion factors, instead I have found a LOT of made up make believe numbers.
For instance, carbohydrate is 4 calories and fat is 9 calories. One lb of fat is 454 grams = 3500 calories, so since if we divide 3500 calories(1lb fat) by 4 calores (1 gram carb) we get 875 grams of carbohydrate can become 1lb of fat.. <----But this is an INACCURATE CALCULATION. There is loss when converting carbs to fat via the de novo lipogenesis process.
I have also read that it takes 450 grams of carbohydrate to enter the cycle to create 150 grams of fat. Which means that it takes 1362 grams of carbohydrate put into the de novo lipogenesis cycle to create 1lb of fat. <----- I do not know if THIS # is backed up by real science either as the book I read it in did not site a source for this particular sentence.
One thing I would like to mention is that de novo lipogenesis is quite rare and only occurs when muscle glycogen is full, liver glycogen is full, AND elevated metabolism (from consuming carbs) can not keep up with oxidizing the glucose and there is no room to store it as glycogen.
My question for glucose therefore is - Once all three of the above criteria are met:
Q1: How many grams of carbohydrate does it take to generate 1lb of fat via de denovo lipogenesis?
regardless of the above criteria:
Q2: How many grams of protein does it take to make 1 gram of glucose?
Q3: How many grams of fat does it take to make 1 gram of glucose.?
A couple of points. Protein is not normally automatically partially converted to glucose, but once the process begins, how many grams of protein does it take to make 1 gram of glucose? For instance, if you flood your system with 100 grams of from protein, and 50grams of aminos get converted to glucose, how many grams of glucose does the 50 grams of protein produce? Its not 1:1
Human Fat(TFAs) to carbohydrate direct conversion does not exist in the human body. However, via a pathway involving glycerol, glucose IS created from fat oxidation. I have read that it takes the oxidation of 100 grams of fat to make 18 grams of glucose from 'leftover' glycerol, but, I can not find any hard scientific evidence of this.
just on Q3: How many grams of fat does it take to make 1 gram of glucose?
If you have not seen it already, this post by Chris Masterjohn may be of help? http://blog.cholesterol-and-health.com/2012/01/we-really-can-make-glucose-from-fatty.html
The answers (to Q1,Q2) depends on what kind of molecules you want to convert. There are carbohydrates (inulin, cellulose etc..) and amino acids which are not convertable to glucose with human enzymes... You can count the exact data from the molecule weight of your carbohydrates or the ratios of the amino acids your protein consists ...
Normally in the human body the protein to glucose conversion is very low. It's high just in extreme cases like starvation or diseases...
I always wonder about questions like this that get extremely mathematical with calories and grams and stuff. Human beings are not bomb calorimeters. I'm not saying the questions you're asking aren't important or worth asking, but I'm not sure they're completely answerable.
The human body is not a closed system wherein food substrates are oxidized 100% with no inefficiency or loss to the outside environment. The nitty gritty numbers game makes me nervous when it comes to food.