Need some math insight

(Greg) #1

I’m well on the trek to weight loss, at 17 pounds in 6 weeks. I use MacGourmet Deluxe to analyze my recipes and crunch the nutritional information for me. It works really well, but it doesn’t give “Net Carbs”. Instead, it gives “Carbohydrate, by difference”. I’m not sure what this means even though I’ve looked at the definition:

How is Carbohydrate, by difference determined?

Carbohydrate is determined as the difference between 100 and the sum of the percentages of water, protein, total lipid (fat), ash, and, when present, alcohol. Total carbohydrate values include total dietary fiber.

Total carbohydrate by difference = 100 - [water, protein, total lipid, ash and alcohol in g/100g]

Does anyone know if, when given “Carbohydrate, by difference” and a value for fiber, sugar alcohols, etc., if carbs by difference is treated like total carbs and therefore, those values for fiber, sugar alcohols, etc. aresubtracted off yielding Net Carbs?

I’ve never seen carbs by difference used anywhere except within this software, and the tech support can’t answer my question.

Thanks in advance!
Greg

(bulkbiker) #2

Can you not compare the result with something you can verify elsewhere… say enter 100g of some specific food like cauliflower then see what it gives you for carbs then compare with a food supply website that gives carbs per 100g of cauliflower?
I’m in the UK so our supermarket sites give nutritional info per 100g.

(less is more, more or less) #3

There’s a lot of funny math to net carbs. All of which is why I stick to total carbs.

(Greg) #4

I did try the comparative method as follows from https://nutritiondata.self.com/ & the UDSA nutrition websites, which I figure should have some pretty accurate info…Here is what I found comparing the information for 100g of white potatoes, raw, flesh & skin.

The Nutritiondata website is pretty simple:
Total Carbs (Fiber + Starch + Sugar) is 2.2 + 15.4 + .8 respectively = Total Carbs of 18.4.
Net carbs are 18.4 - 2.2 = 16.2 --OR-- 15.4 + .8 = 16.2.
So their data works either way, add starches and sugars or use total minus the fiber content.

The USDA website information is not so simple. They report “Carbs, by Difference”…
they do not report Total Carbohydrates, but do report the three components of total carbs as above so
one can calculate total carbs, and thus net carbs as follows:

Total carbs are 2.4 fiber + 13.49 Starch + 1.15 Sugar = 17.04.
Net Carbs should be 17.04 - 2.4 = 14.64 --OR-- 13.49 + 1.15 = 14.64.

Yet, they report “Carbs, by Difference” to be 15.71, which is less than total carbs but greater than net carbs.

I am trying to figure out if I need to subtract the Fiber value from the Carbs, by Difference value.

Leave it to the US Government to gum up something so simple, and the software package I use to pull data from it…wow…

Thanks for any input on this, it’s really got me perplexed!

(Banting & Yudkin & Atkins & Eadeses & Cordain & Taubes & Volek & Naiman & Bikman ) #5

You can use carb by diff as total carbs. To paraphrase a former professor of mine, “Only God knows the true carb count of anything.”

(Running from stupidity) #6

Spot on.

OP, any reason to not just switch to something like Cronometer? It’s extremely easy to understand.

(Greg) #7

The software I have is very efficient and accurate at calculating recipes, allowing for scaling recipes and adjusting serving sizes and the like…plus, I have a LOT of recipes and nutritional values entered into the database. I guess the safest bet is to treat the carb by difference as total carbs as previous post suggests…no one can seem to clarify this. Only the government could use such a confusing and mundane value.

(Banting & Yudkin & Atkins & Eadeses & Cordain & Taubes & Volek & Naiman & Bikman ) #8

It’s funny, because the government also mandated labels on things to contain the carb levels. This is why I suggest treating the government terminology as the same as the general terminology. I think “by difference” just means they figure the easy stuff (fats, proteins, alcohol), burn it in a calorimeter, and back out the carbohydrates. by subtracting the easy stuff. The other method for determining carb number is using established numbers of ingredients, and working it up. But those reference numbers were all determined by this government or that government, by difference.

The government likes it’s terminology. They have a consumer friendly version for labels (which they mandate standards for), and a scientist friendly version they use internally.

Only home users could read the government documents and get hung up on the minutiae of the terminology.

-A Government Wonk.