T Nation

Low-Carb Tortillas


#1

I got a package of "carb control" tortillas. They are high fiber and have a decent amount of protein, but the nutrition info doesn't make sense.

On the front, it says 7 g net carbs.

Then on the back,

Calories: 110
Fat: 2.5 g 25 calories
Total carb: 18 g
Fiber: 11 g
Protein: 5 g

Now if I add the fat (25 cal), 5 grams of protein and 7 grams non fiber carbs I get:

25 + 5 x 4 + 7 x 4= 73 calories.

I assume that they either wrongly calculated the 110 calories by using the total grams of carb, which would give 117 (OK considering rounding off here and there)

Either that or a lab determined the calories by combustion, in which case the fiber burns and releases calories like any other carb.

Just wondering, is the label wrong, or am I missing something?


#2

hey boner 18-11=7


#3

Yea I know. The 7 grams of carbs listed on the front is not the issue, its that:

25 calories from fat +
7 x 4=28 calories from carbs +
5 x 4=20 calories from protein=
73 calories while the info says 110.


#4

I've actually seen this before. I read somewhere, but don't quote me, that most manufacturers don't feel fiber has a full 4 calories per gram, so they take liberties in their calculations. Yes the overall calorie content includes the fiber, just not at 4cal/g.


#5

As far as I can tell from most of the nutrition labels I've seen, they normally do count fiber at 4 kcal/gram just like other carbs, even though the human body only absorbs some fraction of that.


#6

You must use total carbs, not net carbs in your calorie calculations.

fat 2.5 x 9 = 22 cal

carbs 18 x 4 = 72 cal

protein 5 x 4 = 20 cal

total = 114 cal (because fiber is usually rated a little less than 4 cals/gram that's probably why they have 110 cals listed.


#7

When they say "net carbs" on the packaging they are simply calculating the carbs that have an effect on blood sugar levels. That doesn't mean that the other carbs don't count as far as calories are concerned. So in that case the calories add up according to the f/c/p ratio.


#8

Thanks guys-I didn't think fiber had any useable calories at all.


#9

What's your definition of "useable"?

Food does not have "calories" in it. The calories listed are what it takes your body to break down that amount of food. Fiber is still somewhat broken down and calories are burned during that process, just not at a full 4cal/g.


#10

Actually the calories are the heat produced when the food is broken down-not what it takes your body to break them down.

Now I've been looking through several nutrition textbooks, and they all say basically that humans do not have any digestive enzymes capable of breaking down fiber-so I have to conclude that pure fiber releases no calories in body, but does in a bomb calorimeter which is probably what they used to assess the calories of this food item.


#11

Technically what you said and I said is the same thing. The heat is generated when you break down the food. You can't do one without the other, so they are basically the same process.

I did not know that. Doesn't it still take energy to physically pass and route the fiber through the body? I can't imagine there is no thermal effect at all. Seems too absolute to me.


#12

A lot of the low carb tortillas are filled with trans fat,so look around for that.


#13

Does anyone know how they determine the amount of cals/fats/prot/carbs in a food product? Is there a machine or something?


#14

Yea it takes energy to break down food, and energy is released from food. I read that it is believed that because fiber acts to scrape away intestinal mucosa that it takes energy from the body to replenish this mucosa.