So What Are Net Carbs?

[PilotGal]

So what are net carbs?

Even the FDA says the term is confusing. Net carbs are the total carbs minus the indigestible carbs. But experts say if you're counting carbs, even the good carbs count. So you see, even labels can be confusing. And not only to consumers.
The FDA says they are looking at the issue of net carbs very carefully and are in the process of determining whether it is a fraudulent term.


http://cbs2.com/specialassign/local_story_036200059.html

[blue4lemon]

net carbs are carsb minus fiber and sugar alcohols or other carbs that low carb diets don't recognize as carbs. the confusing part is that some sugar alcohols do affect blood sugar some.

[angeljandy]

Personally I have a problem with SA, it causes me to stall, so I've been avoiding it. Some People have good luck with it.

[PilotGal]

My take on all this rhetoric is, if it's not a pure food, it's not worth putting in my mouth.
Only franken food I indulge in about 3X a week are the Publix SF fudgecicles, and I only eat one stick.
Fair enough?

[Kristine]

Rubbish. :thdown: I love how they invoke Dean Ornish, since he has a "nutritional clinic." They don't mention that he's one of the most anti-LC people out there!

All of these foods are suppose to be low in carbohydrates.

Well, they ARE pretty low in sugar/starch carbs. Did they even subtract fiber? They don't say, but it doesn't look like it.

[tom sawyer]

What I'm mad about is, why is Burger King ripping me off? I paid for those carbs, I counted those carbs, I WANT THOSE CARBS!

[Sona]

This was raised on another thread, but I don't believe it's been pursued--and it's worth pursuing for ideas, theories, etc.:

Putting aside the turmoil going on right now with Atkins et al. in potentially reformulating the "net carb" concept, and focusing on what has been the typical MO with net carbs:

Why, if we are able to subtract the fiber from the total carb count to arrive at the acceptable number of carbs we can take in within a day--under the assumption that the fiber is not digested--are we then, at the same time, counting the number of calories those fiber carbs constitute as part of our daily caloric intake?

To calculate that a certain food item is being properly broken down, according to the nutritional label, we should be able to multiply total number of carb grams (which includes the fiber carbs) by 4, total number of protein grams by 4, and the total number of fat grams by 9, and arrive at the total number of calories per serving listed at the top of the nutritional label. Same with the fitday tallies.

That means, when we calculate how many calories we've taken in in a day, we are looking at total carbs including the fiber carbs, yet we are subtracting the fiber carbs from our carb gram totals.

Isn't this somewhat inconsistent in terms of how we are assessing/calculating the numbers that represent how we are progressing on our WOE?

If it is not, if there is some other reason that the fiber carbs don't need to counted in terms of "digesting/burning" them, but the calories they represent do need to be counted, what is the reason?

Ideas? Thoughts?

Best, Sona

[Nancy LC]

Well let me see if I can remember this from my low fat days... been so long now.

Insoluable fiber isn't counted towards the calorie count on a product because you can't digest it, but soluable fiber is. So the number you see that says "fiber" is actually some fiber that contributes calories and some that doesn't.

[db81971]

What I'm mad about is, why is Burger King ripping me off? I paid for those carbs, I counted those carbs, I WANT THOSE CARBS!



Oh no! What about Burger King??? I eat there at LEAST once a week.....

[Sona]

But, Nancy, aren't we going along subtracting whatever number is listed under "fiber" (never mind sugars or anything else; just where it says "fiber") from the total carb gram count? We aren't told which is soluble and which is insoluble, at least not on the label there.

So does this means that we are then actually (perhaps) subtracting some soluble fiber grams--carb grams that actually are being digested or, as you say, are contributing to the calories we will ultimately be burning?

Am I getting what you meant to say correctly? That soluble fiber should not be considered part of the "net" concept, because it actually gets digested (while the concept of subtracting fiber carbs is based on their indigestibility)?

And if that is so, how are we then to know this from any nutritional label, when all it says is "fiber" (that is, there's no division into "soluble" and "insoluble")?

[fatburner]

Well let me see if I can remember this from my low fat days... been so long now.

Insoluable fiber isn't counted towards the calorie count on a product because you can't digest it, but soluable fiber is. So the number you see that says "fiber" is actually some fiber that contributes calories and some that doesn't.

I'm totally confused now. I was under the impression that soluble fiber is not digestible at all. I just thought it was just better 'quality' in terms of the purported benefits of fiber. As regards S.A's the G.I of the various types is well established, as is the proportion that can be metabolized (contribute calories). Erythritol is streets ahead of the rest - 0 G.I. .2 calorie/gm. But mannitol isn't too bad either. Just be wary of mannitol. The name sounds and looks very similar to maltitol, which is glycemically and laxatively a very nasty substance and features in a lot of 'low carb' products.

Here's an excerpt of a web page about the glycemic effect of sugar alcohols put together by Mendosa (the diabetes guy). The first number is the glycemic index. The second is the calorie value per gram. It's very revealing about the world of difference between polyols. IMHO maltitol syrup has no business being considered low carb at all, and any 'L.C.' food that contains it is a joke.



[Quote: David Mendosa]:


Glycemic Index and Energy Values of Polyols Polyol GI (glucose=100) Calories/g :

Maltitol syrup (intermediate) 53 3
Maltitol syrup (regular) 52 3
Maltitol syrup (high) 48 3
Polyglycitol (hydrogenated starch hydrolysate) 39 2.8
Maltitol syrup (high-polymer) 36 3
Maltitol 36 2.7
Xylitol 13 3
Isomalt 9 2.1
Sorbitol 9 2.5
Lactitol 6 2
Erythritol 0 0.2
Mannitol 0 1.5
Source: Livesey, op. cit., pp. 179, 180.
Not all the low-carb gurus are on the polyol bandwagon. Dr. Richard K. Bernstein, a noted endocrinologist who wrote Dr. Bernstein’s Diabetes Solution (Boston, Little, Brown, revised edition 2003) says on page 139 that, “Some [sugars], such as sorbitol…, will raise blood sugar more slowly than glucose but still too much and too rapidly to prevent a postprandial blood sugar rise in people with diabetes.”

Confirmation of Dr. Bernstein’s position comes from a correspondent, Mary Lu Connolly. She wrote me in January that she has type 1 diabetes and has tried to reduce her carb intake by purchasing the low-carb foods now available. “What I have found is that these foods (especially breakfast bars) cause major rises in my blood sugars hours after eating. Can you explain what is happening?”

At the time she wrote I couldn’t explain it. Now, it’s clear that the culprit is probably maltitol or maltitol syrup. For example, Atkins Nutritionals Peanut Butter Cups have 11 grams of maltitol per serving. The “Net Akins Count” is 2 grams. Atkins Praline Sauce Duet has more maltitol syrup than anything else — 19 grams per serving. The net carbs count is 2. Or you could buy the Atkins Endulge Caramel Nut Chew Box, advertised as having 2 grams net carbs per serving. Yet a serving has 15 grams of maltitol.

Each of these examples come from the Atkins.com. None of them indicate that the glycemic index of one of their primary ingredients — maltitol — is higher than that of pearled barley or kidney beans.

Sugar alcohols do vary considerably in their glycemic indexes. It’s complicated, but they aren’t all created equal.

What Is the Impact of Glycerin?
Glycerin (or glycerine) is a liquid byproduct of making soap. It is wonderfully versatile and has been used as a solvent, antifreeze, plasticizer, drug medium, and in the manufacture of soaps, cosmetics, inks, lubricants, and dynamite. Now it is also used as a sweetener.

Atkins Nutritionals says that glycerine is another carbohydrate that has “a minimal impact on blood sugar.” Dr. Thomas Wolever, professor and acting chair of the department of nutritional sciences at the University of Toronto, confirms this in personal correspondence with me. He also heads a company, Glycaemic Index Testing Inc., which has ascertained the GI value of hundreds of foods.

“We did a study on glycerine at GI Testing, but the data don’t belong to me so I cannot publish it — except it was published in abstract form — and up to 75g glycerine had a negligible effect on blood glucose and insulin in normal subjects.’ He cites his article, “Oral glycerine has a negligible effect on plasma glucose and insulin in normal subjects” in Diabetes 2002;51(Supplement 2):A602. Some others believe, however, that it might have a greater impact on people with type 2 diabetes who have overactive livers.

What Is the Impact of Polydextrose?
Polydextrose is another carbohydrate. It is used primarily as a bulking agent for the preparation of calorie-reduced foods. Atkins Nutritionals says that polydextrose has “a minimal impact on blood sugar.”

Again, Dr. Wolever can confirm the Atkins claim. ”I don’t think polydextrose is available in the small intestine at all,” Dr. Wolever tells me. “If that is so, it has no effect on blood glucose.”

A recent study lead by Zhong Jie of Rui Jin Hospital in Shanghai, “Studies on the effects of polydextrose intake on physiologic functions in Chinese people,” confirms Dr. Wolever’s belief. This study, reported in the American Journal of Clinical Nutrition, Vol. 72, No. 6, 1503-1509, December 2000, concluded that “polydextrose had no significant effect on blood biochemistry indexes” include the glycemic index. Their study confirmed “that polydextrose is nonglycemic.”

Conclusion?
Dr. Atkins and the vendors of low-carb products are correct that not only fiber but also glycerin and polydextrose have little or no effect on blood glucose. The story with sugar alcohols, however, is different. One of the most commonly used sugar alcohols, maltitol and its syrups, does have a considerable effect on blood glucose. Two sugar alcohols, erythritol and mannitol, have no effect, and four others have some effect.


You need to check which sugar alcohols are used in any low-carb products you buy. Just like different carbohydrates affect blood glucose to different degrees, so too do some sugar alcohols. [Quote]

[Samasnier]

How much fiber are you consuming a day that you need to worry about subtracting fiber calories?

[Sona]

Samasnier, it isn't (I suspect) that there would be that many fiber calories to subtract (maybe 40 to 50? who knows; never added them up separately). But I am currently carb cycling, and on a carb down day, 40 to 50 extra calories (on 1200) that can be factored out would mean an extra 1/2 oz. of (0 carb) brie cheese, for instance. And that would be welcome! :)

Best, Sona

[tom sawyer]

Are the calorie values on a nutritional label not corrected for the fiber content? I know they determine them using a bomb calorimeter which burns everything completely, but I would assume that they would make this correction, especially if a food contained a large number of calories.

In fact, I think they probably already do this. Otherwise, my dose of sugar-free metamucil would have a significant number of calories, whereas the package lists almost no calories, as it should be.

I suppose the question would be, is this correction always made? And is soluble fiber included, or only insoluble? You are right, if you are ingesting 30g of fiber per day as recommended, then that would be as much as 120 calories. That would be 10% of a 1200cal diet.

On the other hand, it is a pet peeve of mine that people think they are calculating calories to the nearest 1 or 10. Let me tell you folks, when you use a calorie value for a food it is quite possible that it is off by 10-20%. Especially the fresh foods, there is just a certain amount of biological variation inherent in such products. All broccoli is not created equal. So don't get your shorts in a bind over a hundred calories.

[Sona]

Tom, I'm never so rigid that I would expect perfection in calorie calculation--on anyone's part (including mine). But if I start from that premise, I can easily get sloppy in my own preparation (not just calculation) of meals ("Oh, what the hell, it's probably off by about 10% anyway--don't get so fixated, just eyeball it"). And for someone with my leanings (give me an inch and...), it's better not to start from an acceptance of imprecision.

I don't hold the companies accountable for a margin of error, but I'd rather not take error into account up front. This may not make sense to someone who has a well-balanced (and
-practiced) approach to a particular WOE, but it is best for me--at least until I've been at this long enough to know how to relax with the way I eat. :)

Oh, yeah--and as for whether or not a food manufacturer (or fitday or whoever) already calculates out the appropriate fiber calories...you're right, it's hit or miss. I've done the math on different items, and sometimes the calories match with all carbs (including fiber) and sometimes it would seem the cals for fiber carbs have been subtracted. Not very reliable. So I don't really know what's going on with that.

Best, Sona

P.S. What's a "bomb calorimeter"?

[tom sawyer]

A calorie meter (calorimeter) measures calories in a fuel sample, by burning it and measuring the heat given off. The "bomb" part, is due to the fact that it has a little metal container that you burn the material inside. It is first sealed, then you fill it with pure oxygen prior to ignition, so everything burns completely. When you ignite the stuff and it burns, the heat and pressure remain in the little "bomb". The way the temp increase is measured, is by having the little vessel in a water bath and measuring the water temp.

Add too much fuel, and the little container could become an actual bomb. Ours can hold no more than 1 gram of material. We happen to have a few of these instruments in the lab where I work. We use them to measure the heat of combustion of fuel samples.