Adding fiber to reduce net carbs

etompkinsdickey's Avatar


01 Oct, 2011 08:21 AM

Dear Dr. Rosedale,
I would like to know if adding a fiber supplement such as psyllium when eating carbohydrates such as fruit or starchy carbohydrates, will reduce the net carbs being eaten at the meal. For example, if you made a smoothie that had a banana or apple in it but also drank a psyllium drink before the smoothie, would that reduce the carbohydrates of the banana by the fiber in the psyllium drink? Would adding fiber be a way of helping to manage carbs to allow a greater daily allowance or permit one to offset the effect of the carbs when a person finds himself in a situation where he doesn't have a lot of control over the food that is being served?

Thank you.

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  1. 31 Posted by James Foreman on 16 Jan, 2019 03:24 AM

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    OK, I will add my caveat concerning how adding fiber does or does not reduce carbs in a meal. It is generally accepted when figuring the net carbs of a recipe to add all the carbs from all ingredients and subtract all the fiber from all the ingredients to determine the net carbs of the resulting dish. If like some have indicated adding additional fiber does not reduce the net carbs then why do we subtract total fiber of the recipe from today carbs to calculate the net carbs of the dish:

  2. Support Staff 32 Posted by Ken on 16 Jan, 2019 10:57 AM

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    Hi James

    The purpose of subtracting fiber from total carb is to find the total sugar content.

    • non-fiber carbs will eventually covert to sugar, which is not good -- so to find total sugar content, (even if it is said that no sugar is added) you subtract total fiber from total carb to find how much sugar actually there is.
    Total Carbohydrate is the: 
    dietary fiber and non-fiber combined
    Non-fiber will convert to sugar
    Fiber - is a carb, that does not convert to sugar
    Sugar - is a non-fiber carb
    Sugar Alcohol - is sugar
    Starches - converts to sugar


    Ken/   Rosedale Support Team

  3. 33 Posted by Tyler on 02 Mar, 2019 03:48 AM

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    It wouldn't reduce the overall net carbs of what you eat in the end, no. Using the above example of net carbs being the total amount of carbs from all ingredients in a recipe or dish less the amount of fiber from all ingredients is not correct. You determine the net carbs of a dish by adding all of the net carbs of all of the ingredients together. If you just add psyllium, you're just adding "0" net carbs to what you've already eaten.

  4. 34 Posted by Andy on 25 Mar, 2019 05:12 PM

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    Tyler is correct. I just fact checked him and he’s 100% on point.

  5. 35 Posted by Jonathan on 18 Apr, 2019 03:01 PM

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    Adding more fiber will not lower the net carbs. Here is an example, you eat a meal that has 30 carbs and 20 fiber, so that is 10 net carbs. You add 10 more fiber, but what happens if you now have a meal with 40 carbs and 30 fiber, STILL 10 net carbs. Because the finer adds to the total carbs.

  6. 36 Posted by Debbie ameche on 18 May, 2019 05:33 PM

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    If I add psyllium huskpowder to a baked potato can I reduce any of tha added fiber to get net carbs

  7. 37 Posted by Natasha on 22 Jan, 2020 08:57 AM

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    Fibre IS A CARB in itself and added to total carbs on labels...
    It is however not digestable by the body and therefor is not converted into sugar and then stored as fat.. we subtract the Fibre from total carbs as the fibre part will just pass through
    So logically adding Fiber will actually not reduce carbs in other foods consumed..... it cannot take hands of simple carbs and take it on the scenic tour through the digestive system and just pass through the body

  8. 38 Posted by diane on 06 Feb, 2020 07:28 PM

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    AHHH - I think I've finally got it! So when the label says 30 carbs, that is INCLUDING the original fiber -- and then they take off JUST THE FIBER AMOUNT to reduce the net carb. So adding fiber, as you say, just adds to the carb content. For a minute, I thought: oh I'll add chia seeds or flax seeds and trick the carb content. I guess you can't cheat reality.

    I never knew fiber counted as carbs! So this was a great lesson - and I'm glad I finally asked Google that question - Can you add fiber to lower the carb count. Now that I'm set straight I can understand the label more clearly.

  9. 39 Posted by Etienne on 27 Apr, 2020 12:57 PM

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    To 'cheat' net carb by adding fiber you would have to change the ingredients so if for example I felt like porridge for breakfast I would use 70g of oats for two portions of porridge. Adding milk, and no sugar would give me a net carb of over 20g carbs per portion. Instead I used 20g of oats, added water, psyllium husk, 15g of almond butter and some stevia for a total net carb of 12.5g. I got a wonderful two portions of porridge for a net carb intake of around 7g. It is not porridge per se but it managed to fool my brain into thinking it was, so that would be the 'cheat'.

  10. 40 Posted by Sabrina on 15 May, 2020 03:14 AM

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    Wow the things you learn from google !!! I needed to be educated on this ! Thanks

  11. 41 Posted by Nikki on 26 Jun, 2020 09:01 AM

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    It’s a very good question because it sounds like it should work. I want to say that if you put the psyllium in your smoothie and then you calculated the grams of carb in the psyllium you use, and then you reduce the fruit you use by that number of grams, you actually do get a smoothie with less of a net carb effect, but that said, 1 tablespoon of psyllium husk doesn’t even fully negate itself in carbs. It has 5 g of carbohydrate and 4 g of fiber. So you would have to reduce the amount of banana that you use by 4 g of carbs which is about a quarter of a banana. That’s based on 1 tablespoon of psyllium husk. But then, have you really lowered your carbs because you put the psyllium in there, or did you lower your carbs because you put less banana in? It’s actually the latter.

    So let’s say that you were trying to negate a piece of cake. It has about 20 grams of carb, no fiber. You take 4 tablespoons of psyllium, let’s say 2 right before and two immediately after eating it. No, it wasn’t cooked together, but it’s all in your stomach at the same time. You’ve raised your carb count to double what it was when you started, so now it’s 40, and you can only subtract/negate 4 g per tablespoon of psyllium husk, which means 16 g in total. So at the end you have actually raised your net carbs by four.

    Now that said, it might help you anyway; I’m not sure if that amount of psyllium husk might carry the cake out of your body before it can be absorbed, but even if that’s right, you’re starting to get into the kinds of practices that people with eating disorders have, which is usually the first step to actually developing one. Also, were you to make something like that a habit, you would lose vitamins and minerals. The bottom line is, you need to ingest foods that are made up of things that like psyllium husk are inherently self negating of carbs or mostly self-negating of carbs.

    So I’m not really providing a different answer than you’ve already gotten, I’m just explaining it differently.

  12. 42 Posted by Oren on 12 Jul, 2021 11:17 PM

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    You are correct! Adding high fiber food will reduce the net car percentage by blending its ratio with the current ratio.

    Even though the high fiber food has its own carbs, it still dilutes the Total Carb Ratio!

    I’m shocked that No one else understands that.

  13. 43 Posted by Bonnie on 14 Aug, 2021 09:21 PM

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    For Diane:

    ANY food that comes from a plant has carbs, including psyllium. How much of that is actually digestible is where the fiber comes in.

    As to the question of adding fiber to food, I’m still confused about this myself. I guess I could get a definite answer by using a gucometer before and after identical meals with and without the added fiber.I guess I would need to have nearly identical blood glucose. At the start of each.

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