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What Are Net Carbs? Effective vs. Non-Impact Carbs

Carbs are one of the most controversial topics when it comes to the keto diet. If you’re just starting your keto journey, learning about carbs is vital as they are one of the main things you’ll be constantly on the lookout when making your food choices.

The idea behind net carbs is that certain carbohydrates don’t need to be tallied in your total carb count for the day.

In other words, it’s not just about your carb intake — it’s about what kind of carbs you’re consuming.

In this article, you’ll learn which carbs can keep your blood sugar stable, whether or not calculating net carbs is worthwhile, and how to calculate net carbs if you want to.

Impact Carbs

An impact carb is any carbohydrate type that has a high impact on your blood sugar level. These carbohydrate varieties are known as high GI (or high glycemic index[*]) carbohydrates and they break down rapidly into glucose, which then makes its way to your bloodstream.

When high-GI carbs enter your bloodstream — unless they are immediately used for physical exercise — they typically contain more energy than your body can successfully use in one go. And everything you don’t use as energy gets stored — sometimes as glycogen in your muscles and liver, but mostly as body fat.

Impact carbs can be very damaging to your health (and waistline) when you consume them regularly in high amounts.

This is why it’s so important to calculate macronutrients specific to your goals, activity level, and health history. You can calculate yours here.

Non-Impact Carbs

Now, on the other hand, non-impact (or low-impact) carbohydrates are low-glycemic and digest at a much slower rate. Due to this prolonged release of glucose into your bloodstream, insulin spikes are less likely and you’ll experience more sustained energy levels.

It’s the overconsumption of high-GI carbohydrates that are presumed to cause many of the negative health conditions like obesity and type 2 diabetes — hence, the rise of nutrition plans like the keto and Atkins diets. These plans help your body make the switch from being carb-dependent to being fat-dependent.

Creating a Healthy Carb Balance

The main goal in a low-carb or keto diet is to replace most carbohydrates with healthy fats and protein. But it’s also important to know exactly when you can have high-impact carbs versus low-impact carbs.

You can use high-glycemic carbs, for instance, to help support your workouts or for sports performance.

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However, for anyone following a relatively sedentary lifestyle, the energy from high-GI carbs isn’t necessary.

If you think your workouts warrant a few extra carbs, you might want to check out a cyclical ketogenic diet or a targeted keto diet.

How to Calculate Net Carbs

When it comes to carb counting, one thing that can get a little confusing is the “net” carbohydrate situation. Don’t worry, though — it’s not nearly as difficult as it sounds.

Net carbohydrates are what you’re left with after subtracting the grams of fiber per serving from the total carbohydrate amount per serving. For example, if an item has 20 grams of carbohydrates and it contains 8 grams of fiber, then the amount of net carbs the item contains is 12 grams.

This is a great way to measure the potential “damage” an item could cause you. Since fiber is essential for the successful internal function of the body and contains no calories because it’s not absorbed, what you’re left with is the true caloric content and carbohydrate content.

The keto diet is based on this system, and it allows you to successfully gauge whether you’re taking in enough fiber and eating the right kinds of carbs.

High-GI carbs are typically very low in fiber, so you’re mostly consuming sugar and not anything that will serve a practical purpose in your body when you eat them. You really want to be sure the carbs you eat for energy have a low “net worth” once the fiber has been removed.

Soluble vs. Insoluble Fiber

Fiber is a type of carbohydrate that, unlike other carbs, can’t be broken down into digestible sugar molecules. Therefore, dietary fiber passes through the intestinal tract relatively intact. It is crucial for optimal digestive functions and overall health.

There are two types of fiber:

  • Soluble
  • Insoluble

Soluble fiber is the type of fiber that can be diluted in water, creating a gel-like substance that will make you feel fuller for a longer period of time (helping to promote weight loss).

This happens because this substance slows down the process of absorption of food in the body. Even though it contains a small number of calories, it doesn’t seem to affect your blood glucose levels. Soluble fiber also feeds your gut bacteria, ensuring a healthy microbiota [*].

Insoluble fiber, on the other hand, is the fiber that does not dissolve in water, has no calories, and its function is to help you have healthy and regular bowel movements.

When buying processed goods, reading food labels is extremely important as some manufacturers may place a type of processed fiber in their foods, called IMO.

IMOs or Isomaltooligosaccharides can occur naturally in foods like honey or fermented foods like miso and soy sauce. When manufactured on a commercial scale, IMOs are processed from cereal crops like wheat, barley, oats, tapioca, rice, potato, pulses (peas, beans, lentils), and others.

Studies on IMOs show that they may raise blood sugar levels[*]. Even though the FDA is petitioning to grant them fiber status, the EU prohibits health claims for oligosaccharides, so take that into consideration when reading nutrition labels.

Learn more about the almighty fiber in this podcast episode with Dr. Michael Ruscio.

Sugar Alcohols and Carb Count

Sugar alcohols, also known as polyols, are comprised of sugar molecules and alcohol molecules. They do not, however, contain ethanol, the compound that makes you tipsy after a few drinks.

Sugar alcohols are naturally occurring in a vast number of fruits and vegetables but they’re mostly used as alternative sweeteners. The most well-known ones are sorbitol, erythritol, xylitol, and maltitol and they are commonly found in sugar-free foods.

Even though they are considered alternatives to sugar, keep in mind that these polyols do contain calories and some of them might affect your blood sugar and insulin levels.

Learn how to calculate sugar alcohols net carbs here.

Calculating Net Carbs in Whole Foods

When your goal is to lose weight and your tool of choice is a low-carb diet like the keto diet, whole foods are your best friend. Why?

Because to calculate net carbs in whole foods is the easiest thing in the world.

As whole foods are comprised of a percentage of naturally-occurring fiber, all you have to do is subtract the grams of fiber from the grams of total carbs. And voilà!

Take an avocado, for example. It’s one of the most important whole foods in a keto diet not only for its dense nutrient content, but also for the immense quantity of healthy fats it contains (such as omega-3s and omega-6s).

A medium avocado contains:

• 21 g fat

• 2.7 g protein

• 12 g carbs of which 9.2 g is fiber

• 12g carbs – 9.2g fiber = 2.8 grams of net carbs

Here’s a great tool provided by USDA, which contains all the nutrition information about thousands of whole foods and more, to help you on your keto journey.

Now that you know the difference between carb types, you can use this information to integrate them into your daily diet and form a plan that will keep you in ketosis.

Completely removing any nutrient from your diet is never the best way to ensure overall vitality. However, maintaining a balance, especially if you’re very physically active, is the key to getting your nutritional needs met.

Learn more about how to start a keto diet and get the detailed, scientific-based information you need for a healthy lifestyle.


41 thoughts on “What Are Net Carbs? Effective vs. Non-Impact Carbs

  1. Hello, I’m hoping you can answer my question. I’m trying to start a keto diet. My confusion is this, after using a keto calculator, I’m being told 20g carbs a day. Well veggies and fruits have carbs. Are they just referring to things like ,potato, or breads? Or am I suppose to count all carbs? Cause this seems completely incomprehensible! There is no way to only invest 20g carbs a day and live! Thank you for your help.

    1. You count all carbs but if you think about it like this. You can have way more broccoli and cucumber than say bread for your 20 grams of carb. Veggies and salads will provide you with the carbs and fibre in a way that bread can’t

    2. You can do it I eat between 15 and 20g a day. I am a vegetarian on a Keto diet! Dairy like cheese and butter is what I live on lost 15 pounds in 2 week. And I am now just finding out about net carbs !? so I could be eating much more!
      Your body starts to get its energy from fat instead of carbs. I know some people who eat less then 5 g a day.

      1. Hello! When you refer to eating 15 to 20g of carbs a day do you mean net carbs or just carbs? Hope this makes sense as I’m new keto and wanting to start.

    3. Hi there. I’m a couple of months late in responding to your comment but I’ve been eating less than 20g of carbs for 11 months and have met my weight goals as well as have had health improvements. When you eliminate the high carb veggies, you are still left with many beautiful, tasty veggies to choose from. And the high healthy fat intake keeps you very satisfied.
      You may have already found your groove. But if not, good luck on your healthy eating adventure!

    4. Oh heavens yes you can totally live off of 20 grams. I come from a province that diets were based off of meat and potatoes. I thought the same thing about what you said however I can say it was a total lack of understanding on my end. I started off at 295 and after 6 months of strict Keto and yes 20 grams is my total carb count daily and loving it. There is soooo much variety available. I’ve invested into Keto coaches and with a bit of success I dropped off Keto. I relied on someone and didn’t educate myself. I had meal plans etc but honestly I didn’t commit. I invested a ton of money into the coaches and meal plans and food it was disgusting. I ended up walking away for 4 months. What I did do was purchase two of the best books in my opinion that educated me on everything and also included meal plans and so much more. It’s by Leanne Vogel called The Keto Diet. In this book there are soooooo many meal plans and not boring recipes. I love ethnic foods and fruit as well as veggies and I was blown away. Just today the meals I had were so filling and I only had with all that 12.5 net carbs. There is honestly so much variety and again coming from a province that has access to orchards and gardens I thought it would be hard but no not at all. In fact I found out through this whole adventure what fruits and veggies my body really didn’t like or did like.

      I hope this helps. Good luck and have fun with it. Seriously there’s a lot to learn and just be dedicated to you.

    5. I have been on the ketogenic diet now for about 2 weeks and it is hard but you can do it on only 20 net carbs a day even 20 total carbs a day.. I am a severe diabetic and this diet has greatly helped me get off over 125 units of insulin a day.. Yes you count everything.. I weigh how many carbs per gram of food I am allowed. So I may have a no carb sugar free energy drink in the morning with one serving of nuts 2 carbs.. Lunch may be 1/2 of can of Tuna White packed in water with mayo, mustard, 24 grams of cut yellow onion and one dill pickle on cucumber slices.. that lunch comes to 6 carbs.. 3.9 carbs for the cucumber and 1 for the onion and 1 for the pickle.. Then dinner maybe 1 cup of tomato soup with 25 grams of fresh spinach and romano and parmesan cheese in it. Now this one is higher as the tomato soup has a whopping total of 19 carbs for one cup and the spinach has 1 carb. So I get as close to 20 carbs a day as I can but you can always have the foods free of carbs which are meats, hard cheeses, eggs. I find if I have a craving for potato chips that crispy bacon is a great substitute. Remember Fresh is best but if you purchase processed food items count the total and net carbs to help you with your diet goals..

  2. I am keeping calories below 1300, my carbs 25 or below, taking MCT oil, got some electrolytes (mineral additive) for the leg cramps and I’m recording and strictly following the allowable foods. No cheating. However, I haven’t lost a nanogram of weight for the past 2 weeks. The constipation caused my this strict low carb is making me feel really uncomfortable. I want to stay with it but I am getting really discouraged. I don’t know what needs to change other than that I obviously need more fiber. My diet has become boring (can’t face another egg)and frustrating to be so strict and see NO results at all. I have been out of Keto for the past couple of days too. What should I consider or just try a different diet?

    1. It’s funny that you say you have trouble with constipation because I had the opposite effect. Are you drinking enough water? Because it is a must on the Keto diet. It may be the differences in our digestive systems, but it may be that you are not eating enough vegetables as well. I eat a LOT of leafy greens, cabbage, and cruciferous vegetables like broccoli. I also enjoy snacking on nuts, seeds, and spicy pork rinds. I like to spice up my food with garlic, siracha sauce (chili), and cayenne pepper. I also drink a lot of tea, and there are some brands that offer a laxative effect. I know everyone has different preferences, but I hope this helps.

    2. I find analyzing ever darn thing going into your mouth is a pain in the neck, and other anatomical places. Forget it. Just think to eat as close to the natural state as you can. White/brown sugars aren’t natural. They’ve been processed. Breads…processed. Ice Cream…processed.. What’s funny is once you find your personal ‘go to’ foods, eating limited carbs becomes second nature. I always worry about not feeling full, but it hasn’t happened in the month I’m adjusting my diet. Put some walking into your day, and before you know it, you’ll see a difference when you look at the scale, and you won’t even feel hungry. You know you’re getting healthy.

  3. Besides yoghurt what are some low carbs ( under 20 net carb) ingredients? I read about leafy green veggies but even a small amount adds up !

  4. I do about 100 carbs a day. I lose quite a bit of weight in a weeks time. The trick is to eat salads with your meals. If you eat a burger with a bun eat it with lots of salad. If you eat a fajita make sure you load it with salad. Try to add a hand full of pistachio nuts as a snack. Also add sugar free candy to help with your sugar cravings. This all works for me and also try to limit red meat as much as possible. Don’t stay away from it, but try to limit it to once or twice a week.

  5. I am very frustrated I have been on Keto now for a month. I try so hard following all rules. I make the fat bombs etc. I use the urine sticks and I am always in the small amount. Never in moderate or large ketones. I have had no bread pasta or anything white basically. I have lost 0 weight. I am very discouraged. I thought maybe I was eating to much protein and I cut down and increased the fat. I have had no real sugar either only Splenda as I hate stevia. I am not sure why I can not lose weight. Does anyone know if there are any medical reasons a person would not lose weight on this diet?

    1. Your age might be a factor. I am in my mid fifties and was eating very well before I started keto and it took me more than 3 weeks to see ketones and results on the scale and it was only a few pounds. My daughter who is 30 had lost 9 lbs during the first 2 weeks. She ate a lot more eggs and bacon than I did the first 2 weeks also. I think I might not be eating enough especially when I do intermittent fasting. Now I am now writing everything down. I also had constipation issue which I never experienced before. When I saw the info about net carbs I began to add fibre foods and it got a little better. I drink lots and I am also taking magnesium Bisglycinate. I hope that I am turning the corner. Although the weight loss is minimal I see my body being slimmer and clothes are finally fitting better. I hope you keep at it longer.

  6. Lots of comments about constipation on the Keto diet. You have to really up your vegetables that contain high soluble fiber. Plus your water (with added sea salt) consumption needs to go right up too. Add at least another 500-1000ml to your regular amount. Intermittent fasting is also another usual tactic to help with constipation. Fat digests much slower than carbs, hence why you feel fuller for longer. You need to give your body time to process the extra fats you are now consuming on the Keto diet.

  7. I’m with Nett! How come it doesn’t say “net Carbs” when saying your allowance is 20 grm a day?! I’m guessing it’s net, but it would sure be nice to know for sure!

  8. Hi all, I love a drink, used to be lager but I have changed to white wine and soda. I’m guessing this is ok ish??

  9. I have started this keto diet it is amazing how much better I feel. however the last couple of days I feel tired and have had a problem burping alot. Is there something I may need or I may be doing wrong?

    1. Hi Linda, burping could be a sensitivity to a certain type of food you are eating. We encourage you to track your food and see if you can find a pattern. Depending on when you started keto, you could be experiencing keto flu or not getting enough fluids/electrolytes.

  10. Well. I have read all of the stories and I am happy that I have been on Keto for about 4 months and lost about 40 or 45 pounds. It’s a little different for me. I had a stroke last year and I have to be careful which veggies I eat. The leafy stuff will interfere with the blood thinner “Warfarin”. Watching my carbs have help me working on getting healthy. I start walking to help lose weight, but it took a long time to get in the right mind. Last year in July I checked into the hospital because of a issue with breathing and coughing. Well, they weight me, and I was a whooping 342 pounds with clots, lots clots. Anyway, it’s been 13 1/2 months and I was weight at the doctors office last week and……… I am at 235 pounds. With Keto- walking/pedding machines went from 1 to 2 miles a day to up to 20 -25 miles a day, more or less. I feel better now than ever before. Thank you Dr. Anthony Gustin, D.C., M.S.! What you have done has help me immensely. I cant tell you how this has changed my life. One more thing, according to cardiologist, if I get to between 220 and 224, I could lose my CPAP. Hurray, Wooohoo!!!
    Thank you again!!!!!!!!!

    Derrick D.
    Age 52

  11. okay so I just started this Keto diet and I’m still confused on net carbs and total. If I eat 20 net carbs for the day will that still keep me in ketosis or do AL carbs have to be accounted for?

    1. Hi Paola, when you’re starting the keto diet and experiencing a plateau, use total carbs. And once you’re in ketosis, you may count net carbs.

  12. Keto is to count All carbs not net carbs. I find Keto very easy when done right. I was on strict keto for 9 months, I ate chicken, fried wings, tuna with mayo, salmon with butter, burgers with cheese….basically any meats and eggs, then add cheese and fats like butter, oil, mayo!! NO CARBS of any kind until you hit your goal. Then slowly introduce green veggies. Take a fiber cap a day for constipation. Multi vitamins and I do a protein powder with 0 carbs so I get the sweet flavors. I lost 109 pounds in 9 months!!! That was 12 years ago!!! Now I alternate strict keto 3 weeks out of every 3 months. The rest of the time I eat veggies with all meats and fish. I cheat every Sunday ( one day a week, one meal) with anything I want.

  13. Carol, I read something today on Splenda and sweeteners causing a person to not be able to reach they’re weight goals, you may want to check it out, hope it helps

  14. I am new to Keto. I am not allowing carbs at all. Am I setting myself up for failure. Is diet soda Bad on Keto?

    1. Completely removing any nutrients from your diet is never the best way to ensure overall vitality.
      You can still allow carbs on your diet.
      However, maintaining a balance, especially if you’re very physically active, is the key to getting your nutritional needs met.
      Yes, Soda is not good when you’re on Keto.
      Soda contains lots of sugar and carbs that are unhealthy and unhelpful in the process.

  15. I enjoyed reading the comments on doing the Keto diet. I am going to keep on it even if I don’t lose weight. I feel it is helping me internally.

  16. How many calories do you guys usually eat on keto? i know it isn’t a calorie diet but i like to keep my calories counts. (Woman) i know men have a higher calorie intake. I also run/Hiit cardio 30-40 mins 4-6 days a week (which burns 400-500 calories per session)
    Thank you!

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