Eating enough grams of fiber each day is important, and you can find that out very quickly if you don’t meet your daily fiber intake needs and have to suffer the digestive consequences of constipation. However, if you’re on a ketogenic diet, you’re cutting down your carbohydrate intake to as little as 5% of your calories per day, so how do you get enough fiber? We have tips for how to get more fiber—keto-friendly fiber that won’t interrupt your metabolism.
What Is the Keto Diet?
The ketogenic diet was developed originally to treat children with epilepsy. The diet switches the body’s metabolic processing from running on sugar (blood glucose) to running on fat (ketone bodies). It gets its name from this natural process, called ketosis.
Our bodies are designed for ketosis. The body only prefers to run on sugar because humans have evolved to store fat during times of famine. We’re not in so much danger of starvation in the developed world, so these days it’s much healthier to reduce sugar and carb consumption and lose dangerous body fat.
By training the body to burn fat for energy, it’s possible to achieve rapid and safe weight loss, including hard-to-reach visceral fat nestled around your organs. By cutting out glucose, you protect your blood sugar levels and reduce your risk of developing type 2 diabetes. By relying on ketones for energy, you can increase your mental acuity because ketones are molecules that can cross the blood-brain barrier unaided.
Sounds great, right? But is there any downside to the keto diet?
Well, the keto diet, as well as other high-fat, moderate-protein, low-carb diets, comes with an adjustment period. When you first start the diet, you may experience flu-like symptoms such as fatigue, brain fog, and general discomfort. But give it a week and those aggravations should subside.
Finding high-fiber foods that support your digestive system without adding to your net carbs can be a struggle too, which is why we’ve included a list of the best keto fiber foods below.
The Importance of Dietary Fiber
There are two types of dietary fiber: soluble and insoluble fiber.
- Soluble fiber is able to dissolve in water and is found in foods like whole grains, apples, beans, and barley.
- Insoluble fiber is in foods considered “roughage.” Basically the parts of plant foods we cannot digest but that greatly benefit our digestive functioning. This type of fiber is in wheat, nuts, beans, and starchy vegetables like potatoes.
Getting a proper amount of fiber from your diet is necessary on several fronts.
This type of dietary fiber is a carb we cannot digest but our beneficial gut bacteria can. By feeding your good gut bacteria, you keep opportunistic bacteria from robbing you of wellness and help fight against invading viruses that find their way into the body.
Quick note: prebiotic foods are different than probiotics. Probiotics are foods like Greek yogurt, kimchi, and kefir, which introduce brand new good bacteria to the gut. Prebiotic fiber is food for the home team.
2. Bulk Fiber
This is the type of fiber that dissolves in water and becomes gel-like when in contact with moisture (exactly like chia seeds in chia seed pudding). Soluble bulk fiber helps your digestion by adding comfortable bulk to your stool, making sure there’s enough moisture to help it move along your digestive tract, and enough bulk for your intestinal walls to grab onto. This helps prevent constipation before it starts, encourages regular bowel movements, and aids in reliable gut health.
3. Fiber and Satiety
More fiber in your diet helps slow stomach emptying and digestion, which provides you with two important benefits. First, you feel fuller longer (and are therefore less likely to overindulge on calories), And second, any sugars in your food hit your bloodstream slower (protecting your blood sugar levels from dangerous spikes).
A good amount of fiber intake can contribute to digestive and heart health by lowering “bad” LDL cholesterol, collecting it for removal with your waste before it can build up in your arteries.
But where does that leave you on keto? So many high-fiber foods are also high in carbs, and while you may not miss the occasional bloating that accompanies beans, you don’t want to lose out on the benefits of fiber either.
Is There Such a Thing as Too Much Fiber?
Fiber is a necessary part of the human diet. Eating too much fiber is rare and often involves over-supplementing fiber without enough water for it to absorb as it moves through your digestive system. In that instance, less fiber or more water can help regulate the issue.
A fiber-restricted or low-fiber diet is sometimes prescribed for those with inflammatory bowel conditions like IBS or Crohn’s disease, not because fiber is bad, but because inflamed bowels need a short period of rest to heal. Otherwise fiber should be a normal part of your daily food intake.
Get More Fiber: Keto-Friendly High-Fiber Foods
Without further ado, here are the top 10 non-starchy low-carb sources of fiber you can eat on keto.
Leafy greens like Brussels sprouts, collard greens, spinach, and broccoli greens often have more vitamin C than oranges and whopping levels of vitamin K, potassium, and folate. Each of these little cabbages is about 1.7 grams of carbs each, and 0.7 is pure fiber content. Your net carb per sprout goes down to 1, and not only is that a high-nutrient benefit for the cost of 1 carb, but you can easily steam them for a delicious side dish.
Of course avocados are already on your shopping list as a healthy fat on keto, but did you know they are a fiber source as well? Despite being green, avocados are not vegetables but single-seed berries. Avocados come with buttery-rich textures and a long list of nutrients, including vitamins B5, B6, C, K, folate, and more potassium than a banana. A single medium-sized avocado (about 200 grams) has nearly 30 grams of fat, 4 grams of protein, and 3.8 grams of net carbs in exchange for over 13 grams of fiber.
Most people in the modern world aren’t eating enough seeds, but luckily that’s very easy to remedy by tossing flaxseeds into salads and trail mixes, or ground flaxseeds into smoothies or keto breads. Flaxseeds are extremely low in net carbs (0.1 gram per tablespoon), and much higher in heart-healthy fiber (1.9 grams per tablespoon).
Flaxseeds have been shown to increase satiety and improve cholesterol and blood pressure levels.
Pro tip: they’re easier to absorb if you get them pre-ground instead of consuming them whole.
4. Chia Seeds
Speaking of seeds, chia seeds are those swell (get it, because they swell up!) little seeds that are a good source of protein and fat and high in fiber. For every ounce of chia seeds you consume, you’re getting about 2 grams of net carbs and an impressive 10 grams of fiber. An excellent trade-off, especially considering that chia seeds also contain calcium for your bones.
You may come to know and love zucchini on keto, mostly because it makes for a perfectly healthy low-carb pasta replacement in the form of zoodles (zucchini noodles). It turns out that not only can they spare you in carbs, but they can also deliver plenty of fiber. Specifically, 1 cup of chopped zucchini offers up 1.4 grams of fiber and 1.5 grams of protein in exchange for 2.8 grams of carbs. With manganese, vitamin C, vitamin K, and carotenoids, you’re getting a lot more nutrition when zoodles replace pasta.
You won’t even think about starting a keto diet without hearing about coconut oil. The MCTs (medium-chain triglycerides) in coconut oil help to boost energy levels by providing you with exogenous (external) ketones. This is why people drop coconut oil into their keto coffee in the morning, especially if they’re utilizing intermittent fasting techniques.
But coconuts provide more than just their cold-pressed oils. You can use coconut flour to make keto replacement desserts, coconut milk for smoothies and various recipes, and raw coconut can be eaten for the fiber it provides.
Specifically, half a cup of raw coconut (shredded) has about 2.5 grams of net carbs and 3.6 grams of fiber. That brings the total carbs to only 6.1 grams. You also get over 13 grams of fat, 1.4 grams of protein, selenium, potassium, copper, manganese, and an assortment of omega-3 fatty acids.
The coconut is like the gift that keeps on giving for a healthy diet on keto.
Full of antioxidants, vitamin C, and potential anti-cancer substances like ellagic acid, gallic acid, and quercetin, red raspberries have anti-inflammatory properties and 8 grams of fiber for only 6.7 grams of net carbs per cup.
Blackberries are similarly high in antioxidants and vitamin C. For 1 cup of blackberries you gain 8 grams of fiber for a net carb content of 6 grams. A nice mixed-berry treat could net you a substantial amount of healthy fiber.
Cauliflower, like zucchini, is a valuable staple food in the keto dieter’s kitchen because it can be used as an alternative to pizza crust, mashed potatoes, and rice. With a neutral flavor and versatile texture, cauliflower would be useful on keto even if it had no nutrients, but, of course, it still does, and one of those benefits is fiber content.
One cup of raw cauliflower gives you 2 grams of fiber for 2.8 grams of net carbs. It also has 2 grams of protein and micronutrients like choline, folate, and vitamins B6, C, and K.
Whatever the variety of edible mushroom you choose, be it beech, button, porcini, chanterelle, maitake, or lion’s mane, you’ve got yourself a nutritional powerhouse of a food. Full of vitamin C, potassium, and B vitamins galore (B1, B2, B3, B5, and B9), mushrooms aid in lowering cholesterol levels (which can help protect against heart disease according to the American Heart Association), improve your immune system’s responses, and help with blood sugar control.
A 100-gram portion of white mushrooms, for example, has 2.3 grams of net carbs, 3.1 grams of protein, and 1 full gram of fiber. Fiber ratios vary from mushroom to mushroom, so shop around to find the one that best suits your taste, budget, and dietary needs.
Full of biotin, vitamin K, and various antioxidants, tomatoes are good for your blood pressure and may have anti-cancer protective properties along with carotenoids, which are best absorbed when combined with a healthy fat like olive oil. A perfect addition to a healthy salad, 1 cup of cherry tomatoes has 1.8 grams of fiber, 1.3 grams of protein, and 0.3 grams of fat for the 4 grams of net carbs you consume.
Fiber Supplements for Keto
If you’re dealing with digestive slowdown while in ketosis and nothing you eat is helping, there are natural supplements you can try. We suggest that you always start slow with a new supplement. You may only need a fiber supplement temporarily if you’re new to keto and in your adjustment period, so be sure to listen to your own body as you find out what “enough fiber” means for you.
Natural, keto-friendly fiber supplements include ground flaxseed (#3 on the list), psyllium husk powder or chicory root fiber, which is found in many over-the counter dietary supplements due to its ability to increase feelings of fullness.
The Force of Fiber
There are low-carb vegetables, fruits, and seeds that you can safely eat on keto that will provide you with the fiber you need to stay regular. It isn’t glamorous to talk about, but having comfortable and relatively frequent bowel movements can easily be the difference between a good day (or week or month) and a bad one. If you find that you’re not getting enough fiber on keto from whole foods like the ones listed above, there are natural supplements that may help you even out as you adjust to a perpetual state of ketosis.