When you start a low-carb ketogenic diet, you’re doing yourself a world of good on a lot of fronts: fewer sugars from carbs and sweets means fewer blood glucose spikes, and more stable blood glucose levels lead to lower risk factors for type 2 diabetes, obesity, and other metabolic disorders. But getting enough fiber on a keto diet takes some finesse. That’s because carbs are often high-fiber foods, and if you cut them down to just 5% of your diet, where will you find the dietary fiber you need for a healthy and functional digestive tract? Just as vegetarians and vegans must prioritize the best sources of plant protein, keto dieters must evaluate which foods provide the most fiber for the least amount of carbs. If your question is, “How to get more fiber on keto?” then we have the answers you’re looking for.
The Fundamentals of Fiber
No one can go without fiber for very long. In fact, the only time a doctor recommends a low-fiber or fiber-restricted diet is in cases of such severe bowel inflammation that it’s more important for the digestive tract to rest than it is to prioritize comfortable bowel movements. Even in these cases fiber restriction is temporary, just long enough to allow the intestinal tract to heal. After that, it’s back to including good sources of fiber in your daily diet.
Fiber is indigestible to humans, but far from being useless roughage, fiber nourishes our good gut bacteria and bulks up our waste just enough for comfortable passage through the body (neither too much fiber causing constipation, nor too little causing diarrhea). Fiber intake works both ways to provide you with comfortable digestion and a strong army of gut flora to help fight against harmful viruses and bacteria, mostly because there are two types of dietary fiber working together.
- Soluble fiber: Water-soluble fiber is the type that can dissolve in water, swelling up to become gel-like and viscous. When consumed, soluble fiber helps slow down your digestion (making you feel fuller for longer), lessens the impact of meals on your blood sugar levels, and draws moisture to your stools so they don’t become hard and you don’t become painfully constipated. Water-soluble fiber also feeds your gut bacteria as prebiotic fiber, which then leads to the creation of beneficial short-chain fatty acids for colon health.
- Insoluble fiber: This type of fiber doesn’t dissolve in water, and while it makes its way through your digestive system largely unchanged, it adds solid bulk to your stool, which lessens instances of diarrhea.
So, how to get enough fiber on keto? Let’s find out!
How to Get More Fiber on Keto: Top 10 Low-Carb, High-Fiber Foods
Which foods help you walk the line between carbs and fiber? Here’s our top 10 list of high-fiber, low-carb foods.
Low-carb veggies include cruciferous vegetables like cabbage, Brussels sprouts, broccoli, and cauliflower. While many high-fiber starchy vegetables are no-nos on keto, it’s important to remember that fiber content may not always translate to net carbs: carbs coming from a type of fiber you can’t digest don’t count as carbs absorbed by your body, meaning consuming them won’t impact your weight-loss efforts.
Not only do cruciferous veggies have anti-cancer components, but they also provide nutritious sources of fiber for relatively few net carbs. Half a cup of broccolini, for example, offers up 1.1 grams of fiber for 1.8 grams of total carbs and 0.7 net carbs, meaning it’s at a nearly perfect “break even” ratio. On the other hand the same amount of leafy greens in the form of collard greens has 3.6 grams of fiber for just 2 grams of net carbs.
2. Chia Seeds
If you’re looking for an example of water-soluble fiber, chia seeds illustrate it perfectly. When soaked in any liquid (say in a bowl of overnight oats) they swell up and give a smoothie-like consistency to the dish. Chia seeds provide healthy protein, a ton of unique micronutrients you can only get from seeds, and help increase feelings of satiety when you eat them because they keep swelling up as they move along.
An ability to help curb your appetite means that chia seeds also help you reduce your overall calorie consumption throughout the day, leading to further healthy weight loss. Just 1 ounce of chia seeds brings you over 10 grams of fiber for a mere 1.7 grams of net carbs.
3. Raw Coconut Flesh
Those on keto may already be well aware of the value of coconut oil, coconut flour, and coconut milk as substitutes for high-carb foods. They also provide exogenous (from the outside) ketogenic sources of energy and noteworthy fiber content. A cup of shredded raw coconut delivers 7 grams of fiber for 5 grams of net carbs.
Would a keto diet even be possible without avocados? One of the best healthy fats around and versatile enough to blend into smoothies, make into ice cream, and enjoy as a spread or dip, avocados also provide a significant amount of fiber. Specifically, a single avocado at about 200 grams in weight could give you over 13 grams of fiber for just 3.6 grams of net carbs. The health benefits of avocados seem to know no bounds.
High in vitamin C, B vitamins, and potassium, mushrooms grow in the dark. Once exposed to sunlight they soak up vitamin D much the same way our own skin does. Besides their valuable nutrient content, mushrooms can also provide some fiber. A cup of oyster mushrooms contains 2 grams of fiber for 3.6 grams of net carbs—a bit of a deficit, but mushrooms are still overall a low-carb food with unique nutritional contributions.
Nuts like pecans and almonds are full of healthy fats that contribute perfectly to keto diets. They also come with vitamins and minerals like copper, manganese, and vitamin E. Each nut contains a little helping of fiber; for example, a ratio of 2.7:1.2 fiber to net carbs for pecans, and 3.3:2.1 for almonds. A heart-healthy diet would not be complete without high-quality nuts and seeds.
7. Ground Flaxseeds
Speaking of seeds, another nutritional powerhouse is flaxseed. One of the best when it comes to omega-3 fatty acids, flaxseeds are mineral-rich foods full of selenium, manganese, copper, phosphorus, magnesium, and thiamin, and they come with so much fiber they’re often used in dietary fiber supplements. Including ground flaxseeds in your meal plans can be incredibly easy, whether blended into smoothies, sprinkled into salads, or baked into keto-friendly recipes. An ounce of ground flaxseeds grants you 7.6 grams of dietary fiber for just 0.5 grams of net carbs.
Zucchinis are great assets to keto because, when spiralized, they can easily replace wheat-based pasta. Zucchini noodles (zoodles) can also be used to make gluten-free veggie casseroles and lasagnas, and they’re full of nutrients like vitamin C, vitamin K, manganese, and carotenoids (also found in carrots). A chopped cup of zucchini offers up 1.4 grams of fiber for 2.8 grams of net carbs, and while it’s got a few more grams of carbs than fiber, it’s also got way fewer carbs than spaghetti.
9. Bell Peppers
Whatever color of bell pepper you choose—orange, red, yellow, green, or purple—each is full of vitamin C and vitamin E, plus 3.1 grams of fiber for about 6 grams of net carbs. Again, when it comes to a low-carb diet, the goal isn’t to eat no carbs; it’s to choose your carbs wisely so that you get significant nutritional bang for your carb buck.
10. Pumpkin Seeds
Whole pumpkin seeds, aka pepitas, can be baked at home and seasoned to your personal taste preference, either with cinnamon and sweet or turmeric and spice. An ounce of pumpkin seeds yields 3 grams of fiber for just 1 gram of net carbs, a perfect 3-to-1 win.
Do You Need Fiber Supplements?
The daily amount of fiber recommended by the USDA is 25 grams for women and 31 grams for men. These guidelines assume you’re eating a moderate-fiber diet full of plenty of whole grains and legumes however, which isn’t necessarily true for those on keto. Keto dieters may need a little bit more.
If despite your best efforts to eat enough fiber you nevertheless don’t feel right, you may want to ask your doctor to recommend a natural fiber supplement. Over-the-counter fiber medications may be too aggressive, with side effects like cramping, bloating, or gas, but psyllium husk fiber is a popular natural fiber supplement, with its own unique health benefits and an ability to be used in gluten-free recipes and baking as a thickening agent. While you may prefer to use ground flaxseeds because they have more omega-3 fatty acid content (psyllium fiber has no fat content), you also may want your fiber supplement to double as a baking ingredient, so the choice is up to you.
Fiber sources will always need to be part of your diet, no matter what diet you choose or need to follow for your health. While on the low-carb, high-fat keto diet, fiber may be a little bit harder to come by, but rest assured that there are keto-friendly foods that can provide most if not all of the fiber you need. Should you need more fiber because your bowel movements are off or your gut health feels compromised, look into natural dietary fiber supplements, and you may well find a simple solution to your problem that allows you to stay comfortably in ketosis.