It has been said that the keto diet lacks fiber. Nothing could be further from the truth. There are plenty of keto fiber sources that can be included in your diet, plus they help you stay full, support your weight loss efforts, and support gut health.
This guide explains why you need fiber on keto (unless you’re choosing to follow a keto carnivore approach, which has minimal to no fiber), how much you need in a day, and fiber-rich foods that won’t kick you out of ketosis.
Dietary fiber is a non-digestible carbohydrate that’s found in plant foods. Although fiber is popularly known to provide bulk to the stool, which promotes bowel movements, it has other functions that support good health on the keto diet (*). These include better satiety, blood sugar regulation, improvement of IBS symptoms, and reduced LDL cholesterol.
Here’s more about each role of fiber as backed by research:
- Satiety: Getting fiber on keto helps by slowing down the absorption of fat, which then increases feelings of fullness and reduces food intake (*). This is important for those who are on the keto diet to lose weight.
- Blood sugar control: High blood sugar is damaging to your health. For people with diabetes or are at risk of developing it, the keto diet is an effective way to lower blood sugar. Fiber, in particular, isn’t digested and absorbed by the body, making it helpful for keeping your blood sugar within range (*).
- IBS symptom relief: A systematic review on fiber and IBS found that soluble fiber is effective in reducing overall IBS symptoms, which may be possible through an increase in short-chain fatty acids (SCFAs). SCFAs have anti-inflammatory properties (*).
- Reduced LDL cholesterol: High levels of low-density lipoprotein — small dense (sd) LDLs in particular — increase your risk of heart disease (*). Fiber may work to reduce cholesterol by altering the metabolites of gut bacteria, which can change the way your body processes cholesterol (* , *).
Two types of fiber exist:
Soluble fiber easily dissolves in water and forms a viscous, gel-like substance. When soluble fiber reaches the large intestine, it gets broken down into short-chain fatty acids (SCFAs), such as butyrate, propionate, and acetate (*). According to research, SCFAs improve gut health by maintaining the integrity of the intestinal barrier and providing protection from inflammation (*).
Keto-friendly sources of soluble fiber include broccoli, cabbage, brussels sprouts, avocados, flax seeds, sunflower seeds, and hazelnuts.
Insoluble fiber, on the other hand, does not dissolve in water. It’s beneficial for those who are experiencing constipation since it increases luminal bulk. On the list of fiber functions above, we mentioned that fiber can help with IBS symptoms. It’s important to note that soluble fiber improves IBS symptoms, whereas insoluble fiber may worsen IBS symptoms (*).
Examples of keto-friendly insoluble fiber sources include green beans, okra, spinach, cocoa, and coconut flour.
“The FDA recommends 25 grams of fiber daily, which you can get from high-fiber foods like chia seeds, avocados, pecans, broccoli, and almonds,” said Bill Bradley, a registered dietitian and owner of Mediterranean Living.
The USDA, on the other hand, gets more specific by recommending a daily fiber intake of 25 grams per day for women and 38 grams per day for men (*).
Whether you should aim to consume this amount of fiber or not depends on your goals and tolerance. For example, some people find that consuming too many high-fiber keto foods leads to excessive bloating and gas. Other symptoms may include nausea, stomach cramps, and constipation. Aside from these symptoms, eating large amounts of plant foods may interfere with nutrient absorption due to their compounds called antinutrients (*).
If you choose to include more fiber in your keto diet, pay attention to how you feel then adjust accordingly. It’s worth noting that some individuals coming from a high-carb diet experience constipation. “You may have noticed after beginning the keto diet that your digestion has slowed down,” said Dr. Sean Ormond, who is dual board-certified in Anesthesiology and Interventional Pain Management, and owns Atlas Pain Specialists.
This is where adding keto foods high in fiber becomes beneficial.
A low-carb diet doesn’t have to be a low-fiber diet. You can see in the examples below that you have lots of options to boost your fiber intake without going over your carbohydrate limit of 50 grams per day. Include these foods into your weekly meal plan or enjoy them as snacks:
Fruits (100 gram serving)
- Avocados: Fiber 7g | Net Carbs 2g (*)
- Coconut meat: Fiber 9g | Net Carbs 6g (*)
- Raspberries: Fiber 7g | Net Carbs 5g (*)
- Strawberries: Fiber 2g | Net Carbs 6g (*)
- Blueberries: Fiber 2g | Net Carbs 13g (*)
Nuts and Seeds (100 gram serving)
- Flax seeds: Fiber 27g | Net Carbs 2g (*)
- Sunflower seeds: Fiber 9g | Net Carbs 11g (*)
- Hazelnuts: Fiber 10g | Net Carbs 7g (*)
- Almonds: Fiber 13g | Net Carbs 9g (*)
- Chia seeds: Fiber 34g | Net Carbs 8g (*)
- Pumpkin seeds: Fiber 6g | Net Carbs 9g (*)
- Pecan nuts: Fiber 10g | Net Carbs 4g (*)
Vegetables (100 gram serving)
- Broccoli: Fiber 2g | Net Carbs 4g (*)
- Cauliflower: Fiber 2g | Net Carbs 3g (*)
- Cabbage: Fiber 3g | Net Carbs 3g (*)
- Brussels sprouts: Fiber 4g | Net Carbs 5g (*)
- Green beans: Fiber 3g | Net Carbs 3g (*)
- Okra: Fiber 2g | Net Carbs 3g (*)
- Spinach: Fiber 2g | Net Carbs 0g (*)
- Edamame: Fiber 5g | Net Carbs 4g (*)
- Artichokes: Fiber 5g | Net Carbs 6g (*)
- Collard greens: Fiber 4g | Net Carbs 1g (*)
- Bell peppers: Fiber 1g | Net Carbs 4g (*)
Other Sources of Fiber on Keto
- Psyllium husk (100 grams): Fiber 78g | Net Carbs 11g (*)
- Acacia fiber (1 tablespoon): Fiber 5g | Net Carbs 0g (*)
Discover common questions and answers pertaining to fiber on the keto diet:
Does fiber kick you out of ketosis?
No. Your body cannot digest fiber and therefore it will not cause your blood glucose levels to rise unlike other carbohydrates. As long as you limit yourself to 50 grams of net carbs daily, you should be able to stay in ketosis.
Is high fiber good on keto?
Yes and no. Getting adequate amounts of fiber is good for your health, but some people tend to experience digestive issues like bloating and constipation when consuming more fiber. If you’re in doubt, test various amounts of fiber and watch how you feel.
Does fiber really cancel carbs?
No. Fiber doesn’t cancel out carbs, although it’s not digested like other carbs. It’s not a source of energy and doesn’t raise your blood sugar, and it helps with weight loss, digestive health, cholesterol, and more.
Studies support the benefits of dietary fiber, such as better satiety for weight loss, balanced blood sugar levels, relief from IBS symptoms (which applies to soluble fiber), and reduced LDL cholesterol.
Based on the recommended fiber intake, you should aim for at least 25 grams per day. However, because some people tend to get digestive issues with higher amounts, it’s a good idea to start with a smaller amount and adjust over time based on your tolerance.
But, at the start of your keto diet journey, remember to incorporate fiber to relieve constipation, which is one of the common symptoms experienced by beginners.
Fortunately, you won’t run out of low-carb high-fiber fruits, vegetables, nuts and seeds, and supplements!