The ketogenic diet, often called the keto diet, is a popular eating plan that focuses on high-fat, low-carbohydrate foods. It's used to reach ketosis, where the body burns fat for fuel instead of sugar (glucose). While the keto diet can be effective for weight loss and managing certain health conditions, it's often criticized for its lack of fiber. This article explores the importance of fiber on a ketogenic diet and provides practical tips for incorporating enough of this essential nutrient.
What is the Ketogenic Diet?
The ketogenic diet includes eating high-fat, low-carbohydrate foods to reach ketosis. In ketosis, the body uses fat for fuel, instead of sugar (glucose). There are several different styles of keto diets. This is the original and best-studied of the different diet strategies. All foods must be weighed on a scale to achieve a relative weight distribution of 4 grams of fat for every 1 gram of combined protein and carb eaten throughout the day. In other words, you will likely need to avoid all carb-rich foods (like pasta, potatoes, fruit, etc.).
Types of Keto Diets
There are various types of ketogenic diets, including:
- Standard Ketogenic Diet (SKD): A very low carb, moderate protein, and high fat diet, typically containing 70% fat, 20% protein, and 10% carbs.
- Cyclical Ketogenic Diet (CKD): Involves periods of higher carb refeeds, such as 5 ketogenic days followed by 2 high carb days.
- Targeted Ketogenic Diet (TKD): Allows you to add carbs around workouts.
- High Protein Ketogenic Diet: Similar to the SKD, but includes more protein, with a ratio of often 60% fat, 35% protein, and 5% carbs.
The standard and high protein ketogenic diets have been studied extensively. Cyclical or targeted ketogenic diets are more advanced methods and primarily used by bodybuilders or athletes.
The Importance of Fiber
Fiber plays a vital role in digestive health. Because it’s not digested by your body, it passes through your system and keeps you regular by softening and adding bulk to your stools, per Mayo Clinic. And it has benefits beyond bowel movements: It feeds the good bacteria in your GI tract, aiding healthy digestion and nutrient absorption.
Read also: High-Fiber Diet for Better Health
Digestive Health
Fiber is essential for digestive health as it is not digested by the body and passes through the system, softening stools and adding bulk, which promotes regularity. Fiber also nourishes beneficial gut bacteria, supporting healthy digestion and nutrient absorption. “The digestive tract is where your body’s second brain is, and it’s home to the majority of your immune system,” says Elia. “If you’re following keto, it should be one of your biggest priorities to make sure you get adequate fiber to keep your gut healthy and happy,” she adds. And, she notes, high-fat diets slow digestion and decrease GI motility, so it’s especially important to get enough.
Recommended Daily Intake
The USDA’s 2020-2025 Dietary Guidelines for Americans set a goal of 28 to 34 g of fiber a day, depending on age and sex.
The Challenge of Getting Enough Fiber on Keto
One thing that’s often missing from the keto diet? A little bit of roughage. The popular diet, which typically requires you to get up to 80 percent of your calories from fat and only 20 to 50 grams (g) of carbohydrates per day, is often criticized for its lack of fiber. And that’s certainly true in the case of some of its followers. “A poorly planned keto diet is at risk of being deficient in fiber,” says Dana Elia, RDN, an integrative and functional medicine dietitian in Lancaster, Pennsylvania. Department of Agriculture (USDA): More than 90 percent of women and 97 percent of men don’t meet their recommended daily amount of fiber. Rule out most sources of carbohydrates, including whole grains, fruits, and legumes, and it’s even more likely you’ll be fiber deficient.
Why Fiber is Often Lacking
The ketogenic diet reduces your total carb intake to less than 50 grams a day. The keto diet excludes carb-rich foods like grains, beans, fruits and starchy vegetables. The drastic reduction in carbohydrate intake leads the body to switch its fuel source from glucose(sugar) to fatty acids. Many fiber-rich foods can also be carb-heavy.
Potential Consequences of Low Fiber Intake
Constipation is likely the greatest long-term complication of the keto diet because of a low fiber intake. Fiber is a form of carb that is digested not by our human cells, but by the microbes in our gut. Any high-fiber foods (like beans, whole grains, and certain fruits) are also high in carbs, which is not typically part of the keto diet. Low fiber intake can disrupt gut microbiota and lead to chronic constipation, while inadequate magnesium, vitamin C and potassium can contribute to muscle cramps, fatigue and weakened immune function,” explains Dr.
Read also: Guide to Keto Fiber
How to Increase Fiber Intake on Keto
Following a keto diet food list doesn’t mean it’s impossible to get what you need, but you have to remain diligent and determined to make it happen, says Keri Glassman, RDN, who is in private practice in New York City. Many fiber-rich foods contain few net carbs - that is, total carbs minus fiber and sugar alcohols, per Atkins.com - and will keep you in ketosis, which is the metabolic state that causes your body to burn fat instead of carbs.
Fiber-Rich, Keto-Friendly Foods
Here are some keto-friendly foods that are high in fiber:
- Avocados: Half an avocado contains just 1.4 net carbs, but a whopping 5 g of fiber, per the USDA. “All keto followers should consume avocados, because they’re a great source of fiber and fat,” says Elia.
- Chia Seeds: One ounce (oz) of chia seeds offers 9.6 g of fiber (and a net carbs total of 2.2 g), per the USDA. You can make chia seed pudding by mixing the seeds with liquid, creating a gel-like substance that you can enjoy mixed with fruits, natural sweeteners like honey, and your choice of spices. Glassman suggests sprinkling chia into small, low-carb smoothies or onto oatmeal, eggs, or a salad.
- Flax Seeds: The USDA reports that 1 tablespoon (tbsp) of ground flax boasts 2 g fiber and 0 net carbs. Basically, a freebie - eat up. So you can better absorb the nutrients in flax, make sure they’re ground - you'll reap the heart-healthy, cholesterol-lowering benefits of flaxseed’s high omega-3 fatty acid content, says Mayo Clinic. These small seeds make a killer crunchy coating for fish or chicken in lieu of breading, says Glassman.
- Nuts: Nuts can be a great option on the keto diet because of their fiber and fat, says Glassman.
- Pecans: are one of the lowest-carb nuts, offering just 1.2 net carb per oz (19 halves), notes the USDA. That amount will also supply 2.7 g of fiber.
- Almonds: are another good choice. One of the most fiber-rich nuts, they clock in at 3.5 g (and about 2.5 g of net carbs) per oz (23 whole kernels), notes the USDA
- Macadamia Nuts: 3/4 cup = 9 grams of fiber and 5 grams of net carbs.
- Low-Carb Vegetables:
- Collard Greens: One cup of cooked collards has about 2 g of net carbs and 5.6 g of fiber, per the USDA. Starchy veggies like sweet potatoes are notoriously off-limits on keto, but there are plenty of keto-friendly greens. Target high-fiber picks like collards, says Elia. They cook down nicely, so go for cooked rather than raw greens to get in more fiber per cup.
- Cauliflower: A 1 cup serving of this low-carb veggie has only about 3 g of net carbs and 2 g of fiber, notes the USDA. Plus, it’s super versatile: It can be used to make cauliflower pizza crust, chopped small to stand in for rice, mashed to replace mashed potatoes, and blended into creamy soups.
- Spinach: When cooked, 1/2 cup = 4 grams of fiber and 1 gram of net carbs.
- Broccoli: 1 cup of chopped, cooked broccoli = 5 grams of fiber and 6 grams of net carbs.
- Seeds:
- Pumpkin Seeds: An ounce of dried pumpkin seed kernels yields a little more than 1 g of net carbs and 1.7 g of fiber, per the USDA. Plus, they’re simple to grab as a handful for a snack, so you can sneak a bit more fiber into your day.
- Coconut: A small piece of coconut meat (about two inches by two inches) offers about 3 g of net carbs and 4 g of fiber, per the USDA. “Plus, it goes double duty to help you get more fat,” says Elia. Look for this in the frozen section at some grocery stores. If you can’t find it near you, go for unsweetened shredded coconut.
- Berries:
- Raspberries: A half cup of fresh raspberries offers 4 g of fiber and 3.3 g of net carbs, the USDA notes. It can be tough to figure out how to fit fruit into a keto diet, but raspberries are a particularly good choice because of their fiber content. Consider cooking down frozen raspberries and using them as a syrupy topping on keto pancakes.
- Artichokes: One canned artichoke heart offers 1.7 g of fiber and less than 1.9 g of net carbs. are a surprisingly good option for getting more fiber into your keto diet. Add them as a topping to a keto pizza, roast or grill fresh artichokes, or bake with keto-friendly cheese as an appetizer.
- Sauerkraut: A half cup of sauerkraut supplies 2 g of fiber and a little more than 1 g of net carbs, per the USDA. Fermented foods - packed with probiotics - are good for your gut, full of flavor, and low in carbohydrates. Plus, you can use it to add a tangy flavor boost to whatever you’re eating, from cuts of meat to salads.
- Psyllium Husk: 1 Tbsp = 8 grams of fiber and less than 1 gram of net carb. All of our Keto Katz breads are high in fiber because we use psyllium, check them out here.
Tips for Increasing Fiber Intake
- Increase fiber slowly: Increase your fiber slowly over a period of days or weeks. We don’t want to have too much at once and cause a bowel obstruction or anything!
- Drink more water: Drink more water because that’s what’s going to help “activate” the fiber and also prevent clogging the pipes.
- Vary your fiber sources: Vary the high fiber foods you consume (per the list in the handout) to be sure you’re getting a variety of nutrients and fiber types.
- Listen to your body: Listen to your body- it, will tell you what it likes and doesn’t like. Don’t force it to do what it doesn’t want to do.
Fiber Supplements
Adding a fiber supplement is a great way to add more fiber to your diet.
Potential Benefits of Fiber on Keto
Effect of low and high fibre diets on gut microbiota composition, diversity, and function in host physiology. There’s two types of fiber in plants: soluble and insoluble fibers. They are both beneficial, they exist in varying amounts in different foods, and we should try to eat a range of foods with fiber daily. When you eat them, they pass through the whole gastrointestinal tract without getting digested or absorbed, until they reach the colon. Each type of fiber is needed, and this is what they do:
- Soluble fiber: gets fermented by the bacteria in your gut, the bacteria then produce short chain fatty acids which gets absorbed by colon cells. This keeps your colon healthy!
- Insoluble fiber: this does not get fermented, it bulks up the poopies and makes it easier to eliminate
Colon Health
Colon health because it makes poop nicer to eliminate (preventing hemorrhoids) it promotes a healthy microbiome which positively affects your whole body and mental health.
Read also: Gut Health on Carnivore Diet
Natural Immunity
Improves natural immunity since most of your immune system is in the gut.
Decreased Allergies
It decreases allergies of all kinds by reducing leaky gut.
Blood Sugar and Cholesterol
Lowers blood sugar and Reduces LDL cholesterol.
Weight Loss
Helps you feel fuller which obviously contributes to weight loss.
Potential Downsides of Keto
The keto diet can, for instance, make it harder to get adequate amounts of essential nutrients.
Nutrient Deficiencies
“Because the keto diet is so restricted, you’re not receiving the nutrients - vitamins, minerals, fibers - that you get from fresh fruits, legumes, vegetables and whole grains,” says Dr.
Keto Flu
Also, when people start the keto diet, they go through the keto flu. Keto flu symptoms appear a few days after starting the diet. People report feeling foggy, irritable, nauseous and tired. This eventually goes away once your body adjusts to your eating changes.
Heart Health
The high-fat nature of the diet could also have negative impacts on heart health. The American Heart Association recommends limiting saturated fat intake to less than 6%. “In practice, many people eat high amounts of saturated fats, which could increase your risk of heart disease,” says Dr. Cheema. “You may be eating a lot of fatty meat thinking it’s a good thing for you because it's high in fat. This can dramatically alter your lipid profile. While high-fat diets can elevate LDL (“bad”) cholesterol, the type of saturated fat matters. The bottom line is that having more fats in your diet can lead to higher cholesterol.