Are fennel bulbs fattening?

Quick Answer

Fennel bulbs are not inherently fattening and can be part of a healthy, low-calorie diet. However, the way they are prepared can dramatically impact their calorie and fat content. Enjoying fennel bulbs raw, roasted, or sautéed with minimal added fat is the healthiest approach.

What Are Fennel Bulbs?

Fennel bulbs are the base of the fennel plant, which has a bulbous shape similar to onions or garlic. The bulbs have a crisp texture and licorice-like flavor.

Botanically speaking, fennel bulbs are vegetables. However, they have some unique nutritional properties that set them apart from other veggies:

  • Low in calories – One raw fennel bulb (87 grams) contains only 27 calories.
  • High in fiber – 3.5 grams per bulb, providing 14% of the daily value.
  • Rich in vitamin C – One bulb provides 17% of the RDI for this essential vitamin.
  • Contains antioxidants – Fennel bulbs provide antioxidants like kaempferol, quercetin, and rutin.
  • May reduce inflammation – Compounds in fennel have been shown to reduce inflammation in animal studies.

This impressive nutrient profile makes fennel bulbs a healthy addition to a balanced diet.

Are Fennel Bulbs Fattening on Their Own?

On their own, fennel bulbs are very low in calories and fat. One raw fennel bulb contains:

  • 27 calories
  • 0.2 grams of fat

With virtually no fat and minimal calories, fennel bulbs are not inherently fattening foods. Their high fiber content also helps promote fullness and curb overeating.

Studies confirm that increasing your intake of low-calorie, fiber-rich vegetables like fennel is an effective strategy for weight loss:

  • A study in over 133,000 people associated higher intakes of fiber-rich plant foods with lower body weight.
  • Eating more high-fiber, low-calorie vegetables promoted weight loss in a 6-month trial in obese adults.

So if you’re watching your calorie intake, fennel bulbs can be a nutritious, slimming addition to meals and snacks.

How Does Cooking Impact Fennel Bulbs’ Calorie Content?

While raw fennel bulbs are low in calories, the way you prepare them can alter their nutrition profile.

Here’s how different cooking methods affect the calorie content:


Enjoying fennel bulbs raw requires no added calories or fat. One raw bulb contains 27 calories.


Roasting fennel bulbs only requires a small amount of oil. Based on a 2 teaspoon (10 ml) serving per 3 bulbs:

  • Calories: 73
  • Fat: 6 grams


Sautéing fennel bulbs in 1 tablespoon (15 ml) of oil:

  • Calories: 114
  • Fat: 10 grams


Boiling fennel bulbs requires no added fat or calories. The calorie content remains around 27 per bulb.

Cream-based recipes

Preparing fennel bulbs in fat-rich sauces or baking them into cream-based casseroles significantly increases the calorie density. For example, 1 cup of alfredo pasta sauce can have around 330–900 calories.

Tips for Enjoying Fennel Bulbs Without Added Calories

Here are some tips to keep fennel bulbs slimming:

  • Enjoy them raw in salads or as snacks.
  • Roast them with just a drizzle of oil.
  • Sauté in broth instead of oil.
  • Combine with lean proteins like fish or chicken breast.
  • Avoid heavy creams and cheese-based sauces.
  • Opt for low-fat cooking methods like boiling.

With minimal added fat from oils or creamy ingredients, fennel bulbs can be a nutritious, low-calorie addition to a healthy diet.

Are Certain Parts of Fennel Lower in Calories?

The white bulbous base of the fennel plant is the lowest in calories. Other parts of the fennel plant have slightly varying nutrition:

Fennel stalks

The long green hollow stalks attached to the bulbs are also edible.

One cup (87 grams) of raw sliced stalks contains:

  • 30 calories
  • 3 grams fiber

So fennel stalks are very low in calories and provide an extra boost of fiber.

Fennel fronds

The delicate feathery green leaves attached to the stalks are called fronds. They have a mild anise flavor.

One cup (20 grams) of fresh fronds contains:

  • 5 calories
  • 1 gram fiber

The fronds are also very low in calories. They add nice flavor when used as a herb.

Fennel seeds

The tiny seeds contained within the bulbs have a more potent licorice flavor.

One tablespoon (6 grams) of fennel seeds contains:

  • 20 calories
  • 1 gram fiber

Fennel seeds pack more calories per gram. However, they are very flavorful so you likely won’t use large amounts.

Health Benefits of Fennel Bulbs

In addition to their low calorie content, fennel bulbs provide some powerful health benefits:

  • Rich in antioxidants. Fennel bulbs contain antioxidants like quercetin and kaempferol. These compounds help neutralize harmful free radicals and protect against chronic disease.
  • May reduce inflammation. The antioxidants in fennel demonstrate anti-inflammatory effects in test-tube and animal studies. More research is needed to confirm benefits in humans.
  • Excellent source of vitamin C. One bulb provides 17% of the RDI for immune-boosting vitamin C.
  • Promotes digestive health. Fennel bulbs are a good source of fiber. Fiber keeps your digestive system regular and helps maintain healthy gut bacteria.
  • May lower blood pressure. Some of the plant compounds in fennel, like anethole, inhibit an enzyme involved in constricting blood vessels.

Are Fennel Bulbs Suitable for Low-Carb and Keto Diets?

With only 5 grams of net carbs per bulb, fennel can definitely fit into low-carb eating plans like the keto diet.

Here’s a breakdown of the carb content:

  • Total carbs: 7 grams
  • Fiber: 2 grams
  • Net carbs: 5 grams

Plus, fennel bulbs have a very low impact on blood sugar levels, with a glycemic index of 15.

Some ways to enjoy fennel bulbs on keto include:

  • Thinly slice them into salads
  • Roast them with olive oil, salt, and pepper
  • Add to stir fries and sautes
  • Mix into omelets or frittatas

Just watch added high-carb ingredients like sugary sauces or creamy dressings. Within reason, fennel bulbs can be a nutritious low-carb vegetable.

Should You Eat Fennel Bulbs at Night?

Fennel bulbs are unlikely to disturb your sleep. In fact, some traditional medicinal practices recommend fennel tea before bed to aid digestion.

That said, everyone can react differently. Some anecdotal reports note that eating fennel close to bedtime led to looser stools or mild gastrointestinal discomfort.

If you have no digestive issues, the fiber, nutrients, and low calories in fennel bulbs make them a healthy option any time of day. But listen to your body. If they disrupt your sleep, stick to eating them earlier in the day.

Alternatives to Fennel Bulbs

If you don’t enjoy the strong licorice-like flavor of fennel bulbs, many other vegetables make good alternatives:


Onions have a similar bulb shape and crisp texture when eaten raw. They add great flavor for minimal calories:

  • 1 medium onion (110 grams): 46 calories, 2 grams fiber


Celery stalks have very few calories and provide crunch:

  • 1 cup (101 grams) chopped celery: 16 calories, 1.6 grams fiber


Cucumbers are low in calories and carbs. Enjoy them raw with dips or in salads:

  • 1 cup (104 grams) sliced cucumbers: 16 calories, 0.7 grams fiber

Bell peppers

Raw bell peppers make a delicious and nutritious snack:

  • 1 medium bell pepper (119 grams): 37 calories, 2.5 grams fiber


This Mexican root vegetable has an apple/potato taste. Add it raw to give meals a crunchy boost:

  • 1 cup (120 grams) jicama sticks: 46 calories, 6 grams fiber

Should You Refrigerate Fennel Bulbs?

Proper storage can help extend the shelf life of fresh fennel bulbs. The best way is to store them in the fridge.

Cold refrigerator temperatures between 32–40°F (0–4°C) slow down moisture loss and deterioration.

Some tips for refrigerating fennel bulbs:

  • Cut off stalks right after purchase. They draw moisture from the bulbs.
  • Place bulbs in a perforated plastic bag in the crisper drawer.
  • Minimize excess moisture by lining with paper towels.
  • Use within 5–7 days for best quality.

room temperature can hasten moisture loss and cause the bulbs to become limp. Refrigeration preserves freshness and prevents spoilage.

Can You Freeze Fennel Bulbs?

Freezing is another storage method to try preserving fresh fennel bulbs for later use.

To freeze:

  1. Clean and trim bulbs, removing stalks and blemished outer layers.
  2. Chop bulbs into 1⁄2 inch pieces.
  3. Blanch for 3 minutes in boiling water.
  4. Transfer to an ice bath to stop the cooking process.
  5. Pat pieces dry and arrange in a single layer on a baking sheet.
  6. Freeze until solid, then store in an airtight freezer bag or container.

Frozen fennel bulbs will keep for about 8–12 months. They work especially well incorporated into cooked dishes like soups, stews, and roasts after thawing.

Freezing helps retain most of their texture and flavor. However, they will become somewhat softer once thawed.

Common Questions About Fennel Bulbs

Here are some common questions about fennel bulbs:

Are fennel bulbs gluten-free?

Yes, fennel bulbs are naturally gluten-free. They are not grains and don’t contain the gluten proteins found in wheat, barley, and rye. This makes them safe for people with celiac disease or gluten intolerance.

Can you eat fennel bulbs raw?

Absolutely. Raw fennel bulbs have a delicious crunchy texture and refreshing licorice-like flavor. Thinly slice them and add to salads, slaws, and crudités platters for a nutritious crunch. Their natural oils become sweeter when exposed to air.

What does fennel taste like?

Fennel bulbs have a mildly sweet flavor with notes of black licorice, anise, and citrus. The fronds and seeds have a more intense anise-like taste. When cooked, fennel has a sweeter, mellower flavor.

What nutrients are in fennel?

Fennel bulbs are low in calories but rich in vitamin C, fiber, potassium, and antioxidants like quercetin. The seeds contain nutrients like calcium, iron, magnesium, and manganese as well.


Fennel bulbs are not fattening on their own. With only 27 calories per bulb, they are naturally low in calories and fat. Their high fiber content provides satiety on few calories.

However, the way fennel bulbs are prepared and added fats can increase their calorie content. Enjoy them raw, roasted, boiled, or sautéed with minimal added fat to keep them slimming. Skip cream-based sauces and cheese coatings if watching your weight.

With their refreshing crunch, unique licorice flavor, and stellar nutrition, fennel bulbs deserve a place in any healthy diet. Incorporate them along with other low-calorie vegetables as part of an overall balanced diet and active lifestyle.

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