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Leeks have traditionally been viewed as a diet food for French women.

French women would boil the leeks and drink the water to make what’s known as magical leek soup.

However, you wonder whether there truly is any magic to this drink for fat loss or if it’s merely a fad.

This article explains how to make magical leek soup and dives into the research as to whether the diet works for fat loss.

leek soup diet

What is magical leek soup?

It’s unclear where and by whom the magical leek soup originated.

However, in the early 2000s, Mireille Guiliano speaks of the diet in her nationwide bestseller book called, French Women Don’t Get Fat: The Secret of Eating for Pleasure.

In her book, Guiliano — a slender French girl — tells her story of going to America as an exchange student and returning fat.

Dismayed, she visited her family physician, “Dr. Miracle,” who gave her several recipes, but none were more important than the magical leek soup recipe, she claimed.

Guiliano explained that leeks are a mild diuretic, and drinking the leek soup every 2–3 hours, one cup at a time, for 48 hours would provide immediate fat loss.

Aside from the soup, nothing else is allowed during these 48 hours.

Here’s Guiliano’s magical leek soup recipe:

  1. Starting with 2 pounds of leeks, cut off the top dark green leaves and the root.
  2. Slice the leeks and rinse under cold water in a colander to remove any dirt.
  3. Put leeks in a large pot and cover with water.
  4. Bring to a boil and simmer with no lid for 20–30 minutes.
  5. Strain the liquid into a container with a tightly-sealed lid.
  6. Drizzle with a few drops of extra-virgin olive oil and lemon juice and season sparingly with salt and pepper. Add chopped parsley if you wish, and voilà!

Store the juice in your fridge and drink warm or allow to cool to room temperature after reheating.

Magical leek soup is different from the classic French potato leek soup, the classic base soup in French cuisine.

Potato leek soup — or potage parmentier — consists of pureed leeks and potatoes as well as other ingredients like broth, heavy cream, garlic, herbs, and spices.

Can it help you lose weight?

Since the magical leek soup diet calls for nothing but the broth for 48 hours, you’re likely to experience some weight loss.

One cup of the broth contains around 15 calories per cup (240 mL) (1).

Assuming you drank 16 cups of the leek soup over the recommended 48 hours, you would only be consuming 240 calories.

Consuming such few calories over two days puts your body in a fasting state.

During this state, glycogen — your body’s storage form of carbohydrates — and water is depleted from your muscles and liver (2).

This loss of glycogen and water is why people who start a low-carbohydrate or ketogenic diet experience rapid weight loss in the first week (3).

As such, most — if not all — of the weight you lose with the magical leek soup diet is from losses in glycogen and water — not fat.

Once you resume your normal diet after the recommended 48 hours, you will replenish your glycogen stores and likely regain all the weight you lost.

Therefore, the magical leek soup diet is not an effective or sustainable weight loss solution.

Still, some people may use the magical leek soup diet as a way to “reset” or “detox” after eating unhealthy.

While doing so may temporarily help you feel better, it’s unnecessary and could lead to disordered eating or eating disorder (4).

Health benefits of leeks

Although following the magical leek soup diet won’t result in sustainable weight loss, leeks are rich in nutrients.

Leeks belong to the Allium genus, the same genus as onions, chives, scallions, and garlic.

Allium vegetables are rich in organosulfur compounds, which have strong antioxidant, anti-inflammatory, and immune-strengthening effects (5, 6).

Owing to these properties, eating a diet rich in leeks and other Allium vegetables has been associated with a reduced risk of certain cancers and may offer protective effects against heart disease, diabetes, and other inflammatory conditions (7, 8, 9, 10).

Leeks also contain many vitamins and minerals.

One cup (170 grams) of cooked leeks provides (1):

  • Vitamin K: 73% of the daily value (DV)
  • Copper: 25% of the DV
  • Vitamin B6: 24% of the DV
  • Folate: 24% of the DV
  • Iron: 21% of the DV
  • Vitamin C: 20% of the daily value (DV)
  • Vitamin A: 18% of the DV
  • Vitamin E: 14% of the DV
  • Magnesium: 12% of the DV
  • Thiamin: 8% of the DV
  • Calcium: 8% of the DV
  • Potassium: 7% of the DV
  • Phosphorus: 5% of the DV

How to prepare and enjoy leeks

Leeks are versatile, allowing you to cook and incorporate them into your diet in a variety of ways.

Mostly just the white and light parts of the leeks (the stem) are eaten since the darker green leaves are bitter.

But many people use the leaves to add an oniony flavor to homemade stock.

You can enjoy leeks cooked or raw.

Here are the steps to cut leeks:

  1. Chop off the stringy roots and dark green leaves.
  2. Slice the leeks in half lengthwise.
  3. Chop the white and light green parts into thin half-moons.
  4. Add to a colander and rinse under cool water to remove any dirt.
  5. Blot them dry using a paper or kitchen towel before you start cooking.

Here are a few ways to enjoy leeks:

  • Roast them. Clean and halve a few leeks and add them to a pot roast or pan of roasted vegetables.
  • Add to a salad. Toss in some slices of raw leeks to add more crunch to your salad.
  • Make a soup. Try making potato leek soup using this easy recipe.
  • Mash. Add leeks to your mashed potatoes by dicing the white part and adding to the potatoes as they begin to boil.

Like other vegetables, steaming leeks rather than boiling them will increase their retention of beneficial nutrients (11).

The bottom line

The magical leek soup diet involves drinking leek broth every 2–3 hours for 48 hours — no other food or beverage is allowed.

Consuming such few calories will result in weight loss, but this weight loss is from glycogen and water loss, not fat.

However, while magical leek soup is an ineffective and unsustainable approach to fat loss, leeks contain several beneficial nutrients.

You can enjoy leeks raw or cooked and their versatility allows you to easily incorporate them in many dishes.


Gavin Van De Walle, MS, RD, LN
Gavin Van De Walle, MS, RD, LN

Gavin Van De Walle holds a master's degree in human nutrition and bioenergetics. He is a registered dietitian who aims to arm the public with evidence-based nutrition recommendations so they can make their own educated and informed health decisions.