Though leeks are a national emblem of Wales, it was the French who made them into a diet fad.

These tall, white and green plants are a root vegetable in the allium family (which includes garlic, chives and onions). Leeks contain lots of organosulfur compounds, which are organic molecules containing sulfur. These compounds are what give allium vegetables their strong odors. But they also offer strong antioxidant and anti-inflammatory properties, which can support the immune system and overall health.

Lisa Young, a nutrition consultant and author of “Finally Full, Finally Slim” and “The Portion Teller Plan,” says that “leeks are rich in the antioxidants kaempferol and allicin, which can help fight oxidation leading to chronic disease.” Oxidation is the process by which cells can be damaged due to daily wear and tear or exposure to toxins.

Antioxidants help combat this process, and are thought to reduce the risk of diseases like diabetes, heart disease and cancer.

With a milder flavor than onions or garlic, but still a bit of pungent bite, leeks work well in a range of dishes. But it’s the water used to boil them that’s the core aspect of the leek soup diet.

The leek soup diet, and more specifically the soup itself, is sometimes referred to as magic leek soup. Reportedly, generations of French women have used it as a quick-start weight loss tool that mimics fasting and can help dieters shed a few pounds quickly.

Both magic leek soup and the leek soup diet approach to weight loss have gained renewed attention after being mentioned in season two of the popular Netflix show “Emily In Paris.”

This diet is all about the soup, which is essentially just the water used to boil the leeks.

The recipe couldn’t be much simpler: cut the green ends and the stringy roots of the leeks off and discard them. Slice the white section of the leek lengthwise, and rinse under running water to remove any soil that may have lodged between the layers.

Put the leeks in a large pot and cover them with water. Bring to a boil, then lower the heat and let simmer for 20 to 30 minutes.

Once the leeks have cooked, pour off the liquid and reserve it – that’s your leek soup. “The diet calls for drinking 1 cup of leek soup every two to three hours for 48 hours,” Young says.

If you’re very hungry, you can eat a half-cup of the cooked leeks themselves, but the general idea is to forgo solid foods for the 48 hours and drink only the soup during the two-day fasting period that constitutes the leek soup diet.

Some recipes call for adding some flavorings, such as salt, lemon or parsley.

If you have obesity or are carrying excess weight, losing weight may be advisable as it can influence a number of other health metrics. While there’s not a lot of scientific evidence available to support the use of the leek soup diet for overall health improvements, there are some health factors that might be influenced by the weight loss that some dieters experience while using the leek soup diet.

Possible benefits associated with the leek soup diet may include:

A cup of leek soup broth contains about 15 calories, and because it’s all you’ll be ingesting for 48 hours, you may drop a few pounds. This weight loss may be primarily from water weight because you’re not consuming solid foods; as soon as you start eating solid foods again, those lost pounds may creep back on.

That said, a 2014 study noted that soup-eaters had a lower risk of obesity and that they tended to consume higher-quality foods. Eating a low-calorie soup prior to a meal can reduce hunger when the second course arrives, which could lead to lower overall calorie consumption and weight loss. What’s more, because leeks are made up of more than 80% water, they can help you feel fuller with less volume of food.

Leeks also have a mild diuretic effect, meaning they’ll help you flush out excess fluid via increased urine output. This can help you see an immediate decrease in weight, propelling some dieters into a more sustainable, long-term weight loss program.

While the leek soup diet won’t offer lasting weight loss, many people use it as a means of resetting or “detoxing” when starting a new diet. Some leek soup diet enthusiasts believe that by eliminating nearly all foods for a period of time, they can give their digestive tract a chance to rest and reset, but there’s not much evidence to back up this claim.

Antioxidants fight oxidative stress in cells. That’s the daily wear-and-tear stress that our bodies undergo every day. Some studies have indicated that diets high in antioxidants and flavonoids (a type of antioxidant) like those found in leeks and other allium vegetables can lower oxidative stress and the systemic inflammation it causes. This may, in turn, lower the risk for certain diseases such as heart disease, diabetes and some cancers.

Reduced inflammation is also associated with delayed onset of Alzheimer’s disease and other forms of dementia, or perhaps compounds in allium vegetables might one day be used as a treatment for dementia; a 2015 study conducted in India noted that allicin, a molecule found in garlic and other allium vegetables, showed potential to ameliorate the decline of cognitive function and memory in Alzheimer’s disease patients.

You won’t be eating out while on the leek soup diet, as only leek soup is permitted during the 48-hour period over which the diet takes place. The soup is naturally vegetarian, vegan and gluten-free. It’s also dairy-free, unless you add cream, milk or another dairy product to your recipe.

Kids, pregnant people and those with an eating disorder or a history of disordered eating should avoid this diet, as any super restrictive approach to food intake can cause an exacerbation or relapse of symptoms. Athletes and people who are very active should also be cautious, and this diet provides very few calories to fuel physical activity.

Many nutritionists pan the leek soup diet as a fad or gimmick that leaves dieters hungry and more likely to rebound with binge eating after the 48-hour fast has ended.

Young says the leek soup diet “is not a sustainable approach to weight loss.”

Gaby Vaca-Flores, a registered dietitian and founder of Glow+Greens, a nutrition and skin care consultancy based in Santa Monica, California, says that because a typical serving of leek soup can range between 15 and 25 calories, “if you are a cup of leek soup every two to three hours during a typical eating window, you would only consume 90 to 300 calories per day. Consuming such small amounts of calories, even if it’s only for 48 hours, can be harmful and could be indicative of disordered eating behavior.”

She says it can also “trick your body into thinking that ‘I’m fasting’, which will only lead to temporary water weight loss, not fat.”

That said, “leeks are very healthy and contain beneficial nutrients,” Young says. Instead of opting for the leek soup diet, she recommends harnessing the health benefits of leeks by adding them to a “more balanced diet including portion-controlled foods from all of the food groups for long-term weight loss.” Put simply, while the leek soup diet may not be a great choice for lasting weight loss, leeks are a terrific addition to any balanced diet.

Reda Elmardi, a New York City-based registered dietitian and owner of thegymgoat.com, an online training resource, notes that leeks are inexpensive, versatile and “easy to grow from seed and are a great addition to any garden.”

And, as Vaca-Flores says, “there are many ways to enjoy leeks other than in soup. I recommend roasting, steaming or tossing them into a salad.” Adding more leeks to your diet will help you boost your intake of beneficial nutrients without adding too many calories.