Soon-to-be brides looking to fit into their wedding dresses are increasingly turning to a crash diet based on feeding tubes that doctors warn is unhealthy and potentially dangerous. The K-E diet advocates that dieters feed through feeding tubes into their nose for 10 days on the promise of losing up to 20 pounds (9 kilograms) quickly.

The feeding tube runs from the nose into the stomach and supplies dieters with 800 calories per day from protein, fat and water. Without carbohydrates, the body enters a state called ketosis in which dieters burn fat instead of sugars and help brides-to-be shed any unwanted weight.

It is a hunger-free, effective way of dieting, Dr. Oliver Di Pietro, an internist from Bay Harbor Islands, Fla., told ABC News. Your hunger and appetite go away completely, so patients are actually not hungry at all for the whole 10 days. That's what is so amazing about this diet.

Other doctors caution that such a low-calorie diet can cause serious health problems. The 800 calories per day dieters receive is a far cry from the 1,900 calories per day the U.S. Department of Agriculture recommends daily for women between the ages of 19 and 50 .

Any extreme low-calorie diet is associated with side effects, kidney stones, dehydration, headaches, Dr. Louis Aronne, director of the Comprehensive Weight Control Program at New York-Presbyterian Hospital, told the New York Times. And if you lose muscle mass and water, what's the point of that?

Healthy weight loss consists of losing approximately 2 pounds (1 kilogram) per week, according to the National Institutes of Health. Crash diets that promise to help you lose weight at a faster rate than 2 pounds per week rarely lead to permanent weight loss and often don't provide all the nutrients your body needs, the institute states on its website.

Crash diets restrict what foods you can and can't eat, but when you're eating less than 1,000 calories per day, you'd lose weight no matter what you eat, Donald Hensrud, chairman of preventive medicine at the Mayo Clinic, told US News & World Report.

People could eat nothing but jelly beans and if they were eating just a small amount, they would lose weight, he said. You might be able to get away with it for a period of time, but the more restrictive [the diet] is-and the longer you follow it the greater the risks.

Risks of crash diets not only include nutritional deficiencies and physical health issues, but also emotional problems, according to Cheryl Forberg, staff nutritionist for NBC's The Biggest Loser.

You can lose muscle mass on near-starvation diets -- the body starts to feed on protein for sustenance, she told US News & World Report. Don't be surprised if you're more snappish; irritability, depression and inability to handle everyday stress are travel companions of low-cal diets.

Crash diets are often referred to as fad diets because they go in and out of style. One of the most popular crash diets was the master cleanse diet, popularized in the 1970s. Dieters were not allowed any food over the course of 10 days, instead having to consume a variety of drinks including lemonade made from lemons, maple syrup and cayenne pepper.

Another popular crash diet was the cabbage soup diet, which became popular in the 1980s, restricted dieters to little more than cabbage soup over the course of a week. Although the diet promised fast weight loss, the recipe for the soup is very high in sodium and contains little to no protein, making it an unhealthy diet to sustain. Many people who tried the diet complained of feeling weak and light-headed.

While crash diets may help you lose weight in the short-term, they are dangerous in the long run, Jim White, spokesman for the American Dietetic Association, told US News & World Report.

[Crash diets] patch things up instead of addressing the larger issues: cutting down portions, eating five or six meals a day to speed up your metabolism, and getting a variety of foods, he said.

A healthy diet consists of a balanced diet and exercise, according to White.

If you need to look good for a wedding or class reunion, he said, do yourself a favor and plan ahead.