With the obesity rate in the United States rising, it's no surprise that diets that claim to work quickly and easily become all the rage. But are they safe?

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.

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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."

Click through the slideshow to see some examples of crash diets that simply don't work.

The master cleanse diet was one of the most popular diets of 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.

Popularized in the 1980’s the cabbage soup diet restricts 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.

The grapefruit diet is one of the oldest fad diets, and has been around since the 1930s. It involves eating fat and protein-heavy meals with a side of grapefruit while eschewing carbohydrates. While not dangerous in its own right, grapefruit has been known to interfere with a variety of medications.

Erroneously attributed to the Israeli Army, the diet is an 8 day low-calorie diet that worked in the short term, but resulted in weight gain as soon as the diet ended. For the first two days, dieters only ate apples. The next two, cheese, followed by two days of chicken and two days of salad.

The feeding tube diet, also known as the K-E diet, involves “eating” through a feeding tube put into your nose for 10 days in order to lose 20 pounds 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 helps dieters shed any unwanted weight.