Liquid Diets

Vinegar and Water Diet
It originated from the ancient Egyptian period and was made popular by Lord Byron. It was believed that the acetic acid in vinegar may be beneficial to the body but does not aid in weight loss. In addition, this diet was attempted by Fergie, who claimed that this diet helped her tone her stomach.

Liquid Protein Diet
This diet originated in the 1930s. According to the Food and Drug Administration in 1977, 58 deaths were reported, all of which were adults who were following this strict liquid protein diet. This diet lacks the essential nutrients and solid food that is a basic necessity. 

Second-generation liquid diets are claimed to be safe and nutritionally complete as they are supervised by medically-certified professionals and patients are given the necessary vitamin and mineral supplements. According to the New York Times story, one of the liquid protein diet program was specially mentioned by Oprah Winfrey and boosted the popularity of this particular diet.

Third-generation liquid diets come in the form of powders or cans of diet drinks. Basically, this diet recommends the consumption of a shake for breakfast and lunch, while eating whole food for dinner, with the allowance of snacks in between each meal.