The morning banana diet is based on the premise that eating only bananas for breakfast and drinking room-temperature water as your main beverage results in weight loss, no matter what you eat the rest of the day.
Hitoshi and Sumiko Watanabe created the morning banana diet, technically called the Asa banana diet. Hitoshi wanted to lose weight and Sumiko, a pharmacist with training in herbal medicine and alternative health practices, suggested the foundation of the diet: bananas and warm water in the morning, and dinner several hours before bedtime. Participants of a Japanese social networking site later refined the diet to some degree. "Time" magazine reported that the demand for bananas caused Dole Japan to increase its imports over 25 percent, with the company still unable to keep enough bananas on the shelves in 2008.
On the morning banana diet, eat as many bananas as you want for breakfast and drink warm water, but don't stuff yourself. Eat only raw and unfrozen bananas. A variant of the diet as described at the Morning Banana Diet website allows substitutions of other fruit. You can eat other food before lunch if you get hungry—one of the diet's inventors sometimes ate a rice ball for a mid-morning snack.
Eat anything you like for lunch or dinner, but eat only until you are satisfied, not uncomfortably full. The original diet prohibits dairy products, but revised versions allow them. A mid-afternoon sweet snack such as chocolate or cookies is acceptable, but ice cream or donuts are not recommended. A salty snack is all right as well, but it should be something healthful like seaweed snacks or a rice ball, not potato chips. Eat dinner at least four hours before bedtime. The latest you should go to bed is midnight, and in that case, have dinner before 8 p.m., advises Morning Banana Diet.
Room-temperature water is the primary beverage allowed on the morning banana diet. Take small sips of the water during meals, but do not use it to wash down food. No minimum amount is required, and you shouldn't drink it in excess. Outside of meals, you may drink non-caloric beverages including tea, coffee and diet soda, although this is not preferable. The original diet prohibits alcohol, but modified versions allow beer or wine on social occasions.
Several theories explain why the morning banana diet may be effective. One belief is that bananas may improve digestion and boost metabolism, according to the website Every Diet. Another is that bananas contain resistant starch, a fiber-like substance that resists digestion, promotes a feeling of fullness and may block some absorption of carbohydrates. Drinking warm water leads to more frequent bowel movements and improvement of constipation, and limiting beverages to non-caloric choices reduces calorie intake. In addition, reducing eating outside of meals stops grazing during the day and mindless nighttime eating.