Oct. 25, 2008 -- Fumiko Satake, a 29-year-old Tokyo wife, picked up one bunch of green bananas at a supermarket in downtown Tokyo -- not because she preferred unripe bananas, but because that was all she could get her hands on.

"I came to the store early today so that I could get bananas," Satake sighed. "And there are hardly any here. It has been this way for the past few months."

The banana has long been a fruit of choice for many Japanese. In 2007, the Japanese consumed 970,000 tons of bananas. But a new diet has swept across the nation and become the culprit for the sudden spike in banana consumption, and a shortage at grocery stores.

"My husband has lost about six pounds since he started the morning banana diet a few months ago," Satake said. "I am not sure how much the fruit did for me, but my husband has been following this diet and he needs his bananas."

The morning banana diet debuted on a few TV shows over the past six months. During one program that aired in September, a Japanese singer said she lost roughly 15 pounds in one and a half months on the banana diet.

The basic instructions are simple. Eat as many bananas as you want in the morning with room-temperature water. Enjoy a regular lunch and dinner (but finish dinner before 8 p.m.) and try to go to bed before midnight. You could snack in between meals (not right after each meal) and even have alcohol -- as long as it's in moderation.

"I never imagined my posting on the Internet could change so many peoples' lives," said Hitoshi Watanabe, a 31-year-old former employee at a printing company in Tokyo.

Watanabe managed to lose 38 pounds by using the diet regimen that his wife, Sumiko designed for him.

"I started to gain weight as I started to work full time after college," Watanabe said. "I guess a combination of overtime, late dinner, lack of exercise and stress all contributed to my weight gain."

Watanabe tried to exercise and lost a few pounds, but then hit a plateau.

"I did not know what else to do," he said.

A Diet Easy to Live With

Sumiko, a 31-year-old pharmacist, studied preventive medicine and came up with the method for her then-boyfriend.

"I just wanted something that would not torture me," said Watanabe. "Bananas are rich in vitamins and minerals, but low in calories. They also contain properties which fight the build-up of acids. They are readily available and reasonably priced. And you do not need any utensils to eat them. It is just so easy and I thought I could give it a try."

Watanabe lost four pounds in the first month and kept losing similar amounts each month until he lost a total of 38 pounds in less than one year.

"I did not know losing weight could be this easy," Watanabe said. "So, I just wanted to share this with other people."

That was when he put the banana diet information on mixi, the largest social networking service in Japan, where registered users can access information both from computers and cell phones. "I did not know so many people would show an interest. The response was just overwhelming."

Watanabe certainly did not mean to create a banana shortage all over Japan, but that is exactly what the nation experienced.

Akihiro Takenaka, a produce manager of a Tokyo supermarket, Ozeki, said the demands for bananas are still high and the supply simply cannot catch up.

"I have been in the produce business for almost 20 years and I have never seen this kind of phenomenon," said Takenaka. "We usually purchase 15 cases of bananas every day, but we have not been able to secure that amount for the past few months. We are lucky if we get five cases. "

Hiromi Otaki of Dole Japan Co., the top banana importer to Japan, said the company has increased imports by 25 to 27 percent in the last few months.

"Summer and winter are tough seasons to sell bananas," said Otaki. "Summer has been especially a tough time for us, but this past summer was just incredible."

Morning Banana Diet Hits Fad Status

Japanese have gone through their share of diet fads -- from apple and cocoa to fermented beans. When one item is taken up by the media, Japanese rush to stores and empty the shelves. What makes the banana diet stand above the rest is its longevity.

"This fad started early this year and might have peaked this summer, fall," said Miwa Tamura, a national registered dietitian. "But there are still a lot of people who follow this method."

Roughly 2,400 people have signed up to access Watanabe's site. Many of them post a "diary" to show their progress.

"One man has kept writing in for more than 700 days so far," Watanabe said. "He had lost about 19 kg (41 pounds) so far."

Watanabe encourages people to start a "buddy" system to help monitor each other's progress.

"I had my wife to help me, but being on a diet by yourself can be a lonely thing," said Watanabe. "I recommend people record their progress and share that with people."

Losing weight was not the only fruit of Watanabe's labor. The banana diet plan was so appreciated, Watanabe had a few book offers. Four books came out this year alone -- more than 900,000 copies sold so far. His first book has been translated and sold in Korea and Taiwan. Watanabe said the book will soon be sold in a few more Asian countries.

Although Watanabe hopes the banana diet can be as life-changing for others as it was for him, he warns that eating bananas alone will not directly lead to weight reduction.

"People tend to focus just on bananas and forget other things I mention, such as finishing dinner before eight or going to bed before midnight," Watanabe said. "These help your body and mind to rest, which is also important for weight management. You will need to create an environment where body and mind can be released from stress. Weight reduction also means stress reduction. Bananas are not your magic wand, but they could help you. They did for me."