Banana importer, Dole Japan Company, has increased supplies by 25 per cent over the corresponding period last year but is still struggling to meet demand. Consequently, banana prices are soaring but with the celebrity endorsements and more than 600,000 copies of the diet books sold, demand for the fruit shows no signs of slowing.
Adherents of the diet love it for its simplicity and reported success.
Essentially, the regimen requires dieters to start the day with a raw banana and a glass of room-temperature water. After that, they're free to eat whatever they want for the rest of the day - except for sweets. Desserts with meals are banned and just one sweet snack in the mid-afternoon is allowed. Alcohol consumption is discouraged and early dinners (before 8pm) and taking to bed before midnight are the diet's only other strictures.
But perhaps the diet's greatest appeal lies in its easy-going approach to exercise. It counsels weight-watchers to work out only if they want to and then to exert themselves in the least stressful way possible.
The craze reached a new zenith last month when the Tokyo Broadcasting System aired a television program in which the very hefty former Japanese opera singer Kumiko Mori attributed a sudden seven-kilo weight loss to the diet. Bananas have been in scarce supply on Japanese supermarket shelves ever since.
The Morning Banana Diet was developed by an Osaka pharmacist with a keen interest in Chinese herbal medicine. Sumiko Watanabe devised the dietary regime for her husband, who had become exasperated by his inability to lose weight by more orthodox means. Mr Watanabe is now a lean 59 kilos at 175 centimetres and attributes the diet's magic to its stress-free approach, writes Mindy Laube in Australian newspaper The Age.
Nutritionists are divided on the efficacy of the diet but bananas are a rich source of resistant starch, a type of fibre found in carbohydrate-dense foods such as potatoes, corn, barley and bananas - especially slightly unripe fruit. The indigestible starch is being touted as a wonder diet food by advocates as it is said to help induce feelings of saiety and increase the body's fat-burning capacity.