Japanese go bananas over latest fad diet

"Yes, we have no bananas, we have no bananas today."

The lyrics play in the background as the YouTube video pans across bare shelves that used to display bananas in Japan's grocery stores. Some days there really are no bananas -- demand has skyrocketed, thanks to "The Morning Banana Diet." In the past few months, banana sales in Japan have increased 40 percent, though so far there has been no significant increase in banana demand in other countries.

The diet, developed in Japan, is relatively simple. For breakfast, eat a raw banana (or bananas) and sip lukewarm water. Eat a normal lunch and dinner while drinking lukewarm water. It's OK to have a sweet midafternoon snack, but otherwise avoid dessert as well as dairy and alcohol. Eat dinner by 8 p.m., go to bed before midnight and exercise if you feel like it. Theories about bananas and weight loss mention the fruit's enzymes and fiber, which may speed digestion.

But nutrition experts are dismissing it as a "fad diet," arguing that if people have lost weight in the short term, it's probably because following the diet means consuming fewer calories.

"There is no magic bullet, no magic food or one certain thing that's going to help someone lose weight," said Brenda Navin, a registered dietitian and personal trainer at Woodwinds Health Campus in Woodbury. Claims that one "miracle" food holds the answer have led to such fad diets as the cabbage soup diet, grapefruit diet, lemonade diet and even a cookie diet.

"When you think about a diet, it needs to be a diet for life," said Lisa Harnack, nutritional epidemiologist and associate professor at the University of Minnesota's School of Public Health. "I'm not so sure eating bananas for breakfast is something you could do for the rest of your life."

But when people are desperate, they grab onto the hope that there's a quick and easy solution for weight loss, said Sharon Lehrman, a registered dietitian with a private practice in St. Louis Park. "It's just easier to do [a fad diet] than to try and reduce portions, plan your meals better, bring your lunch instead of going out to eat every day and do all the things that make sense for long-term good health."

Before throwing any more punches at the bruised banana diet, the nutritionists defend the fruit itself as being healthful, and Lehrman said that at least this diet isn't harmful like some others.

Indeed, bananas are a good source of dietary fiber, potassium and vitamins B6 and C. Here's a breakdown of four banana diet tenets:

Eat raw bananas for breakfast. Bananas pack lots of potassium and fiber and few calories (a medium banana has 100 calories). Most Americans don't eat enough vegetables or fruits, so eating more fruit is a good idea. However, different fruits have different nutrients, so variety is essential. Bananas are high in carbohydrates, and Lehrman said people tend to do better with a high-protein breakfast. "Protein satisfies you longer and makes you feel more full. I'd recommend a more balanced breakfast with protein, some carbohydrate and some healthy fat," she said. High carb intake is especially bad for people with blood sugar issues or insulin resistance.

Sip lukewarm water with meals. "I've never heard of any studies that show room-temperature water has any special properties compared to cold water or hot water," Harnack said. On the other hand, drinking water is obviously good for you, and if water replaces soda or alcohol as your beverage of choice, that's a great step toward better health, Lehrman said.

Eat your normal lunch and dinner. Not necessarily a good idea. "People need to watch out for saturated fat, trans fat and too much sodium," Harnack said. Eating whatever you want for lunch and dinner could lead to overeating and undernourishment if you don't eat balanced meals with vegetables and fruits, complex carbohydrates, lean protein and healthy fats.