What is the Banana and Tea Diet?

January 7, 2026 •

4 min read

Around 2008, the Morning Banana Diet took Japan by storm after an Osaka pharmacist’s husband reportedly lost significant weight on the plan. But what is the banana and tea diet and does it really work for weight loss, as proponents claim?

Quick Summary

This overview details the viral Japanese diet, focusing on its specific breakfast rules of eating raw bananas and drinking unsweetened tea, along with its mindful eating principles and potential outcomes.

Key Points

Origin: The diet began in Japan around 2008, created by a pharmacist and popularized by her husband's success.
Breakfast Rules: Consume raw bananas and room-temperature water or unsweetened tea until you feel 80% full.
Mindful Eating: The diet emphasizes chewing food thoroughly and paying attention to hunger and fullness cues.
Lifestyle Changes: It encourages eating an early dinner, avoiding late-night snacking, and getting enough sleep.
Lacks Scientific Proof: There are no clinical studies to validate the diet's effectiveness for weight loss, and it relies heavily on anecdotal evidence.
Potential Risks: Concerns exist regarding nutrient deficiencies, blood sugar spikes, and potential digestive discomfort due to its restrictive nature.

Origin of the Morning Banana Diet

The diet often referred to as the banana and tea diet is officially known as the Morning Banana Diet or 'Asa-Banana Diet'. It was created in 2008 by Japanese pharmacist Sumiko Watanabe for her husband, Hitoshi, who claimed to have lost 37 pounds on the plan. Hitoshi then posted about his success on the social networking service Mixi, leading to a viral sensation across Japan. The diet's popularity became so immense that it caused a temporary banana shortage in some Japanese cities. The 'tea' component refers to the optional morning beverage, often unsweetened green tea, which is part of the morning ritual alongside the bananas.

How the Diet Works: The Rules and Principles

The Morning Banana Diet is not a strict, calorie-counting plan but a set of simple, easy-to-follow rules designed to encourage healthier habits. The core of the plan revolves around the breakfast meal, with some guidelines for the rest of the day.

The Daily Rules

Breakfast: Eat as many raw bananas as you want until you feel full, accompanied by room-temperature water or unsweetened tea. The bananas must be raw; cooked or frozen bananas are not permitted. Chewing thoroughly and mindfully is encouraged.
Lunch and Dinner: The diet is famously flexible for these meals. You can eat what you normally would, but it is recommended to stop eating when you feel 80% full. Japanese food, particularly rice, is suggested, though not required.
Snacks: Only one snack is allowed per day, typically in the afternoon. Sweet snacks are permitted, but only at this time.
Early Dinner: The last meal of the day should be eaten before 8 p.m..
No Restrictions on Certain Foods: The diet recommends avoiding dairy, alcohol, caffeine, and ultra-processed foods.
Sleep: Going to bed before midnight is advised, as sufficient sleep is deemed important for weight loss.

Proposed Weight Loss Mechanisms

The diet's supposed effectiveness is linked to several factors. Bananas are rich in fiber and resistant starch, which increase satiety and can reduce overall calorie intake throughout the day. The simple, routine breakfast also prevents unhealthy, high-calorie breakfast choices. Additionally, mindful eating habits, the early dinner, and emphasis on sleep contribute to a healthier lifestyle that can lead to weight loss.

Potential Benefits and Risks

While the diet promotes some healthy habits, it is essential to consider the pros and cons.

Potential Benefits

Increased Fiber Intake: Bananas are a good source of fiber, which helps with digestion and feelings of fullness.
Simple and Easy: The rules are straightforward, making the diet easy to follow for many.
Encourages Mindful Eating: The focus on chewing thoroughly and eating until 80% full helps practitioners tune into their body's signals.
Incorporates Healthy Habits: Early dinner and early bedtime promote better sleep and digestion.

Risks and Considerations

Lack of Scientific Evidence: No clinical studies prove the diet's effectiveness for weight loss beyond general calorie restriction.
Nutrient Deficiencies: Relying heavily on bananas can lead to a lack of other essential nutrients, like protein and healthy fats, necessary for a balanced diet.
Blood Sugar Concerns: The high sugar content in bananas can cause blood sugar fluctuations, especially in ripe bananas, which is a concern for people with diabetes.
Digestive Issues: The high fiber in bananas can cause bloating, gas, and constipation in some individuals.
Limited Long-Term Success: Like many fad diets, there is a risk of the 'yo-yo effect' once a person stops following the restrictive breakfast plan.

The Morning Banana Diet vs. a Balanced Breakfast


Feature	Morning Banana Diet	Standard Balanced Breakfast
Carbohydrates	Focus on simple sugars and resistant starch from raw bananas.	Balanced mix of complex carbs (oats, whole grains) and natural sugars.
Protein	Generally absent, leading to potential nutrient deficiency.	Can include lean protein sources like eggs, Greek yogurt, or nuts.
Healthy Fats	Minimal to none in the breakfast, lacking essential fatty acids.	Can include healthy fats from nuts, seeds, or avocado.
Satiety	Fiber helps with fullness, but can be less sustained without protein and fat.	Protein, fat, and fiber combine to provide longer-lasting satiety.
Nutrient Variety	Limited to the vitamins and minerals in bananas.	Offers a wide range of vitamins, minerals, and antioxidants from diverse foods.

Who Should Consider the Banana and Tea Diet?

This diet may appeal to individuals looking for a simple, short-term kick-start to healthier eating habits. The emphasis on mindful eating and early dinner can be beneficial for those struggling with late-night snacking. However, it is not a medically supervised or scientifically proven weight loss method. It is not recommended for individuals with diabetes, kidney problems, or anyone with a history of disordered eating. For sustainable and healthy weight loss, a balanced diet incorporating a variety of fruits, vegetables, lean proteins, and whole grains is always a better long-term strategy. As with any dietary change, consulting a healthcare professional is advised.

Conclusion

The banana and tea diet, known as the Morning Banana Diet, is a viral Japanese trend promoting weight loss through a simple breakfast routine. While the inclusion of fiber-rich bananas and healthful teas can offer benefits and encourage mindful eating, the diet is not backed by scientific research. Its restrictive nature raises concerns about nutritional deficiencies and potential for unhealthy eating patterns. Ultimately, sustainable weight loss is best achieved through a balanced diet, regular exercise, and professional guidance. For more detailed information on the diet's specifics and risks, you can read the Morning Banana Diet review from WebMD.

Frequently Asked Questions

While some people report weight loss, there is no scientific evidence to prove the diet's effectiveness. Any weight loss likely results from the overall calorie restriction and healthier habits it promotes, rather than a special property of bananas and tea alone.

The diet can be safe for short periods, but risks such as nutrient deficiencies, blood sugar fluctuations, and digestive issues can occur, especially if followed for the long term or without medical supervision. It is not recommended for people with diabetes or kidney problems.

The diet's original rules state that you should have room-temperature water or unsweetened tea with your raw bananas. In some variations, other single fruits or even milk can be substituted, but this deviates from the core plan.

Banana tea is a separate preparation involving boiling a banana or its peel in water, primarily used for sleep aid and mood improvement. It is not the unsweetened tea option recommended for breakfast in the Morning Banana Diet, which typically refers to green or black tea.

The rules are flexible for lunch and dinner, but followers are encouraged to eat until only 80% full, eat dinner before 8 p.m., and avoid late-night snacking and processed foods.

The creators of the diet emphasize going to bed by midnight, believing that sufficient sleep is crucial for weight loss and overall health, complementing the dietary rules.

Yes. It is always recommended to consult a doctor or registered dietitian before making significant changes to your diet, especially to ensure it aligns with your specific nutritional needs and health status.

Yes, moderate exercise like walking is encouraged. The diet itself does not require intense physical activity, but combining it with regular exercise is recommended for better results and overall health.