Japanese water therapy involves drinking several glasses of room-temperature water every morning when you first wake up.

Online, it’s claimed that this practice can treat a host of problems, spanning from constipation and high blood pressure to type 2 diabetes and cancer.

However, many of these claims have been exaggerated or are not supported by science.

This article reviews the benefits, risks, and effectiveness of Japanese water therapy.

Supposedly, Japanese water therapy gets its name from being widely used in Japanese medicine and among the Japanese people.

It involves drinking room-temperature or warm water on an empty stomach after waking to cleanse the digestive system and regulate gut health, which — according to proponents — can heal a variety of conditions.

In addition, advocates of Japanese water therapy claim that cold water is harmful because it can cause the fats and oils in your food to harden in your digestive tract, thus slowing down digestion and causing disease.

The therapy includes the following steps that should be repeated daily:

  1. Drink four to five 3/4-cup (160-ml) glasses of room-temperature water on an empty stomach upon waking and before brushing your teeth, and wait another 45 minutes before eating breakfast.
  2. At each meal, eat only for 15 minutes, and wait at least 2 hours before eating or drinking anything else.

According to practitioners, Japanese water therapy must be done for different periods to treat different conditions. Here are some examples:

  • Constipation: 10 days
  • High blood pressure: 30 days
  • Type 2 diabetes: 30 days
  • Cancer: 180 days

Though drinking more water may help with constipation and blood pressure, there is no evidence that Japanese water therapy can treat or cure type 2 diabetes or cancer. However, drinking more water may bring along some other health benefits.


Japanese water therapy involves drinking several glasses of room temperature water when you wake up each morning. Adherents claim that this practice can treat a variety of conditions.

Though Japanese water therapy is not an effective treatment for many of the conditions it’s been claimed to improve, drinking more water can still result in some health benefits.

Additionally, following this therapy protocol may result in weight loss because it can cause you to restrict your calorie intake.

Increased water intake

Using Japanese water therapy includes drinking several glasses of water per day, helping you stay adequately hydrated.

There are numerous benefits to adequate hydration, including optimal brain function, sustained energy levels, and body temperature and blood pressure regulation (1, 2, 3, 4).

In addition, drinking more water may help prevent constipation, headaches, and kidney stones (5, 6, 7).

Most people get enough fluid by simply drinking to satisfy their thirst. However, if you’re very active, work outdoors, or live in a hot climate, you may need to drink more.

Lower calorie intake

Practicing Japanese water therapy may help you lose weight via calorie restriction.

First, if you replace sugar-sweetened beverages like fruit juice or soda with water, your calorie intake is automatically decreased — potentially by several hundred calories per day.

Additionally, sticking to regimented eating windows of only 15 minutes per meal, after which you can’t eat again for 2 hours, may restrict your calorie intake.

Finally, drinking more water may help you feel fuller and make you eat fewer overall calories from food.

All this said, research on the effect of water intake on weight loss is mixed, with some studies finding positive results and others seeing no effects (8).


There are several health benefits of being adequately hydrated. In addition, drinking more water may help you lose weight through calorie restriction.

Japanese water therapy is associated with potential side effects and precautions.

Water intoxication, or overhydration, can occur when you drink an excessive amount of water in a short period of time. It’s caused by hyponatremia — or low salt levels — in your blood due to salt being diluted by excessive fluid (9).

It’s a serious condition that can result in death, but it’s rare in healthy people whose kidneys are able to quickly get rid of excess fluid. People at increased risk of hyponatremia include those with kidney problems, endurance athletes, and people who abuse stimulant drugs (9).

To be safe, don’t drink more than about 4 cups (1 liter) of fluid per hour, as this is the maximum amount that a healthy person’s kidneys can handle at once.

Another downside of Japanese water therapy is that it can be excessively restrictive due to its guidelines on the timing of meals and eating within a 15-minute window.

If you’re trying to lose weight, excessive calorie restriction can lead to rebound weight gain after finishing the therapy. Restricting calories reduces the number of calories you burn at rest and causes spikes in the hormone ghrelin — which increases feelings of hunger (10, 11).

What’s more, there is a risk of overeating or eating too quickly within the allotted 15-minute eating windows, especially if you feel more hungry than normal by the time you’re able to eat. This can cause indigestion or lead to weight gain.


There is a risk of water intoxication, or hyponatremia, from Japanese water therapy. Additionally, excessively restricting calories while practicing the therapy may lead to rebound weight gain once you finish the practice.

Japanese water therapy is touted as a cure for a variety of conditions from constipation to cancer, but there is no evidence to support this.

The therapy supposedly cleanses your gut and helps regulate gut health, but no existing research confirms this. Water intake has a much smaller effect on the balance of gut bacteria than other factors like diet (12).

Furthermore, there appear to be only few upsides to avoiding cold water. Cold water does decrease your gastrointestinal temperature and may slightly increase blood pressure in some people, but it will not cause fats to solidify in your digestive tract (13, 14).

Before you consider using Japanese water therapy to treat a condition or disease, you should discuss it with your healthcare provider.

It’s also important to note that Japanese water therapy should not be used as a replacement for medical care from a licensed healthcare professional.


Although there are some benefits to being adequately hydrated, Japanese water therapy has not been shown to treat or cure any disease. It should not be used as an alternative to medical care from a healthcare professional.

Japanese water therapy involves timing your meals and water intake, supposedly cleansing your gut and healing disease.

However, scientific evidence does not indicate that it works.

There are several benefits to adequate hydration, but Japanese water therapy cannot treat or cure any medical condition.

If you’re dealing with a condition with which Japanese water therapy is claimed to help, you should consult your healthcare provider.