Hiromi Shinya Diet: What You Need to Know

This eating plan is considered a fad diet. Fad diets often promote quick weight loss that is unsustainable and may severely restrict what you eat. They may be harmful and generally do not have long-lasting health benefits. Talk to your healthcare provider before you make any major changes to how you eat.

The Hiromi Shinya diet calls for eating a diet rich in plant-based foods with few or no dairy products or animal-based protein as the key to better health — better gut health in particular. It was developed by the gastroenterologist Hiromi Shinya, MD, and detailed in his 2007 book The Enzyme Factor.

Dr. Shinya’s theory is based on the premise that these habits will boost your concentration of digestive enzymes, leading to a healthier digestive tract and a lower overall risk of gastrointestinal issues.

How Does the Hiromi Shinya Diet Claim to Work?

This eating plan purports to improve your overall health by helping your body fully digest your food and absorb its nutrients.

It calls for sourcing 85 to 90 percent of your food from plants, with approximately 50 percent of this from whole grains, beans, and legumes; 30 percent from colorful vegetables; and the remainder coming from two servings of fruit and ¼ to ½ cup of nuts or seeds per day.

Fifteen percent or less of your diet should contain animal protein. Raw and fermented foods are emphasized.

While it isn’t the focus of this diet, chances are you will lose weight by eating this way and choosing healthy foods over processed ones.

What Can You Eat on the Hiromi Shinya Diet?

There are specific foods you’ll want to load up on when following the Hiromi Shinya diet.

Foods to Include

Shinya recommends consuming:

• Two to three cups of water first thing in the morning. Shinya recommends drinking a type of alkaline water that purports to counteract acidity in your body. It’s also important to drink 8 to 10 glasses of water throughout the day.
• A piece of whole fruit, such as an apple or an orange, for breakfast
• More water and a light lunch, such as vegetable broth or miso soup
• Dinner should consist of lightly steamed vegetables such as spinach, snow peas, carrots, broccoli, and bean sprouts paired with brown rice and no more than 3 or 4 ounces of poultry, eggs, or low-mercury fish such as sardines, anchovies, or wild salmon.
• Foods that provide digestion-supporting enzymes, such as: raw fruits; raw, lightly steamed, or sautéed vegetables; sea vegetables; and fermented foods such as kimchi, pickled vegetables, natto, tempeh, and miso
• Whole food sources of healthy oils such as olives, avocados, nuts, and seeds.

The Hiromi Shinya diet also calls for chewing food thoroughly, as in 30 times before swallowing, in order to aid digestion. One previous review found three of five studies included in the research determined that increasing the number of chews per bite increased relevant gut hormones and also decreased food intake and hunger.

Foods to Avoid

Foods that can upset the stomach or are slower to digest are discouraged on the Hiromi Shinya diet, including:

• Milk and dairy products
• Red meat
• Animal-based foods in high amounts
• Refined vegetable oils, especially from soy, corn, and safflower
• Chocolate
• All types of black or green tea
• Alcohol
• Coffee
• Sweets

Potential Benefits of the Hiromi Shinya Diet

There is no published research on the Hiromi Shinya diet, but there are potential benefits including weight loss and broader health implications.

First, it's likely that you will lose weight on Shinya's diet, because it calls for reducing your intake of fat, refined grains, and added sugar while significantly increasing your consumption of whole grains, fruits, and vegetables. One study found that people who ate a minimally processed diet prepared at home for eight weeks lost twice as much weight as those who stuck with an ultra-processed diet.

Also, the overall premise behind the diet — that without a proper amount of digestive enzymes, your body struggles to break down food and absorb nutrients in the food — is accurate, according to Johns Hopkins Medicine.

Eating this way may make it easier for you to manage chronic conditions. For instance, research has shown that limiting your red meat, as Shinya advises, may decrease your risk of death from heart disease, stroke, or diabetes.

The diet also emphasizes regular moderate exercise, six to eight hours of sleep nightly, meditation, and time each day for personal enjoyment. Other experts agree. The American Heart Association, for instance, lists eating right, being active, getting enough sleep, practicing mindfulness, managing stress, and connecting socially as keys to a healthy lifestyle.

Potential Risks of the Hiromi Shinya Diet

There are some potential downsides to eating this way, including:

• Nutrient Deficiencies Unless your daily meals are carefully planned or you regularly take dietary supplements, Shinya's plan may leave you vulnerable to deficiencies in calcium, vitamin B12, vitamin D, iron, zinc, omega-3 fatty acids, and iodine. These deficiencies are a risk for those who avoid meat and animal products, according to Mayo Clinic.
• Lack of Scientific Evidence Although the diet is likely to yield benefits, the book doesn’t cite any scientific studies backing up Shinya's theory that certain foods deplete enzyme concentrations and harm your health. There’s also a lack of evidence that specific enzyme-rich foods aid digestion, though simply prioritizing healthy foods should be enough to support your digestive enzymes.
• Social Isolation The plan may be too restrictive for some people to maintain, particularly if other family members aren't adhering to the same guidelines.

Is the Hiromi Shinya Diet Right for You?

This diet is considered a fad diet and lacks scientific support for the purported health benefits. It may call for severely restricting what you eat and may also lead to nutrient deficiencies. It’s important to reach out to your healthcare provider before you start any diet.

The Takeaway

• The Hiromi Shinya diet aims to improve your gut health by maintaining proper digestive enzyme concentrations.
• It involves eating mainly whole grains, vegetables, fruits, and legumes, plus a very small amount of fish, poultry, or eggs.
• Red meat, dairy, refined oils, and sweets are discouraged.
• While these eating principles are generally recommended in a healthy diet, there isn’t enough scientific evidence to show whether this plan is safe and effective.

Additional reporting by Moira Lawler.