Why Some Doctors Warn Against The Blood Type Diet

There's no shortage of fad diets and trendy meal plans promising to help you shed pounds in months — or even weeks. One popular example is the blood type diet, which first gained traction after the release of the 1996 book "Eat Right 4 Your Type," written by naturopathic physician Dr. Peter J. D'Adamo. According to WebMD, the diet's concept is simple: people with different blood types should follow different diets to maximize health and weight loss. People with type A blood are said to have sensitive systems and should eat foods that are gentle on the body, including fruits and veggies while cutting out meat. People with type B blood should avoid common grains like corn and wheat, as well as lentils, tomatoes, chicken, peanuts, and sesame seeds. People with the O blood type should munch on meats and vegetables and limit grains, beans, and dairy. Finally, AB blood types should eat tofu, dairy, and seafood, while avoiding caffeine, alcohol, and some meats.

In addition to overhauling your food, the diet also makes several recommendations for vitamins and supplements, depending on blood type. D'Adamo says that the adjustments recommended are based on the diets followed by our ancestors, and he claims that each blood type evolved with different nutritional needs (per Healthline). To date, 10 million people are said to have tried the diet — but some experts disagree with the hype.

Since the blood type diet debuted in 1996, it has gained the attention of fans trying to improve their health — as well as skeptical doctors and researchers. In one study published in the American Journal of Clinical Nutrition, researchers concluded that there is no evidence to support the blood type diet. Another research article published in PLOS One suggested that any benefits related to the diet have nothing to do with blood type, shattering Dr. Peter J. D'Adamo's claims that blood type should be at the center of dieting and meal planning.

Moreover, Harvard Health Publishing warns that several factors must be taken into consideration when choosing a diet to follow. Diabetics and people with other health conditions are likely better off getting tailored advice from a doctor or dietician who will take their personal needs, beyond blood type, into account. Verywell Fit also argues that many doctors advise against the diet because it can be restrictive and requires supplements in place of nourishing food. Instead of following a limiting diet plan based on blood type theory, it may be more beneficial for overall health to consume a variety of healthy foods every day including whole grains, vegetables, fruits, beans, nuts, seeds, and lean protein.

Studies have debunked the blood type diet, so why do so many people continue to claim that it works? Celebrities like Hailey Bieber (per Women's Health Magazine) and Ellen DeGeneres have followed Dr. Peter J. D'Adamo's advice, and millions more have bought his book. And they might not be completely wrong in believing that it offers some health benefits.

A review of the diet by Healthline points out that the meal plans recommended for each blood type tend to focus on nutrient-rich whole foods, and switching to one of these plans would be an improvement for almost anyone who otherwise relies on processed, junky foods. However, the improvement likely has no correlation with blood typing.

Neal Barnard, MD, also spoke on The Exam Room Live Podcast about how the type A diet in particular, which is largely plant-based, has been shown to lead to weight loss and lower cholesterol levels. However, he explained that the type A diet showed benefits not only for people with type A blood but also for people with other blood types.

Depending on your previous eating habits and which specific blood type diet you try, there may be some merit to this trendy diet plan. But the final verdict, according to experts? Throw out the blood test, and load up on fruits and vegetables instead.