Blood type diets were first popularized by Peter D’Adamo in 1996, in his best selling book, Eat Right 4 Your Type.The basic principle behind his dietary idea is that ABO blood type is the most important factor in determining a diet. He found separate diets for people with one of the four most common blood types (A, B, O or AB). The theory behind this concept is that the ABO blood type should match the dietary habits of our ancestors and people with different blood types process food differently. Each blood type diet includes 16 food groups which are divided into three categories: 1. Highly beneficial 2. Neutral 3. AvoidWhat D'Adamo recommends for each type:1. Type O blood: A high-protein diet. 2. Type A blood: A meat-free diet based on fruits and vegetables, beans and legumes, and whole grains -- ideally, organic and fresh, . 3. Type B blood: Avoid corn, wheat, buckwheat, lentils, tomatoes, peanuts, and sesame seeds. He encourages eating chicken, green vegetables, eggs, certain meats, and low-fat dairy. 4. Type AB blood: Foods to focus on include tofu, seafood, dairy, and green vegetables.According to the theory, people following a blood type diet can improve health and decrease risk of chronic illness such as cardiovascular diseases. And, if you eat food other than the food which is meant for you according to your blood type, you may experience many health problems, including slow metabolism, allergies, asthma, cancer, heart disease and chronic fatigue."Based on the data from research by El-Sohemy, there is no evidence found to support whether Blood Type Diet works or not. The person’s response to any diet has nothing to do with their blood type." In 2013, a comprehensive review published in the American Journal of Clinical Nutrition found no evidence to support the 'blood-type' diet.There's no doubt that you would lose weight on this plan, as it's fairly low on calories. But the concern is about the healthy fibre and disease-protectiving antioxidants from fruits and vegetables that you would be missing out on.Rather than opting for a blood type diet you should focus on developing healthy eating and exercise habits that you can follow for a lifetime. Healthy, balanced meals will help you achieve healthy weight loss. You will also get all essential nutrients and be protected from most health disorders.