And yes, many people find they feel better and maintain their ideal weight when they eat the foods recommended for their specific blood type. However, there' s a. snag. The blood type diet is based on giving foods that were available when each blood type was most prevalent. For example, type O is associated with hunter-gatherer eating, and people with this blood type tend to do better on more meat protein, while As are essentially peasant farmers, doing better on grains. The trouble is that in the 21st century we have other factors to take into account, such as consuming antioxidants to protect us from the effects of pollution, or eating beans such as soya to stave off cancer. In the nutritional principles I lay out in The Optimum Nutrition Bible, I take account of these factors. So most people would be better off starting with these as the basics, and then using the blood type guidelines to ' fmetune' their diet.