Fixed - If you have a reaction to the food after two years it is permanent. In other words, whenever you eat that food you will have a reaction. Delayed - delayed food reactions are generally mediated by the IgG antibodies. The reaction can occur days later and makes it difficult to diagnose. Allergens not flushed out of the body can turn into infections.
People can be addicted to allergy inducing foods.
People crave these foods and have a difficult time giving them up. Like any addiction, a person develops a tolerance level to the food. In order to achieve a high from that food, a person needs to consume more and more of it. Not only does the person feel better emotionally, but physically because eating the food stops some of the symptoms. These include fatigue, weakness, aches, pains, depression and a general hungover feeling.