There might also be a connection between weight gain and food intolerance or sensitivity. If you experienced unexplainable weight gain or are having a hard time losing weight despite your best efforts, food allergy may be to blame. Food allergies affect approximately three percent of the population, with food sensitivity and/or intolerance being far more common than actual allergies. Food allergies affect the immune system and cause a variety of different symptoms to occur. Therefore, there seem to be a connection between food allergies and weight gain.

Anaphylaxis : Threat to the Body