An allergy is mediated by IgE antibodies and creates an immediate reaction. A sensitivity is created by IgG antibodies and create a delayed response. While these general traits hold true, there are also times when IgG can amplify IgE reactions, and also some examples of if there is a very high level of IgG, it can have more of an immediate reaction too. They create independent reactions but can also influence each other. IgG is most typically a delayed reaction, but if high enough titers are present, it too can react within a few hours. The interplay between parts of the immune system demonstrates why it is best to look at multiple antibodies together.  

IgG reactions are both the cause and the result of gut-based permeability. One way we develop IgG reactions is when the gut becomes more compromised or permeable. This allows for larger molecules than normal to “leak” through the gut. These larger molecules look antigenic to the immune system. T cells become sensitized and begin to make an immune response or produce antibodies. However, this is not the only way one can become sensitive to foods. Improper immune queuing in the GI tract, specifically in cells called the Peyer’s patches, can also cause this too. 

Once an IgG reaction begins, it increases production of histamine and inflammation. This inflammation continues to damage the gut, thereby contributing to permeability. The best way to reduce gut-based inflammation, is to remove offending foods and work on healing the gut. 

Food sensitivities can be related to weight gain in that they will create more inflammation in the body. Inflammation will cause an increase in the hormone leptin, which in turn tells adipose tissue to store more fat. Inflammatory foods create and irritation that leads to weight gain.