GAPS Diet was first described in 2004 in my book Gut And Psychology Syndrome. Since then it has become known all over the world, helping children and adults to recover from very serious health problems. During those years the diet has been evolving to suite more and more complex patients, and the full spectrum of the GAPS Diet has emerged. Some people do well with following the Full GAPS Diet, which is the easiest to implement and is very suitable for following as a permanent lifestyle. Many people have to go through the GAPS Introduction Diet, which is more difficult to follow, but it achieves deeper healing of the gut and the rest of the body. People with severe digestive problems, severe mental illness, and physical conditions found great help following the No-Plant GAPS Diet for a while. At the most severe end, patients with cancer, multiple sclerosis, Lyme disease, and other very serious health problems found the GAPS Ketogenic Diet to be the most appropriate approach. Then there are people who need to eat more plant matter to feel well; these people enjoy the More-Plant GAPS Diet.
( by Dr. Natasha Campbell-McBride, from her website, https://www.gaps.me/)
Later Dr. Natasha realized that many physiology syndrome or physiological health issues are also caused by gut dysbiosis which is described in her first book, Gut And Psychology Syndrome. And she wrote a book, Gut And Physiology Syndrome.
I suggest you read both books. So, you gain a better understanding of what has been happening to your health.