There are serious structural problems with the MBTI. The best you can say about the MBTI is that it is very popular. As always you can find the critical information on google. Do a search on MBTI along with the terms bimodal, dichtomous dimensions. Because typologies do touch on peoples sense of self I don’t want to throw any of them on the garbage heap.
In dividing the somatotype triangle into MBTI areas you start with Fat (endomorphic) people in the Feeling zone. The Muscular/Athletic bodies share features of the Sensation zone with some of the peripheral body types (furthest from the middle). The Linear ectomorph is the thinking area. Finally the middle is the area of Intuition. When endomorphy, mesomorphy and ectomorphy are in close balance then the sensory system becomes very active in search of novelty to break the stalemate of balance and reorganize priorities.
With all of these diagrams it needs to be repeated that the lines are not like geographical boundaries. The main take away is that a person can easily appear as any type immediately adjacent to their real type. Quite often a person will take a job that is not ideal but tolerable and the effect will cause a minor adaptive change. However if someone has a body type of an ISFP and their test results indicate they are an ENTJ then it is likely that some maladjustment is involved.
The aim is to establish a bench mark and then observe in a reflective way how the test results could explain the drift away from the bench mark. The question that needs to be asked is what has moved in the hierarchy and how much. If the movement is large (opposite) compared to the bench mark somatotype, then a person needs to search their environment for events that could be a candidate for trauma.
Next: The Big 5 & Body Type