Dr berg DC has seeveral videos on utube about body types. Not the old system but one based on where the fat tends to accumulate. THEre ae 4 types.

He addresses the different dietary needs of each type based on the physiologgy that drives each.

https://www.youtube.com/watch?v=s54ioy8f7ek
https://www.youtube.com/watch?v=5NPVnXixQ8c
https://www.youtube.com/watch?v=xvOwfkg9p2o

These may help you find the underlying issue and the solution.

YOu have done so well. Hope you find an answer very soon.