Hi
@derry60 You are right, it is very complicated, but weight gain is the result of too much insulin (not too much glucose). Insulin is a fat carrying hormone. The excess circulating insulin comes
before T2 diabetes. It causes insulin resistance, fatty livers/pancreases, and weight gain. Then at some point later, higher blood sugars and then diabetes. Clearly there are other reasons for weight gain.
Naturally thin people have different sized fat cells in their bodies and somehow because of this they manage to escape subcutaneous fat developing, but do not escape insulin resistance and fatty livers/pancreases. Whether fat or thin or anywhere in between, high circulating insulin is the problem and is likely to lead to diabetes eventually - maybe years down the line. (This is only one of the causes of T2 of course!) It also is thought to be a cause of CVD, altzeimers, inflammatory diseases and so forth.
High insulin levels are caused by excess carbohydrate.