I know there are two (or more) schools of thought on this but I think that we all have a threshold that our bodies simply refuse to go lower than and if we artificially try to force it to cooperate, other things kick in which could also have a negative affect. For example, my cholesterol level REFUSES to drop to this 'normal' magical level of 4 which I know through trial and very stressful error, to get it to do so I would have to take a drug...and I won't because my ratios are perfect. I do get that when a body is wonky in some way it can do strange things but having said that our body's are complex, clever and wonderful things, it can adjust & compensate. Do you think your health would be massively better if it dropped below 42? To me you seem very stable and surely that is a good thing, you are thin, you are low carb, you exercise, the only way you coud get it lower is by medication (by the sound of it) and would you really want to do this and render you vulnerable to other risks, to get it a few points lower?. You are doing a great job in my opinion. x