Peter is following Dr. K's diet. And Dr. K doesn't want people in ketosis but as Peter says his reasons are weird and don't seem well grounded in anything real. So he looked into it himself to see if there was anything really not so good about it.

I think dieting in general causes T4->T3 conversion to slow down. The not-low-carb Calorie restriction folks have already documented this along with the news that having a little lower T3 is associated with a longer life span.

Of course low calorie dieters are in ketosis too. The definition is you're burning fat rather than glucose, right? We run into problems when the norm was established by people who are burning through the enormous amounts of glucose that people eat nowadays with the metabolic issues that comes with that.

I guess I'd be interested in finding the last of the real HG's and studying their blood! Maybe they're the true normal.