Lots of people are wondering whatever happened to the insulin index. I wondered too, so I asked Susanna Holt.

Dr. Holt developed the insulin index about a decade ago when she was working on her Ph.D. at Australia’s University of Sydney. Her work was exciting but preliminary.

She tested just 38 foods and found that their glycemic index and insulin index values were highly correlated. But there was a big exception.

Their most interesting finding was that “protein-rich foods and bakery...