Indeed, Becky, you are correct. (But that could still be the weight loss, not the low-fat aspect.)
Bottom line seems to me to be that a fresh food diet (avoid processed food) that ignores the government's push for more carbs (60%, really?!) and has a wide variety of nutrients is probably the best option until we get a definitive study. Add some exercise. Don't go overboard with any of it.
One of the suggestions I've heard is intermittent fasting. Here's a link to the Genesis 2-Day Diet materials I collected in my Dropbox back when I was researching diet:
https://www.dropbox.com/sh/entsqdfk2...bRNsNN3Fa?dl=0
This is the study the Genesis Diet is based on:
http://journals.cambridge.org/action...07114513000792
The study PDF is also in the Dropbox folder I linked to.
This is the Genesis page at University Hospital at South Manchester:
http://www.uhsm.nhs.uk/research/Pages/Genesis.aspx
At the bottom of the page, you'll find additional links.
The answer to your first question, Spitfire, is "there's no way to know." The answer to your second question is "lab tests."
Here's a study (includes list of what they measured):
http://www.ncbi.nlm.nih.gov/pubmed/19116382
I'm in the Metformin study. Given the amount of money invested in the study (to fund 300+ study sites), I can only assume IGF1 is prevalent.