Tuesday, April 19, 2011

Insulin & Weight/Fat Loss ~ The Long and the Short of It

In the comments of my recent post, On Cherry Picking & Debunking, my "Insulin Warring" partner Todd Becker posted a multi-point commentary.  I'll get to the rest over in the comments section in that post when I get a chance, but one of his points hit on something just a little different as it goes to the core of my issue with the insulin hypothesis. (And I'm reminded I'm long overdue for an installment on the IW exchange with Todd)

In any case, here was what I said:
G&K demonstrated absolutely no correlation between fasting insulin and weight change. Therefore fasting insulin is not a factor in determining weight loss.
Todd challenged:  
Your claim that there is "no correlation" between insulin levels and weight looks only at the instantaneous correlation. But fat loss may be a delayed response, as the Woodhouse paper I linked to you indicates. Figures 1 and 2 in G&K suggest that weight either dropped or plateau'd after a slight lag in the few cases where insulin levels approached 10 uU/ml. That the weight loss continued in some cases even after insulin levels begin to increase suggests that weight regain may be a delayed metabolic response.
And
The G&K protocol used "fasting insulin" as a surrogate for basal insulin. These are not the same thing. Fasting insulin was measured twice weekly at 7-8 a.m. after a 12 hour overnight "fast". But fat loss may depend on how much of the day insulin levels remain very low. Truly low basal insulin levels may take many weeks to establish.

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