Incretins and the Evolution of the GI Tract - Mike Eades (AHS21)
Channel: AncestryFoundation
Date: 2021-08-25

A few decades ago researchers discovered the incretin effect when they compared the insulin response to equal amounts of glucose provided either via IV infusion or orally. Oral consumption of glucose generated a 50% to 70% greater insulin response as compared to IV glucose, a phenomenon called the incretin effect and now known to be driven by peptides (called incretins) released from the enteric cells in response to food intake. It has been shown that the majority of the insulin response to carbohydrate consumption is a function of the type of processing the particular carbohydrate has undergone. Unprocessed or lightly processed carbohydrate foods stimulate a much lower insulin response than do the same carbohydrate amount that has been highly processed. Although the incretin effect does occur with protein and fat consumption, it does so to a much smaller degree. The carbohydrate content of the current American diet has recently reached similar levels to that of the first measured America diet circa 1900, yet thanks to the incretin effect, the highly-processed carbohydrate content of the current America diet stimulates vastly more insulin than did the diet of a century ago. Since insulin is the major metabolic hormone stimulating fat storage, the excess insulin driven by the incretin effect, in turn driven by the highly processed nature of the current American diet, can help explain the obesity epidemic much better than simply the macronutrient composition. The incretin effect also explains how bariatric surgery reverses diabetes so quickly and why the GLP-1 (an incretin) agonists work as anti-hyperglycemic agents.

Two errata from Dr. Eades:
If you do watch it, here are a couple of things to look for. I screwed up in two places.
@14:59 I say I'm showing the area under the glucose curve, but I meant to say the insulin curve. Big difference, especially in the context of this talk.
@22:18 I say the six obese men lost their 25 pounds in six weeks, but it was over three weeks instead. Another big difference.