True or False? Adding Fat to A Meal Will Ameliorate the Insulin Response

True or False? Adding Fat to A Carby Meal Lowers Insulin Response - SuppVersity: Nutrition and Exercise Science for Everyone

False. When you are browsing the Internet it is easy to get the impression that what is wrong or right is not determined by scientific evidence, but by the number of people who repeat it in their blogs, on their facebook walls and in their bulletin board contributions. The common "wisdom" that it would be a good idea to add some fat to a meal to reduce the insulin spike it will give you is one of those paradigms that remain intrinsically flawed no matter how often they are repeated.
Figure 1: Althoug the glucose AUC drops after the addition of fat (slowed absorption of glucose from the intestine), the amount of insulin (2ndary axis) that is needed to stash the glucose away is 8.5x higher (on a per unit base; cf. violet bar) and the absolute insulin response does not decrease at all in lean healthy men and women (Collier. 1983)
If you do take a look at what actually happens, when you add fat to a meal, it is yet not difficult to understand how that myth came about. Just like people don't understand that the GI of a certain carbohydrate source doesn't tell you much about it's effect on insulin, the fact that the addition of fat ameliorates the postprandial spike in glucose gets misinterpreted as "fatty meals are less insulinogenic than low fat meals". In fact, the addition of 50g of butter on top of the 50g of carbohydrates the 8 lean, weight stable men and women (N=4, each) consumed in form of potatoes, did not have any effect on the post-prandial insulin release at all.

GIP Or Not GIP - That is the Question: "Fat intake, in addition to ingestion of carbohydrate, stimulates GIP release. Therefore, during a mixed meal GIP might act to promote the storage of both triglyceride and glucose indirectly via the release of insulin." (Kieffer. 2003)
The amount of the fat storage peptide GIP (learn more), on the . Therefore, Collier and O'Dea are 100% right, when they state in the conclusion of their 1983 paper that...
"despite the apparent improvement in glucose tolerance when carbohydrate is ingested together with fat, the accompanying potentiation of insulin secretion could form the basis of long-term changes in insulin sensitivity which accompany alterations in dietary fat intake." (Collier. 1983)
You may want to remember that, whenever you feel inclined to add a ton of bacon on top of your sweet potatoes in the false believe that this would "mitigate" the effects of the carb-laden tubers the insulin response.

This obviously does not change the fact that having some fat in a meal does have the added benefit of increasing GLP-1 and PYY levels and thus contributing to a longer satiety effect (eg. Knut. 2008)