GLP-1 and GIP – How They Aid in Weight Loss

GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic peptide) are incretin hormones that play crucial roles in the regulation of blood sugar levels, particularly in response to food intake. Both hormones are released from the gut in response to the presence of food being ingested and they have several actions that contribute to glucose stability, or homeostasis. GLP-1 is primarily produced in the distal small intestine and colon and enhances glucose-dependent insulin release from pancreatic β-cells. GIP is also produced in the small intestine and one of its primary effects is that it acts directly on pancreatic islets to stimulate insulin secretion. Insulin is a hormone that helps cells take up glucose from the bloodstream, reducing blood sugar levels.

 

So how do they help with weight loss?

• GLP-1 (Glucagon-Like Peptide-1):

Stimulation of Insulin Release: GLP-1 enhances the secretion of insulin from pancreatic beta cells. Insulin is a hormone that helps cells take up glucose from the bloodstream, reducing blood sugar levels.

Inhibition of Glucagon Release: GLP-1 also inhibits the release of glucagon, another hormone produced by the pancreas. Glucagon raises blood sugar levels by promoting the release of glucose from the liver. Inhibiting glucagon can contribute to better blood sugar control.

Slowing Gastric Emptying: GLP-1 slows down the emptying of the stomach, leading to a feeling of fullness or satiety. This effect reduces the rate at which nutrients are absorbed, contributing to a prolonged sense of fullness after meals.

Central Nervous System Effects: GLP-1 receptors are also found in the central nervous system, particularly in the brain regions associated with appetite and food intake. Activating these receptors can reduce appetite and food intake.

• GIP (Glucose-Dependent Insulinotropic Peptide):

Insulin Release: GIP stimulates the release of insulin from the pancreas which helps in lowering blood sugar levels by promoting the uptake of glucose by cells.

Increased Glucagon Release: Unlike GLP-1, GIP increases the release of glucagon in a glucose dependent manner. There is an enhanced release of glucagon from the pancreas at lower glycemia, or blood sugar.

Promotion of lipogenesis in adipose tissue: GIP has been associated with promoting lipogenesis, which is the process of fat synthesis. This action suggests that GIP may have a role in fat storage in adipose tissue.

 

The combined effects of increased insulin release, reduced glucagon secretion, slower gastric emptying, and appetite suppression contribute to weight loss in individuals taking GLP-1/GIP medications. Wegovy® is a GLP-1 medication and Zepbound® is a GIP/GLP-1 medication; both are specifically branded for weight loss. In addition, Ozempic®, a GLP-1, and Mounjaro®, a GIP/GLP-1, can also be used “off label” for weight loss. All these medications are taken once a week as an injection.

Interested in learning more about these medications and how they may be able to help you on your weight loss journey? Talk to your clinician at Scottsdale Weight Loss Center and get started today!

 

References

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Seino Y, Fukushima M, Yabe D. GIP, and GLP-1, the two incretin hormones: Similarities and differences. J Diabetes Investig. 2010 Apr 22;1(1-2):8-23. doi: 10.1111/j.2040-1124.2010.00022.x. PMID: 24843404; PMCID: PMC4020673.

Sun EW, de Fontgalland D, Rabbitt P, Hollington P, Sposato L, Due SL, Wattchow DA, Rayner CK, Deane AM, Young RL, Keating DJ. Mechanisms Controlling Glucose-Induced GLP-1 Secretion in Human Small Intestine. Diabetes. 2017 Aug;66(8):2144-2149. doi: 10.2337/db17-0058. Epub 2017 Apr 6. PMID: 28385801; PMCID: PMC5860185.