Reference
GLP-1
**GLP-1** (glucagon-like peptide-1) is an incretin hormone secreted by enteroendocrine L-cells in the intestine after a meal that increases satiety, slows gastric emptying, and stimulates insulin secretion. It is one of the body's primary signals that food has arrived, and it has become widely known as the target of a class of weight-management and diabetes medications.
How GLP-1 works
When nutrients reach the small intestine, L-cells release GLP-1 into circulation. The hormone acts on the pancreas to increase glucose-dependent insulin release, on the stomach to slow the rate at which food empties, and on the brain’s appetite centers to reduce the drive to keep eating. The combined effect is lower post-meal blood glucose and a longer-lasting sense of fullness.
A randomized controlled trial found that a combined infusion of GLP-1, oxyntomodulin, and peptide YY over four weeks significantly reduced body weight by 4.4 kg and improved glycemia in individuals with obesity and prediabetes or type 2 diabetes (Diabetes Care, PMID:31177183). GLP-1 rarely acts alone; it operates alongside related gut hormones such as peptide YY, which shares 18 of its 36 amino acid positions with pancreatic peptide.
How dietary protein stimulates GLP-1
Among the three macronutrients, protein is a strong stimulus for satiety hormones. Protein increases satiety and reduces subsequent energy intake more than carbohydrate or fat, an effect mediated partly by diet-induced thermogenesis and hormonal responses including GLP-1 (PMID:18469287). High-protein meals also raise satiety and thermogenesis more than standard-protein meals (Journal of the American College of Nutrition, PMID:15466943).
This mechanism explains why protein intake matters to people using GLP-1 medications, which suppress appetite and can make adequate protein intake harder to reach. A 2025 market survey reported that 74% of GLP-1 users sought high-protein or protein-fortified products (Food Business News). Maintaining protein intake on a reduced-appetite regimen is covered in our guide to protein for weight loss.
GLP-1 and potato protein
Different proteins drive the post-meal glycemic and insulin response to different degrees. In an acute crossover study of healthy males, whey protein produced a larger insulin and glycemic response than potato or rice protein, while the plant-derived proteins had a lower insulinaemic response and better glucose maintenance; there was no significant difference in appetite between the proteins (Nutrients, PMID:34201703). Potato protein remains a single-ingredient, allergen-free option for those who cannot tolerate dairy. The practical priority for appetite-suppressed eaters is meeting total daily protein, regardless of which complete protein delivers it.
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