Semaglutide

WHAT IT DOES

Semaglutide is a long-acting analogue of glucagon-like peptide-1, a gut hormone released after eating. It binds GLP-1 receptors in the pancreas, the gut, and the hypothalamic appetite circuits. The dominant clinical effect is on intake, not absorption: in a 20-week double-blind trial of 72 adults, semaglutide at the trial dose of 2.4 mg weekly reduced ad libitum energy intake by 35 percent (1,736 versus 2,676 kJ) and improved measured hunger, fullness, satiety, and food craving scores (Friedrichsen 2021, PMID: 33269530).

The gastric emptying picture is more nuanced than the popular account. In that same trial, paracetamol AUC over 5 hours after a standardized meal rose 8 percent versus placebo (p=0.005), but the difference was no longer significant after correcting for week-20 body weight (p=0.12), and the authors concluded there was no evidence of delayed gastric emptying at week 20 by that indirect method. Yet gastric ultrasonography in real patients tells a different story: 56 percent had increased residual gastric content after standard fasting versus 19 percent of non-users (Sen 2024, PMID: 38446466). The practical reading is that transit effects are real, variable between people, and strongest in the days after an injection and during dose escalation.

This matters for supplements in two ways. First, whatever slows or scrambles gastric transit changes when an oral capsule dissolves and where it lands, which is the entire basis of the timing guidance below. Second, and more importantly, the reason people on semaglutide develop nutrient gaps is not malabsorption. It is that they eat 35 percent less food and the food they do eat is not automatically 35 percent more nutrient dense. Total energy falls, so total micronutrients and total protein fall with it unless something deliberate happens.

SAFETY PROFILE

Critical Interactions (Do Not Combine Without Medical Supervision)

Moderate Interactions (Monitor Closely)

Theoretical/Low-Risk Interactions