Gastric emptying

Gastric emptying is simply how quickly food leaves your stomach and moves into the small intestine. Every GLP-1 medication slows it down — the Wegovy, Zepbound, Saxenda and Foundayo labels all say so in plain language. This is not a side effect that slipped through; it is part of how the drugs work.

Slower emptying means food sits in your stomach longer, so you feel full sooner and stay full between meals. It also explains most of what people complain about in the first months: nausea, early fullness, burping, reflux, bloating and constipation. The same mechanism produces the benefit and the burden.

One detail is easy to miss and genuinely useful. The Zepbound label notes that the delay in gastric emptying is largest after the first dose and diminishes over time. That is the pharmacological basis for the advice people hear anecdotally — that the worst nausea usually comes right after starting or right after a dose increase, and then eases. It is also why pausing at your current dose rather than pushing upward is a legitimate strategy, not giving up.

The part that has real safety consequences is anesthesia. All of these labels now carry a warning about pulmonary aspiration during general anesthesia or deep sedation, because a stomach that should be empty after an overnight fast may not be. A 2025 study of 598 outpatient upper endoscopies found roughly four times the odds of solid food remaining in the stomach among GLP-1 users, with more procedures aborted — though no aspiration cases occurred. Our pre-op stop-date calendar and anesthesia guidance summary cover the planning.

Tell every clinician who might sedate you — surgeon, gastroenterologist, dentist, fertility clinic — that you are on a GLP-1, and ask how far in advance they want it held. See also GLP-1-induced gastroparesis.