carlos_SATX said:

The mechanism is slowed transit plus reduced intake, and that combination determines which interventions work.

Gastric emptying studies and constipation: semaglutide delays gastric emptying by ~40% at steady state, as measured by acetaminophen absorption testing and scintigraphy[1].

Clinically relevant implications:

• Explains early satiety and nausea
• Affects absorption of co-administered oral medications
• Creates aspiration risk for procedures under anesthesia
• Contributes to constipation via slowed GI transit

Importantly, the gastric emptying delay attenuates with continued use (tachyphylaxis), which correlates with the transient nature of GI side effects.

A narrower follow-up, since the general answer is now clear:

Whether fiber actually helps GLP-1 constipation or whether the evidence is borrowed from a different population?

hank_denver said:

Gastric emptying studies and constipation: semaglutide delays gastric emptying by ~40% at steady state, as measured by acetaminophen absorption…

Acid reflux and constipation: I developed GERD symptoms around week 3 that I'd never had before. The delayed gastric emptying means food and acid sit in your stomach longer.

Management that works for me: elevate head of bed 6 inches, don't eat within 3 hours of lying down, avoid trigger foods (tomato, citrus, spicy, chocolate), and famotidine 20mg at bedtime. Much better now.

OP back with an update, since a thread like this is useless without one.

Resolved: water and magnesium first, soluble fibre second, bran gone entirely. Two months of doing it in the wrong order and a week to undo.

DebRD_ATL said:

Acid reflux and constipation: I developed GERD symptoms around week 3 that I'd never had before.

Gastroparesis symptoms with constipation: the delayed gastric emptying from GLP-1 agonists can cause early satiety, bloating, and feeling "full" for hours after a small meal.

Tips: eat your protein FIRST (most important macro), then vegetables, then carbs last. Chew thoroughly — 20-30 chews per bite isn't excessive. Avoid carbonated beverages with meals. If symptoms are severe, your doctor may recommend a gastric emptying study.