I added fiber, made it noticeably worse, and only later worked out that I had added the bulk without adding the water.
The bit I cannot resolve on my own is whether fiber actually helps GLP-1 constipation or whether the evidence is borrowed from a different population.
Tell me what I have not thought of.
Short answer first, then the reasoning. Fiber trials in this population are thin, and most of what gets quoted is extrapolated from idiopathic constipation in people eating normally. The extrapolation is not unreasonable but it is an extrapolation, and it fails specifically for insoluble fiber at low intake — the case that comes up here most often.
kate.chem said:Fiber trials in this population are thin, and most of what gets quoted is extrapolated from idiopathic constipation in people eating normally.
Drug interaction alert relevant to constipation: if you take oral levothyroxine (Synthroid), GLP-1 agonists can reduce absorption due to delayed gastric emptying. My TSH drifted up after starting semaglutide.
Solution: take levothyroxine on an empty stomach, 60 minutes before any food, and have your TSH rechecked 6-8 weeks after starting or changing GLP-1 dose. My endo had to increase my Synthroid by 12.5mcg.
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View ResultsPeptideSynthNJ said:I added fiber, made it noticeably worse, and only later worked out that I had added the bulk without adding the water.
Same position here, arrived at the long way round. The mechanism is slowed transit plus reduced intake, and that combination determines which interventions work. Less food means less bulk, slower motility means more water reabsorbed, and the result is a smaller, drier, slower stool. Insoluble fiber adds bulk to a system that is already moving slowly, which is why it frequently makes things worse. Soluble fiber holds water and is the better first choice, and an osmotic agent works with the mechanism rather than against it.
I would rather be corrected than agreed with, if it comes to it.
Adding the clinical framing, because it changes how the question reads.
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.