Posting this as a warning rather than a discussion, and I will edit the post if any of it turns out to be wrong.
I added fiber, made it noticeably worse, and only later worked out that I had added the bulk without adding the water.
One important qualification: fiber without adequate fluid is worse than no fiber. If intake is down, fluid is usually down too, and adding bulk to a dry system is how people end up in real trouble.
What to check: Soluble versus insoluble is the distinction that matters: psyllium and oat beta-glucan hold water; wheat bran adds bulk. On slowed transit with low intake, the first helps and the second often does not.
If your experience contradicts this, say so in the thread — I would rather be corrected here than have people act on a warning that does not hold.
Dr.GastroMayo said:I added fiber, made it noticeably worse, and only later worked out that I had added the bulk without adding the water.
That is correct as far as it goes, and here is where it stops going. 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.
Dr.GastroMayo said:I added fiber, made it noticeably worse, and only later worked out that I had added the bulk without adding the water.
Worth saying plainly that not all of this is benign. Severe constipation on delayed gastric emptying has produced obstruction and ileus cases, rarely but genuinely. Pain with vomiting and no bowel movement is not a fiber conversation.
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View ResultsThis one has a reasonably settled answer, so here it is. The escalation order that reflects the mechanism: water and salt first, then soluble fiber, then magnesium or an osmotic agent, then a stimulant only briefly and only if the osmotic has failed. Stimulants first is the commonest error and the one most likely to end in a cycle of dependence.
BethLabQueen said:The mechanism is slowed transit plus reduced intake, and that combination determines which interventions work.
Can confirm. Same sequence, different timescale.