GLP-1 constipation: a dietitian's practical guide.

Aim for 25–35g of fiber daily, with a mix of types. The average American eats about 15g — so most people need to roughly double their intake. On a GLP-1, that has to be done thoughtfully because appetite is low and fullness comes fast. The goal is fiber-dense foods at every meal, not big volumes of low-density food.

At least 64–80 oz (2–2.5L) per day, more if you're sweating or in a hot climate. Fiber without fluid is worse than fiber alone — it can actually worsen constipation by making stool drier and harder to pass.

On a GLP-1 the trick is that large volumes of fluid can amplify the early-fullness signal and worsen nausea. So sip steadily throughout the day, between meals rather than during, and use a marked water bottle so you can see your progress. Plain water, sparkling water, herbal tea and broth all count.

Yes — magnesium has well-established evidence for constipation and is generally safe at moderate doses. Magnesium citrate and magnesium oxide are the most laxative forms; magnesium glycinate is gentler and often used as a nightly maintenance dose. A reasonable starting dose is 200–400mg of magnesium citrate or glycinate at night, increasing gradually if needed.

Magnesium isn't a substitute for fiber and fluid — those have to come first. But if you've covered the basics for a week and still aren't moving, magnesium is the next lever before reaching for stimulant laxatives. Talk to your prescriber first if you have kidney disease or take medications affected by magnesium.

Movement stimulates motility throughout the GI tract. Twenty to thirty minutes of walking a day is enough to make a measurable difference for most people, and it has the added benefit of supporting muscle preservation — the other major nutrition concern on GLP-1s. You don't need a workout. A walk after lunch and another after dinner is plenty.

If you've consistently covered all four levers for 7–10 days and still aren't going at least every 2–3 days, that's a call to your prescriber. Options from there include MiraLAX (PEG 3350) as a safe, non-stimulant daily option, short courses of stimulant laxatives, or in rare cases a dose adjustment of the GLP-1 itself. None of these should be your first move — but none of them are failures either. Constipation is something to actively manage on a GLP-1, not something to push through.