Why Weight Loss Efforts Can Sometimes Lead to Constipation and Digestive Changes

Whether you’re cutting calories, swapping out processed foods or just eating less than your body is used to, constipation is one of the most common — and least talked about — side effects of any weight loss journey. The good news is that the same fixes doctors give to patients on prescription medications like Ozempic work just as well for anyone trying to slim down the natural way.

Why weight loss can leave you backed up

Constipation tends to creep in when your diet, hydration or routine shifts suddenly — and weight loss usually involves all three. “A lot of times, people get constipated because they’re dehydrated and if they’re dehydrated, they’re not able to process food,” registered dietitian Beth Czerwony told Cleveland Clinic. “So, not only is it important to have a well-balanced diet, but also to maintain your hydration status.”

For people taking semaglutide drugs like Ozempic, the problem is amplified because the medication slows gastric emptying, according to Mochi Health. Early clinical trials found roughly 3% to 5% of Ozempic users developed constipation, with newer estimates ranging from about 4% to 12%, per GoodRx. But you don’t need a prescription to run into the same plumbing problem. Eating less, eating differently or moving less can trigger it on its own.

Why fiber is the fix most people are missing

If there’s one number to memorize on any weight loss plan, it’s your daily fiber target. “The general recommendation for daily fiber intake is 38 grams for men and 25 grams for women,” Caroline Messer, M.D., an endocrinologist at Northwell Lenox Hill Hospital in New York City, told Health Central. “This can help alleviate problems like constipation, diarrhea, and nausea.”

Ramp up slowly, though. “If you don’t normally have fiber in your diet and then all of a sudden you start pushing fiber, you could end up with diarrhea just because your gut is working a little bit harder,” Czerwony said.

If you reach for a fiber supplement, hydration matters as much as the dose. Dr. William Yancy Jr., medical director of the Lifestyle and Weight Management Center at Duke Health, advises taking it with 8 ounces of fluid. “This can be increased by an ounce or two if stools remain hard, or decreased by that amount if they are too loose,” Yancy said. “People should avoid taking fiber capsules with just a sip of liquid. They need to be taken with a full glass.”

What to eat — and skip — when dieting

Dr. Michael Ruscio’s advice translates directly to anyone eating to lose weight, with or without medication. “Consider opting for whole, unprocessed foods over ultra-processed ones (the Mediterranean or Paleo meal plans are great examples),” he said, adding, “Experiment with adding more dietary fiber from fruits, vegetables, whole grains and beans.”

He also recommends incorporating “more foods that have high water content, like soups, fruits and vegetables” and avoiding concentrated sweets. Mochi Health singles out prunes as a low-cost first line of defense: “This sweet fruit has been shown to help with constipation. Try dried prunes or prune juice next time you feel backed up.”

Don’t underestimate movement either. “If you’re having any kind of mild nausea or constipation, go for an after-meal walk,” Czerwony said. “Doing so helps with digestion and helps relieve some of those symptoms.”

When to call a doctor

Most diet-related constipation eases up within weeks once your body adjusts. For semaglutide users specifically, “constipation from semaglutide (the active ingredient in Ozempic) is usually temporary and typically lasts about 6 weeks or 47 days,” according to Ro.

If symptoms drag on, get help. “Constipation may require stool softeners and laxatives,” Eduardo Grunvald, MD, director of obesity medicine at the Bariatric and Metabolic Institute at UC San Diego Health, told Health. “Nausea may require anti-nausea medications. Heartburn may require acid-blocking medications.”

“Every person is different, and it may be helpful for some and uncomfortable for others,” Grunvald said.

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This story was originally published June 2, 2026 at 1:17 PM.