How can dietitians manage GI side effects from GLP1s?

This is part two in my GLP-1s for weight loss series. The other posts in the series are:

• Part 1: What does every nutrition professional need to know about GLP-1s?
• Part 3: How can dietitians manage GI side effects from GLP-1s?
• Part 4: How and why do GLP-1s change dietary intake?

The Key Reference for this series of posts is: Mozaffarian, Dariush, et al. “Nutritional priorities to support GLP-1 therapy for obesity: a joint Advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and The Obesity Society.” Obesity Pillars (2025): 100181.

Given that GI side effects are common with GLP-1 therapy and can negatively impact nutritional status, strategies to help reduce symptoms are important to consider.

First and foremost to help prevent or manage GI symptoms is ensuring reasonable titration of GLP-1 therapy.  Gradual dose escalation improves tolerance to these medications. Clinical trials allowed up to 8 weeks before escalating the dose.

For specific symptom management, see the notes below.  In all cases, health care providers should ideally encourage people to reach early if they start to experience GI symptoms.

What should I recommend for patients who experience nausea and/or vomiting with GLP-1s?

• Recommend small, frequent meals
• Longer periods of time between meals may make nausea worse
• Avoid high fat or high fibre foods immediately after starting the medication or for a few days after each dose escalation
• Peppermint or ginger tea may help
• Anti-nausea medication may be helpful, however ones that are not associated with constipation (e.g. ondansetron) are preferred.
• Vomiting is most likely to occur after a large meal, which favours a small, frequent meal pattern over larger meals
• Encourage adequate hydration/prevent dehydration

What should I recommend for patients who experience constipation with GLP-1s?

Constipation is common with any type of weight loss, including weight loss induced by GLP-1 use.

• Ensure adequate fibre and fluids
• Avoid extended constipation episodes which can lead to reactive diarrhea
• Foods with lower viscosity, fewer calories, lower glycemic index and higher water content can improve gastric emptying
• Consider gradual introduction of foods with soluble and insoluble fibre.
• High protein or fat foods can slow gastric emptying and may make symptoms worse
  • Given the importance of high protein foods for weight loss, if these foods are minimized for constipation, ensure patients understand that this is a temporary intervention
• Consider magnesium supplements to encourage bowl regularity
• Fibre supplements or PEG can also be helpful
• Stool softeners can help prevent straining

What should I recommend for patients who experience diarrhea with GLP-1s?

• Avoid large or high fat meals
• With significant diarrhea consider fibre supplements to firm up the stool
• Anti-diarrheal medications can be considered for acute diarrhea
• Limit alcohol intake

Want to know more?

Up next in the series: Part 3: How and why do GLP-1s change dietary intake?

Find the other posts in the series here:

• Part 1: What does every nutrition professional need to know about GLP-1s?
• Part 4: What nutrition and lifestyle recommendations should be made for people taking GLP1 therapy?