Ozempic, Wegovy or Mounjaro causing bloating or constipation? What to know about GLP-1 gut side effects

Bowl of protein-rich Greek yoghurt with blueberries and figs, high protein meal for managing GLP-1 gut side effects

Started Ozempic, Wegovy or Mounjaro and suddenly your gut has opinions? Bloating after small meals. Constipation that won’t budge. Nausea that shows up mid-afternoon. Reflux out of nowhere.

While GLP-1 weight loss medications help manage insulin resistance, weight and metabolic health, they also change how your digestive system works. And that’s where a lot of these gut symptoms come from.

So, here’s what’s actually happening and diet tips to help reduce digestive issues.

Why Do Ozempic, Wegovy and Mounjaro affect Digestion?

All three medications (Ozempic, Wegovy and Mounjaro) work by mimicking or enhancing GLP-1 (glucagon-like peptide-1), a hormone involved in appetite regulation and blood sugar control.

One of GLP-1’s main jobs is to slow gastric emptying. In simple terms, food stays in your stomach longer.

This helps with:

  • Feeling fuller for longer

  • Reducing appetite

  • Supporting blood sugar stability

But, slower digestion can also mean:

Do you have diagnosed IBS while also taking a GLP-1 weight loss medication? Get specialised support from our IBS expert Dietitians

MEET OUR EXPERT IBS DIETITIANS

Common Gut Symptoms on GLP-1 Weight Loss Medications

While everyone’s experience is different, the most common digestive side effects we see with patients include:

1. Constipation

Slower gut movement plus reduced volume of food actually eaten each day can mean fewer bowel movements. Constipation is one of the most common reported side effects of weight loss medications, especially in the first few weeks or after dose increases.

2. Bloating after eating

Because food sits in the stomach longer, larger meals suddenly feel uncomfortable and bloating happens.

3. Nausea

Especially early on or after dose increases. This is one of the most common effects alongside constipation and makes eating a big challenge! The downside? Not eating and having an empty stomach further worsens nausea.

4. Reflux or heartburn

Slower digestion increases pressure in the stomach, which contributes to reflux symptoms.

Practical nutrition tips to reduce digestive symptoms from weight loss medications

First things first: you don’t need a restrictive diet. You don’t need to cut out entire food groups. And you definitely don’t need to panic-Google elimination plans.

But, you do need to adjust how you eat. Because when digestion slows, meal size, composition and timing matter more than before.

The key diet changes you need to make include:

  • Adjusting how much food volume you have at each meal or snack

  • Balancing appropriate amounts of protein, carbohydrates and fats (instead of heavily skewing towards just one!)

  • Drinking enough fluid and separating fluids from main meals (here’s our top tips)

  • Modifying the types of fibre you eat and focusing on “soft” soluble fibre

  • Avoiding long gaps between meals

For example, large, high-fat meals can feel significantly heavier when the digestive system is slowed under a weight loss medication. But that doesn’t mean fat is “bad”, it just means the amount of fat needs to be balanced with other macronutrients.

Similarly, fibre can help constipation but increasing it too quickly on GLP-1 medications can worsen bloating. It’s rarely about “more fibre”. It’s about the right type and pacing for your body.

These are highly individual adjustments. And, they are often the difference between staying on the medication comfortably or feeling like you need to stop because digestion is miserable.

Final Thoughts: It’s Not “Just Side Effects”

If you’re experiencing constipation, bloating or nausea on Ozempic, Wegovy or Mounjaro this is common and expected. But while GLP-1 medications are useful medications for insulin resistance and metabolic health, they disrupt digestive function. And, this needs personalised evidence-based nutrition support to avoid ongoing gut discomfort and missing out on getting in enough important nutrients for optimal health.

At The Lifestyle Dietitian, we work with patients navigating GLP-1 weight loss medications and digestive side effects in a way that’s practical, non-restrictive and tailored to your body. If your gut has become an unexpected plot twist in your weight loss medication journey, we’re here to help you make sense of it.

Book an appointment with our team to get personalised nutrition guidance that supports both your health, your digestion and your relationship with food

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Frequently Asked Questions About GLP-1 Medications and Gut Symptoms

Do Ozempic, Wegovy and Mounjaro cause constipation?

Yes, constipation is one of the most common side effects of GLP-1 medications. These medications slow stomach emptying and gut movement, which can lead to harder stools or going less frequently. For some people it settles. For others, it needs active management. The key isn’t extreme fibre loading! It’s a more strategic, individualised approach that involves fibre modifcation, fluids, meal timing, toilet routines and osmotic laxative use in some cases (under a doctor’s guidance).

Why do GLP-1 medications cause bloating?

GLP-1 medications slow how quickly food moves through your digestive system. When food sits in the stomach longer, it can increase feelings of fullness, pressure or bloating. The goal is adjusting your eating pattern to reduce bloating while still meeting your nutrition needs.

Should I increase fibre if I’m constipated on Ozempic or Mounjaro

Sometimes yes, but not aggressively. Adding large amounts of fibre too quickly can actually worsen constipation, bloating and discomfort. What matters more is the type of fibre, the timing, your fluid intake and your overall meal structure. This is where tailored advice makes a big difference.

What should I eat while on GLP-1 medication for insulin resistance?

There isn’t one “GLP-1 diet.” Our previous blog here outlines the best way of eating to support:

  • Stable blood sugars

  • Adequate protein

  • Gentle fibre

  • Digestive comfort

  • Muscle preservation

Because appetite is often reduced, what you eat matters more than ever. Undereating or unintentionally missing key nutrients can backfire long term.

Will the gut side effects go away?

For many people, symptoms improve after the first few weeks as the body adjusts. For others, bloating, nausea, reflux or constipation persist, especially as doses increase. You don’t need to just tolerate it. Adjustments to how and when you eat can make a meaningful difference.

Can a dietitian help with GLP-1 side effects?

Absolutely! GLP-1 medications change appetite, digestion, food tolerance and your ability to eat enough nutrients for health. Having structured, practical support will help you:

  • Reduce bloating and constipation

  • Protect muscle mass

  • Meet protein targets

  • Avoid falling into unintentional under-fueling

We work with clients on Ozempic, Wegovy and Mounjaro every week in a way that’s supportive, non-restrictive and sustainable.

HUNGRY FOR MORE? CHECK OUT OUR LIBRARY OF ARTICLES AND RECIPES WRITTEN BY OUR DIETITIANS:

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