What Happens to Your Body When You Eat Fast Food on GLP-1s

Glucagon-like peptide-1 receptor agonists (GLP-1s) like Ozempic (semaglutide) help manage blood sugar levels and support weight loss, but they do so by slowing the rate at which your stomach empties. Fast foods that are highly processed and high in fat can sit in the digestive tract for longer, leading to uncomfortable and unwanted side effects when you eat them while taking GLP-1s.

1. You May Experience Heartburn

Heartburn may be more likely if you eat certain foods while taking GLP-1s. These medications delay gastric emptying, which creates the opportunity for acid reflux to occur.

Spicy, fried, fatty, or acidic foods are known to worsen symptoms of gastroesophageal reflux disease (GERD), like heartburn. Note that you might be especially likely to experience this symptom while eating fast foods on GLP-1s if you already have a history of GERD or related symptoms prior to taking this medication.

2. You Might Feel Queasy

Nausea and indigestion (or an upset stomach) can happen while taking GLP-1s if your diet consists of high-fat or greasy foods like fast food. Nausea is a commonly reported GLP-1 side effect in clinical trials.

These medications cause food to remain in your stomach for longer periods of time. As the food contents linger, symptoms like nausea and an upset stomach are more likely to occur as your digestive tract slowly absorbs the food.

3. You Could Experience Bloating

Sugary fast food and beverages may be to blame for increased bloating, upset stomach, and gassy symptoms on GLP-1s. These medications are meant to help regulate blood sugar levels and appetite—but consuming fast foods with excessive added sugar can have the opposite effect on blood sugar and digestion.

This may be particularly true if you’re consuming carbonated liquids, such as soft drinks or other sweet carbonated beverages, which are known to prompt bloating and gas.

4. You May Vomit

Vomiting is another common symptom that occurs on GLP-1 medications in somewhere between 5% to 20% of people. While this symptom is typically reported to resolve within the first week of taking the medication, it may persist if you continue to eat high-fat foods like fast food.

This side effect tends to happen as a result of prolonged nausea due to the delayed stomach emptying.

5. You Could Have Diarrhea

Diarrhea may occur in up to roughly a quarter of people taking GLP-1 medications, which could be exacerbated with the consumption of fatty or greasy foods. As GLP-1s slow the absorption of nutrients in the digestive tract, the presence of excess fatty foods in the stomach could trigger an overactive stool reflex—leading to diarrhea.

You may be more likely to experience diarrhea on GLP-1s while eating fast food if you’re not already consuming enough fiber to regulate bowel movements, or if you’re also taking the heartburn medication omeprazole.

6. Your Weight Loss Efforts May Be Stalled

In addition to common digestive side effects, the overall purpose of taking a GLP-1 medication may be stalled when you eat a diet high in fast food. Weight gain can occur when you regularly consume high-fat or sugary foods on these medications.

GLP-1s help reduce appetite but don’t affect the calories you do take in. For the best results, experts recommend not indulging in fast foods often and sticking to a balanced, nutritious diet.

Foods to Avoid on GLP-1s

To minimize the chances of experiencing adverse side effects, research suggests some foods to consider avoiding while taking GLP-1 medications, including:

• High-fat foods
• Fried or greasy foods
• Processed foods
• Spicy foods
• Acidic foods
• Sweets
• Dressings
• Canned foods
• Dairy products (especially if you have diarrhea)

Note that a healthcare provider can offer individualized dietary guidance if your’e taking a GLP-1 medication.

Foods to Include on GLP-1s

Foods that you may want to prioritize while taking a GLP-1 medication include:

• Low-fat foods
• Easy-to-digest (or bland) foods
• Water-rich foods
• Clear liquids
• Lean protein
• Whole grains
• Fiber
• Fruits and vegetables

Other Tips for Eating on GLP-1s

Here are some other lifestyle tips that experts recommend to support prioritizing a nutritious, balanced diet:

• Eat slowly and without distractions.
• Consume smaller portions more frequently.
• Try not to lie down immediately after eating.
• Stop eating when you’re full.
• Avoid using a straw while drinking.
• Limit eating too close to bedtime.
• Incorporate light exercise throughout the day—but not too soon after eating.