Foods to avoid when on weight loss drugs and why it matters

Tanya Reynard | Last update: 6th August 2025

Why what you avoid matters

These medications reduce your appetite, which means every bite needs to count. It’s not about cutting everything “bad”, it’s about choosing foods that give your body the nutrients it needs to function well, especially when you’re eating less.

Certain foods can:

• Trigger nausea or digestive issues
• Spike and crash your blood sugar
• Fill you up without giving you real nutrients

1. Greasy and fried foods

Think: chips, fried chicken, fast food, battered fish, anything dripping in oil.

Why avoid: These can cause or worsen nausea, bloating, diarrhoea or indigestion are all common side effects when starting GLP-1s.

“I had a portion of fries early on in treatment and felt rough for hours. Not worth it.” – SlimrChat user

2. Sugary treats and processed snacks

Think: cakes, biscuits, sweets, pastries, cereal bars, ice cream.

Why avoid: Sugar causes blood sugar spikes and dips, which can make you feel dizzy, tired and hungry again too soon. It also offers little nutrition.

Pro tip: If you’re craving sweet, try fruit or yoghurt with berries.

3. Alcohol (especially on an empty stomach)

Think: wine, beer, spirits, cocktails even in small amounts.

Why avoid: Alcohol can irritate your stomach, worsen nausea and increase the risk of low blood sugar. Plus, it’s high in empty calories and can slow fat burning.

Some people find their tolerance drops significantly on GLP-1s.

“One glass of wine hit me like three used to. I’ve had to rethink my habits.” SlimrChat member

4. Carbonated drinks (especially sugary ones)

Think: fizzy drinks, sparkling juice, energy drinks, soda water.

Why avoid: These can cause bloating, discomfort and burping, especially if your stomach empties more slowly on medication.

Even zero-calorie versions may still trigger cravings or reflux for some people.

5. High-fat dairy and creamy sauces

Think: cheese-heavy meals, cream sauces, whole milk, full-fat ice cream.

Why avoid: Like greasy foods, these can increase the risk of nausea and indigestion. Some people also become more sensitive to rich foods while on treatment.

“Creamy foods started making me queasy, even my favourite mac and cheese.”  SlimrChat community post

6. Highly processed carbs

Think: white bread, white rice, instant noodles, crackers, many breakfast cereals.

Why avoid: These break down quickly into sugar, giving you a blood sugar spike with no real staying power. You’ll feel hungry again fast and miss out on essential fibre.

Choose wholegrains when possible and your energy levels (and digestion) will thank you.

7. Large meals or eating too fast

Why avoid: These medications slow stomach emptying. Eating big meals too fast can cause pain, nausea, and make you feel overly full for hours.

Try this instead:

• Eat smaller meals more slowly
• Stop when you feel full (even if food is left on the plate)
• Chew thoroughly and pause between bites

What it’s really about: making space for what matters

Avoiding these foods isn’t about punishmen, it’s about making room for the ones that help you:

• Feel energised and strong
• Keep hunger and cravings under control
• Support your body with nutrients, protein and hydration

“I learned to swap the junk for food that actually helped me feel good. The difference was massive.”

The NHS Eat Well Guide shows how much of what we eat overall should come from each food group to achieve a healthy, balanced diet.

As your appetite is reduced there are two key food groups to prioritise – read our articles on Fibre and Protein

Final thoughts

These weight loss drugs give you a head start, but what you eat still matters. By avoiding the foods that slow you down or make you feel worse, you give yourself the best chance of hitting your goals and feeling your best.

And remember: the SlimrChat community is here to support your choices, not judge them.