Starting a weight loss pen is an exciting step — but what you eat in the first week can make a real difference to how well you tolerate the medication and how quickly you start seeing results.
GLP-1 medications slow digestion and reduce appetite, which means your stomach is working more slowly than usual. The right foods will keep you comfortable, nourished, and on track. The wrong ones can amplify nausea and fatigue, making those first days harder than they need to be.
Here's exactly what to eat — and what to avoid — in your first week.
Focus on Protein at Every Meal
Protein is your most important macronutrient when starting a weight loss pen. It helps preserve lean muscle as you lose fat, keeps you fuller for longer, and is easier on your digestive system than heavy carbohydrates or fats.
Good protein sources for week one:
- Eggs (scrambled, poached, or boiled)
- Grilled or baked chicken breast
- White fish (cod, tilapia, haddock)
- Greek yoghurt (plain, low sugar)
- Cottage cheese
- Tofu or tempeh
Aim for a source of protein at every meal, even if portions feel small. Your appetite will likely be reduced — that's the medication working.
Eat Smaller, More Frequent Meals
Because GLP-1 slows stomach emptying, large meals can cause uncomfortable fullness, bloating, or nausea — especially in week one. Rather than three big meals, try:
- 4–5 smaller meals or snacks spaced throughout the day
- Stopping eating when you feel 70–80% full (not stuffed)
- Eating slowly and chewing thoroughly
This simple shift reduces digestive discomfort significantly for most new users.
Choose Easy-to-Digest Carbohydrates
Heavy, starchy, or greasy carbs are harder for your slowed digestion to handle. Instead, opt for:
Good choices:
- White rice or plain rice cakes
- Cooked oats (porridge)
- Sweet potato (mashed or baked)
- Bananas and other soft fruits
- Plain crackers
Avoid for now:
- Large portions of bread or pasta
- Fried or greasy foods
- High-fibre raw vegetables in large quantities (broccoli, cabbage, beans)
- Spicy foods
You can reintroduce these gradually over the coming weeks as your body adjusts.
Stay on Top of Hydration
Nausea is more common when you're dehydrated. Aim for at least 2 litres of water per day. Herbal teas (ginger tea in particular) can also help settle the stomach.
Avoid:
- Sugary fizzy drinks
- Alcohol (especially in week one)
- Excessive caffeine on an empty stomach
A Sample Day 1 Meal Plan
Breakfast: Scrambled eggs with a slice of wholegrain toast and a glass of water
Mid-morning snack: Small bowl of Greek yoghurt with a handful of berries
Lunch: Grilled chicken breast with half a cup of white rice and steamed courgette
Afternoon snack: A banana and a small handful of almonds
Dinner: Baked white fish with mashed sweet potato and a side of wilted spinach
Evening: Ginger or chamomile herbal tea
Listen to Your Body
Everyone responds slightly differently in the first week. If certain foods cause discomfort, cut back and keep meals simple. The goal isn't perfection — it's building a sustainable foundation that makes your weight loss pen as effective as possible.
Want more guidance on combining nutrition with your weight loss pen? Read our full diet guide or explore our shop to get started.
This article is for informational purposes only. Please consult your healthcare provider or a registered dietitian for personalised nutrition advice.