My first 4 weeks on Mounjaro: What to expect and how to prep for success
Peter Paumgardhen | Last update: 21st December 2025
Thinking of starting weight loss drugs in the New Year? You’re not alone. January is the most common time people look to make a real change – and for many, that now includes GLP-1 medications like Mounjaro and Wegovy.
But what can you really expect in those first four weeks? How should you prepare your body – and your mindset – so you get the best start?
We’ve pulled together what to expect in your first month, real insights from users in our Your Jab Life interviews, and some of the most helpful SlimrChat guides to help you plan, pace yourself, and stay on track.
Before you start: Get your head in the game
GLP-1s like Mounjaro can be life-changing – but they’re not magic. They give you an opportunity to reset your habits. What you do with that opportunity matters if you want to achieve long-term weight loss.
Before your first injection:
- Understand how it works: Read How GLP-1 weight loss drugs work
- Check the prescription process: See How do I get a weight loss drug prescription?
- Prep your mindset: Set realistic goals for body, mind and health
“I spent the first two weeks fighting it. I didn’t believe the appetite suppression was real — I kept expecting to feel hungry.” Moot, SlimrChat member
Week-by-week: What to expect on Mounjaro
Week 1: Start slow and listen to your body
- You’ll usually begin on a low dose (2.5mg)
- Appetite may reduce a bit, or not at all – that’s normal
- You might feel tired or foggy for the first few days
- Mild nausea or bloating is common – stick to bland, protein-rich meals
“The tiredness hit me like a truck, but it passed quickly. I just needed to rest more and stop expecting to feel ‘normal’ on day 1.” GreenmanZ, SlimrChat member.
Read: Feeling tired on weight loss drugs? It might be your diet
Week 2: Side effects or smooth sailing?
- For many, side effects appear around now – constipation, nausea or indigestion
- Energy may improve as your body adjusts
- Food ‘noise’ may start to reduce (less obsessing over food)
- Water becomes your best friend – sip it all day
“I didn’t realise how loud food had been in my head until it went quiet. It was unsettling, but kind of liberating too.” 00heaven, SlimrChat member.
Read: Side effects and how to deal with them
Week 3: Appetite suppression kicks in
- You may feel full faster or less interested in food
- You might forget meals – not ideal! Try to eat enough protein
- Weight loss may start (1–3 kg is common by now)
- Emotions may fluctuate – be kind to yourself
“The scale started moving, but more than that, I just felt lighter. Less bloated. Less controlled by cravings.” CathyYorks, SlimrChat member.
Read: Your Protein Manifesto
Week 4: Find your rhythm
- Most people settle into a pattern of smaller meals, more mindful eating
- Sleep and mood may improve – but keep managing stress
- This is a great week to build habits for movement and prep
“I finally felt like I had a routine. I wasn’t trying to ‘be good’, I was just eating when I needed to and walking when I could.” Julia1976, SlimrChat member.
Try: Week 1 of the Mounjaro Reset Plan
How to mentally prepare for the first month
The most successful users often:
- Reframe their goal: it’s not just about weight, it’s about freedom from food obsession
- Accept the weirdness: food might taste different, social eating might feel awkward at first
- Expect to feel emotional: grief, relief, disbelief, guilt – it all comes up
“I cried when I realised I didn’t need to clear my plate. I wasn’t trying to – I was just full.” EmmaG, SlimrChat member
5 things to do now before you start
- Get your prescription lined up
Check this guide - Prep your kitchen
Stock protein go-tos: Greek yoghurt, tuna, eggs, frozen chicken, Skyr, soup. - Choose your support system
Join the SlimrChat forum or talk to trusted friends. - Track your baseline
Weight, sleep, hunger, mood. Start a simple daily log. - Plan a gentle movement habit
Walk 10 minutes daily. Nothing fancy. Just move.
Final word from SlimrChat
Your first month on Mounjaro is about adjusting, not perfecting.
You’re not going to do everything right and you don’t have to. The biggest win is staying consistent, even when it feels strange or slow.
“This isn’t a magic fix. It’s a reset button. But it only works if you actually reset.” Robert, SlimrChat member.
You’ve got this. We’re here with you.