Your first week on Wegovy or Mounjaro (plus week 2 and beyond)

What to expect on your weight loss journey with medication

In this guide

What to expect on weight loss medications

Starting your weight loss journey

Wegovy and Mounjaro are injectable weight loss medications that work by mimicking natural hormones in our bodies. They can aid weight loss because they slow digestion, help control food cravings and make us feel full more quickly.

If you're reading this guide, you probably know the basics already. If not, we recommend reading about SemaPen's Wegovy and Mounjaro programmes, as well as the possible side effects of the medications.

Are you ready to start taking Wegovy or Mounjaro? In this guide, we show you what to expect with each medication as your treatment continues.

However, you should keep in mind that this might not reflect your own experience. This is a typical weight loss journey, but it can't account for differences in diet, lifestyle and how our bodies work.

What to expect on Wegovy

Week one

Your first few weeks on Wegovy are a period of adjustment. You might feel some side effects as your body gets used to the medication – nausea is quite common. Most side effects are fairly mild but can still be unpleasant.

Don't be disheartened at this stage. Remember that your weight loss journey is a marathon – not a sprint. Many people find that the side effects get better with time, too.

The good news is that you should start feeling the effects of the medication almost straight away. When you eat, you should feel full more quickly. And you might feel a sensation of fullness even when you haven't eaten.

Wegovy weight loss in week one

You probably won't notice any weight loss at this stage. If you do, it won't be more than a few pounds. Keep at it – you're only just getting started.

Week two

Week two will feel quite similar to week one. You might continue to experience side effects and may notice a little weight loss – but nothing drastic. (Remember: marathon, not sprint!)

Another thing you might notice is that the effects of the medication wear off after five or six days. That's because you don't yet have enough of the active ingredient (semaglutide) in your body.

Week three

You're still adjusting – but that sensation of fullness will probably feel more consistent throughout the week. You may also lose a few more pounds, but you probably won't notice any physical changes just yet.

Week four

For many people, the initial side effects will have now worn off. By now, the semaglutide in your body has reached a steady level. You should feel fuller most of the time.

Wegovy weight loss after one month

It's unlikely you'll see much (if any) visible weight loss yet. Focus your efforts on maintaining a healthy diet and getting regular exercise. The visible results should soon come.

Months four and five

At this stage, you won't just see the results of your medication – you should feel them, too. You'll probably have more energy for daily activities – and you'll feel less tired because you'll sleep better.

If you've kept up with diet and exercise, you can expect to have lost about 10% of your body weight by the end of month five. Give yourself a pat on the back. You've earned it!

Month six and beyond

How are you finding the new you? By month six, you'll be on the highest dose of the medication. You should have lost around 15% of your body weight. And that weight loss should come with a raft of health benefits, including improvements in blood sugar, cholesterol and blood pressure.

Don't give up now, though. To maintain your weight loss, we recommend you keep taking Wegovy along with diet and exercise for at least 12 months.

What's different on Mounjaro?

Mounjaro works in a similar way to Wegovy. For many people, the Wegovy and Mounjaro weight loss journeys feel quite similar, too.

As with Wegovy, you may experience side effects – especially when you first start taking the medication or change to a higher dose. And like Wegovy, you should begin to see visible weight loss between months three and six.

Here are the main differences with Mounjaro:

You should expect to lose more weight: Mounjaro patients typically lose 21% of their body weight in total.¹ With Wegovy, it's 15%.²
You should lose weight faster: with Mounjaro, patients tend to reach their goals a little more quickly.
You may experience fewer side effects: in clinical trials, Mounjaro tended to produce fewer and less pronounced side effects than Wegovy.

However, it's worth noting that Mounjaro can produce side effects that don't tend to happen with Wegovy. This includes hair thinning (actually caused by rapid weight loss) and making the contraceptive pill work less effectively.

Mounjaro weight loss by week and month

Your first week on Mounjaro

With Mounjaro, your first week won't result in any weight loss – or, at least, nothing visible. As with Wegovy, this is a period of adjustment. Your body needs to get used to the medication before you see results.

Your first month on Mounjaro

It's a similar story with Mounjaro and Wegovy here, too. If you experience any Mounjaro weight loss in a month, it's unlikely to be more than a few pounds. Focus on diet, exercise and getting used to the medication.

Months two to five

This is where Mounjaro's weekly weight loss really starts to ramp up. By the end of month three, you should expect to lose around 10% of your body weight. By month five, you should have lost about 15%

Month six onwards

You've reached the maximum dose and should have lost approximately 21% of your starting weight. Your cholesterol and blood pressure levels have likely improved. You should also have lost a good amount of visceral fat – the kind of fat associated with diabetes and heart disease.