Everything you Need to Know About Weight Loss Injections

Laura Eccleston
By Laura Eccleston

Laura graduated from the University of Sheffield with a degree in Biomedical Science. She has since undertaken various roles in the pharmaceutical industry before joining MediZen in 2019.


In February 2025 there were more than 600,000 searches for Mounjaro in the UK.

An increase of over 4000% compared to the previous month, showcasing the rising demand and interest in the revolutionary weight loss jab. With Mounjaro going viral on social media and the NHS announcing it will begin offering the weight loss drug to a select group of patients over the next few years, thousands are searching for more information.

We’ve gathered the important things we think you need to know if you’re exploring this weight loss method.

 

What is Mounjaro?
Mounjaro is a brand of weight loss injection that is self-administered weekly into the upper arm, stomach, or thigh. It works similarly to Wegovy (known as Ozempic in the US) and mimics two key hormones:
  • GLP-1: This hormone is released by the body after you’ve eaten, helping you to feel fuller which in turn suppresses your appetite, allowing you to reduce your calorie intake. 
  • GIP: This hormone helps to regulate energy balance and slow down the digestion of food, meaning you feel fuller for longer. 
Clinical studies for Mounjaro showed a 21% weight loss in adults using the highest dose, compared with 15% weight loss with the highest dose of Wegovy.
 
By reducing your calorie intake, you are able to lose weight more effectively than alternative methods.
What is Mounjaro?
Who is Suitable for Mounjaro? 
In December 2024, the NHS announced it would begin offering Mounjaro weight loss injections, however, only to those with the highest clinical need. It’s estimated that around 220,000 people will have access to the injection over the next three years. Mounjaro is however, available privately for those who wish to purchase the weight loss injection. 
 
  • Mounjaro is approved for a select group of patients with severe obesity:
  • BMI of over 30 (obese) 
  • Anyone with a BMI of over 27 who has at least one weight-related health problem, including diabetes, high cholesterol and high blood pressure.
  • Anyone with a BMI below this should consider alternative methods of weight loss. Injecting Mounjaro or any weight loss drug when your BMI is below the approved threshold could be dangerous, and you are likely to experience unnecessary side effects. 
 
Can you lose weight just from using Mounjaro? 
Most people who begin using Mounjaro will notice weight loss within the first few weeks. Due to the dramatic reduction in calories consumed, it’s common to experience weight loss without the need for exercise or dieting. This is not the recommended way to lose weight and sustain weight loss in the long term. 
 
It’s important to understand the psychology behind why people become overweight or obese. For many, it’s unhealthy eating habits and little to no exercise over a long period of time which causes them to gain weight. When taking Mounjaro, your ability to eat reduces dramatically because you don’t have the appetite to eat, or you will feel fuller much quicker and for longer. However, when you come off the injection, your appetite will return to normal. So if you haven’t made lifestyle changes throughout the process, the chances of regaining the weight you’ve lost are extremely high. 
 
Can you purchase Mounjaro Online?
There are lots of online pharmacies selling Mounjaro, but we would urge you to be extremely cautious when purchasing weight loss injections in this manner. Firstly, there are lots of counterfeit products being sold online which contain harmful ingredients or do not contain the active ingredient required for weight loss. Just because a product claims it is Mounjaro, doesn’t mean it is. Always purchase from reputable clinics or pharmacies so you can ensure legitimacy and safety. 
 
Mounjaro weight loss injections should be prescribed by a doctor or nurse prescriber who has seen you in person and has experience in managing weight loss patients. They should be given to patients with a BMI which falls within the approved range, and support should be offered throughout the process. Any reputable clinic will ensure you have regular follow-ups and support, encouraging you to make changes to your lifestyle and habits to ensure you sustain your weight loss long after Mounjaro. 
 
There are many cases where online pharmacies only request your height, weight and a picture of you. This is enabling thousands of weight loss injections to be prescribed to people whose BMI falls way below the approved and recommended range. This is extremely dangerous and not worth putting your health at risk. 
 
Will I put the Weight I Lose Back on when you come off Mounjaro?
Mounjaro helps to suppress your appetite and keep you feeling fuller for longer, helping you to reduce your calorie intake and in turn lose weight. When you stop taking Mounjaro, your normal appetite will return. This is where it’s important to address and change your eating and exercise habits to ensure sustained, long-term weight loss. If these habits are not altered, it is likely you will slowly gain the weight lost when you stop the injections. 
How do you inject Mounjaro?
How do you inject Mounjaro?
Mounjaro is a weekly weight loss injection which should be injected on the same day each week, each pen will last you four weeks. Every patient will be started on the lowest dose and moved up month by month after a check in with their medical professional. Some patients choose to stay on the same dose rather than moving up if they find it is effective for them. 
 
Here at MediZen we show all patients how to inject themselves when prescribing the first pen. The first dose of Mounjaro will be injected in this appointment so our doctor or nurse can ensure you inject correctly. Following this you will self-administer the injections on your chosen day each week. Some clinics may offer to inject for you each week if you struggle to do this yourself.
Is Mounjaro available on the NHS?
Mounjaro will be available to a very small number of patients through the NHS in 2025. Initially it will be offered to those with a BMI of over 35 with at least one obesity related health problem – potentially up to 3.4 million people. However the roll out will be slow and it is expected around 220,000 patients will benefit from Mounjaro in the first three years. 
 
For those who have a high BMI and are looking to lose weight but may not be a priority on the NHS, Mounjaro is available privately. 
 
How much weight can you lose on Mounjaro?
 
Clinical studies showed that patients on the highest dose of Mounjaro lost up to 22.5% of their starting body weight after 72 weeks on the injections. This figure will of course vary person to person and is dependent on diet, exercise, underlying health conditions and age. Those who lose the most weight will be the ones who maintain a balanced, healthy diet throughout, alongside regular exercise. 

If you want to read more, the experts at Consulting Room really know what they're talking about and have put together some weight loss injections and weight loss treatment FAQs just for you. 

If you have more questions, you can use the weight loss injections and weight loss information feature to talk to our panel of trained medical experts. 

If you're keen to get started with complexion improvement treatment right away, then you're in luck—those clever folks also have a list of trusted, accredited weight loss injections and weight loss information in your area.

MediZen was founded in 1999 by the worldwide trainer and key opinion leader for Allergan, Dr. David Eccleston, we are the Midlands Premier Aesthetic Clinic.

Medizen provide a range of treatments covering face, skin and body all with the aim of helping you feel your most confident self.

It is our firm belief that this can only be achieved in a medically led clinic such as ours.

Our Birmingham based clinic has a wide range of facilities that allow us to offer a variety of quality treatments from laser treatment to CoolSculpting®miraDry to skincare and lots more.

Give Medizen a call on 0121 392 8552 or visit medizen.co.uk for more information.

Thanks to the author

More great blogs our experts wrote for you...

Balancing Life with PCOS: Simple Habits That Make a Big Difference

15
May
2025

Balancing Life with PCOS: Simple Habits That Make a Big Difference

The lifestyle approach to PCOS: What really works?

Fad Diets for PCOS? Not So Fast!

06
May
2025

Fad Diets for PCOS? Not So Fast!

Losing weight is essential to controlling insulin resistance but following diet trends may not be the best approach!

What Are The Best Foods for PCOS

30
Apr
2025

What Are The Best Foods for PCOS

Struggling to manage PCOS through diet? The weight loss experts break down the best foods to support hormone balance, weight management, and overall wellbeing.


Hey, wait!

Before you go.....

Let's stay in touch, pop your details here and we'll send our editor's hand-picked updates on your fave subjects.