Pros and Cons of Weight Loss Injections such as Mounjaro and Wegovy

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August 27, 2025
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Pros and Cons of Weight Loss Injections such as Mounjaro and Wegovy

Home » Weight Loss Medication » Pros and Cons of Weight Loss Injections such as Mounjaro and Wegovy

Weight loss injections have become a popular option for people who struggle to manage their weight through diet and exercise alone. Unlike diet pills or over-the-counter supplements, these injections work by mimicking hormones that influence hunger and digestion¹. This can help users feel fuller for longer and ultimately help them to reduce their overall calorie intake.

Two of the most well-known options currently available are Mounjaro and Wegovy. Both are approved for weight management and have shown promising results. But while they can be an effective tool for some, they might not be right for everyone. So, in this guide, we explore how these injections work, their benefits and risks, and what to consider before starting treatment.

How do weight loss injections work?

Weight loss injections like Mounjaro – a brand name for tirzepatide – and Wegovy – a brand name for semaglutide – work by mimicking hormones that naturally occur in the body and help regulate hunger and blood sugar levels.

Wegovy is part of a group of drugs called GLP-1 agonists² which mimic a natural hormone that helps regulate appetite and food intake.

Mounjaro on the other hand is a dual GIP and GLP-1 receptor agonist³. This means it activates two hormone receptors – GIP and GLP-1 – that work together to influence the areas of the brain involved in appetite control.

By activating these hormone receptors, the injections help slow down digestion, reduce feelings of hunger and increase the feeling of fullness after eating, making it easier to consume fewer calories without constantly feeling hungry.

In addition to curbing appetite, weight loss injections can also improve how the body processes insulin and blood sugar⁴, which is particularly beneficial for people with type 2 diabetes or insulin resistance. Over time, this combination of reduced appetite and improved metabolism can support significant and sustained weight loss, especially when paired with healthy lifestyle changes.

Benefits of weight loss injections

There are a range of benefits to weight loss injections such as Mounjaro and Wegovy. Here some of the most common:

Effective weight loss results

Clinical trials and real-world data show that weight loss injections like Wegovy and Mounjaro can lead to significant results. Some lose up to 21% or more of their body weight in just 18 months⁵ when using these medications alongside healthy lifestyle changes.

If you’ve struggled to lose weight through diet and exercise alone, injections can be a powerful tool to help you reach your goals.

Support for long-term weight management

One of the key advantages of these medications is their ability to support sustained weight loss. Unlike crash diets or other similar quick fixes, weight loss injections work by changing how the body regulates hunger and fullness⁶, making it easier to stick to healthier habits over time.

With ongoing use under medical supervision, many users are able to maintain their weight loss and improve related health conditions such as type 2 diabetes, high blood pressure and sleep apnoea.

Convenience

Weight loss injections are designed to be simple and easy to use as part of your general routine. Most are taken just once a week using a pre-filled injection pen⁷.

Benefits include:

Once-weekly dosing, so no daily pills to remember

Self-administered at home, meaning no need for regular clinic visits

Pre-filled pens which are ready to use, with no measuring or mixing required

Small injection usually into the stomach, thigh or upper arm

So if you lead a busy lifestyle and want a hands-off approach to weight management, these weight loss injections can be a practical option to fit in around your schedule.

Potential drawbacks

While weight loss injections can offer real benefits, they may not be the right fit for everyone. It’s important to consider any potential side effects, the cost of the pens and how easily you can access treatment before deciding if they’re the right choice for you.

Side effects and health risks

While weight loss injections can be effective, they’re not without side effects. Most are mild and tend to improve over time, but some users may experience more serious issues. It’s important to speak to a healthcare professional before starting treatment and during if you begin to notice anything unusual.

Common side effects include⁸:

Nausea

Diarrhoea or constipation

Headaches

Heartburn

Fatigue

Indigestion or heartburn

Injection site reactions

Less common but more serious risks may include⁹:

Gallbladder issues (such as gallstones)

Pancreatitis

Increased heart rate

Acute sudden kidney failure

Depression

Low blood sugar levels

Not everyone will experience these side effects, but it’s important to weigh the risks and benefits based on your own health record.

Cost considerations: How much are weight loss injections?

Weight loss injections can be expensive, particularly if you’re paying privately. Prices vary depending on the medication, dose and provider, but on average:

Wegovy starts at around £125 per month¹⁰, depending on dosage

Mounjaro starts at around £149 per month¹¹, but may vary based on availability and supply

NHS access is limited to those who meet strict eligibility criteria, so many people choose to buy injections through private providers – adding to the overall cost of treatment.

Accessibility: Where can I buy weight loss injections?

If you’re eligible, weight loss injections may be prescribed through the NHS, but access is limited and subject to local guidelines. If you’re seeking private treatment, options include online health clinics, pharmacies and regulated services like myBMI.

At myBMI, we offer a personalised, medically supervised weight loss programme that includes access to treatments such as Wegovy and Mounjaro, where clinically appropriate.

Our service includes:

Initial health assessment

Ongoing medical support

Easy-to-use injection pens delivered to your door

Always make sure you’re buying from a licensed and regulated provider, as unregulated sources can pose serious risks to your health.

Eligibility and access

Who is eligible for weight loss injections?

Weight loss injections are typically prescribed privately for adults who¹²:

Have a BMI of 30 or above, or

A BMI of 27 or above with a weight-related health condition such as type 2 diabetes, high cholesterol or sleep apnoea

A healthcare provider will assess your overall health, medical history and weight loss goals before deciding if treatment is suitable for you.

Eligibility criteria may vary if you’re accessing the medication through the NHS.

How to get weight loss medications

If you’re considering weight loss injections, the first step is a medical assessment. This can often be completed online through trusted clinics or in person with your GP.

myBMI offers a streamlined, clinically led service where, if eligible, you can receive treatment, support and follow-up care from the comfort of your own home.

Weighing the pros and cons

Before starting any medication, it’s important to weigh up whether it aligns with both your needs and lifestyle. Here’s a quick summary to help you think it through:

Pros:

Clinically proven weight loss

Appetite regulation makes it easier to stick to healthy habits

Weekly dosing with simple self-injection

Cons:

Potential side effects

High monthly cost (especially privately)

May not be suitable for everyone

Making an informed decision

Weight loss injections can be a valuable tool – but they’re just one part of a bigger picture. Understanding how they work, what to expect and whether they fit your long-term health goals is key.

If you’re still unsure, speak to a qualified provider or your GP to explore your options and find a treatment plan that works for you.

What lifestyle changes should I consider?

While jabs like Mounjaro and Wegovy can help speed up weight loss – they’re most effective when combined with healthy lifestyle habits. If you make sustainable changes to how you eat, move and live, it can help you get the best results and maintain them in the long term.

Healthy eating habits

Focus on balanced meals that include lean proteins, whole grains, healthy fats and plenty of fruit and veg. Injections may reduce appetite, but it’s still important to nourish your body with the right nutrients. Smaller portions and reducing how much processed food you eat can all support your progress.

Regular physical activity

You don’t need to start running marathons, but regular movement helps boost metabolism and preserve muscle mass. Aim for at least 150 minutes of moderate exercise per week – such as brisk walking, swimming or cycling – plus strength-based activity a couple of times a week¹³.

Sleep and stress management

Poor sleep and high stress can disrupt hormones that affect appetite and weight. Prioritise quality sleep and find ways to manage stress, whether through relaxation techniques, social support or gentle activities like yoga or stretching.

Long-term mindset

Injections can give you a head start, but long-term success comes from building habits that feel realistic and repeatable. Set achievable goals, celebrate small wins and don’t be discouraged by occasional setbacks – they’re part of the journey!