Mounjaro Injections for Weight Loss: Everything You Need to Know

If you’ve been exploring new options to support weight loss, you’ve likely come across Mounjaro—a weekly injection that’s quickly gaining attention for its impressive results. Designed to help manage food cravings, improve eating habits, and target excess weight, Mounjaro is part of a new generation of medically approved treatments.

But what is it exactly, how does it work, and is it right for you?

In this in-depth guide, we’ll walk you through everything you need to know about Mounjaro (tirzepatide)—from how it supports sustainable weight loss to how you can access it in the UK.

What Is Mounjaro for Weight Loss and How Does It Work?

Mounjaro is a brand name for tirzepatide, a medication developed by the pharmaceutical company Eli Lilly. Originally designed to treat type 2 diabetes, Mounjaro has now been authorised in the UK as a weight management aid for individuals with obesity or weight-related health conditions.

Approved by the MHRA in 2023 and released to the UK market in 2024, Mounjaro offers an exciting alternative for those who haven’t seen success with diet, exercise, or other weight-loss medications.

What makes Mounjaro different is its dual-action approach. It mimics two hormones—GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide)—which play key roles in hunger regulation and metabolism. By targeting both pathways, Mounjaro offers a powerful combination that suppresses appetite, improves insulin sensitivity, and promotes sustained weight loss.

How Mounjaro Supports Appetite Control and Metabolism

After a meal, your body naturally produces GLP-1 and GIP to help regulate blood sugar and tell your brain you’re full. Mounjaro enhances these effects by:

• Suppressing appetite: It helps reduce hunger signals in the brain, especially in the hypothalamus, making you feel satisfied with smaller portions.
• Slowing digestion: By slowing the movement of food from the stomach to the intestines, Mounjaro prolongs the feeling of fullness.
• Controlling blood sugar: It increases insulin release after meals and reduces glucagon, a hormone that raises blood sugar.

This multi-action process helps people lose weight more effectively by addressing both appetite and metabolism. In addition to supporting long-term weight management, Mounjaro also improves metabolic health—making it a powerful choice for individuals with insulin resistance, prediabetes, or type 2 diabetes.

Who Can Use Mounjaro to Lose Weight Safely?

In the UK, Mounjaro is licensed for adults who meet one of the following criteria:

• A mass index (BMI) of 30 or above (classified as obese)
• A body mass index between 27 and 29.9 with at least one weight-related health issue, such as:
• High blood pressure
• High cholesterol
• Type 2 diabetes or prediabetes
• Cardiovascular disease
• Sleep apnoea

Before starting treatment, you’ll need to complete a medical consultation with a prescriber. This ensures the medication is safe and appropriate for your individual health profile.

How to Use Mounjaro: Dosage, Injections, and Lifestyle Adjustments

Mounjaro is self-administered as a weekly injection, using a pre-filled pen. It’s injected just under the skin (subcutaneously), usually in the thigh, stomach, or upper arm. The pen is designed for ease of use, and many patients find it convenient and virtually painless. 

Each pen contains four doses—one per week—so you’ll typically need one pen per month. You can inject it at any time of day, with or without food.

Mounjaro Dosage Guide: What People Lose at Each Stage

When you begin Mounjaro, your treatment typically starts with the lowest available dose—2.5mg once a week. This is part of the initiation phase commonly used in weight loss medications and injections and, allowing your body to adjust gradually and reducing the risk of side effects.

After four weeks, your prescriber may increase your dose to 5mg. If you respond well and further weight loss is needed, your dose may be increased every four weeks to:

• 7.5mg
• 10mg
• 12.5mg
• Up to a maximum of 15mg once a week

Not everyone needs to reach the highest dose. Many people see effective results at mid-range levels, depending on individual response and tolerability. Mounjaro works by influencing brain and fat cells to regulate appetite, improve insulin function, and support long-term weight reduction. This gradual dosage increase—called titration—helps the body adapt to treatment while optimising both safety and effectiveness.

How Much Weight Can You Expect to Lose with Mounjaro?

Clinical studies and real-world reports have been very promising. In a major 2022 trial (SURMOUNT-1), participants using tirzepatide lost up to 22.5% of their body weight over a 72-week period. For many patients, that meant losing more than 50 pounds.

To compare:

• Tirzepatide (Mounjaro) users: ~22.5% average body weight loss
• Semaglutide (Wegovy) users: ~15% average weight loss

What’s more impressive is that a majority of users lost at least 5% of their body weight, a clinically significant benchmark that can improve health outcomes like blood pressure, cholesterol, and insulin sensitivity.

However, results vary from person to person. Weight loss also depends on other factors like your diet, activity levels, genetics, and consistency with treatment.

Can Mounjaro Cause Weight Gain or Other Side Effects?

As with most medications, Mounjaro can cause side effects—especially in the early stages or when increasing the dose. Most are mild and resolve as your body adapts. Common side effects include:

• Nausea
• Diarrhoea
• Reduced appetite
• Vomiting
• Constipation
• Bloating or indigestion
• Stomach discomfort

Some people may experience "sulphur burps" or gas due to slowed digestion. Staying hydrated, eating smaller meals, and avoiding greasy or spicy foods can help manage symptoms. Speak to your healthcare provider if any side effects persist or become bothersome.

Diet and Exercise Support

Although Mounjaro is effective on its own, especially when compared to other diabetes medications, it works best when paired with thoughtful lifestyle changes. This isn’t about crash dieting or punishing workouts—it’s about improving your energy balance through sustainable habits that support long-term success.

Clinical trials have shown that combining Mounjaro with healthy routines significantly improves outcomes, both in weight reduction and blood sugar control, especially for those already using diabetes medications.

Diet tips while on Mounjaro:

• Focus on lean protein, fibre, and whole foods to support a balanced diet
• Limit high-sugar and ultra-processed foods that can spike insulin
• Eat smaller, slower meals to improve digestion and appetite awareness
• Stay well hydrated throughout the day

Exercise recommendations:

• Aim for at least 150 minutes of physical activity per week
• Include resistance training to preserve lean muscle and boost metabolism
• Add activities like walking, swimming, yoga, or cycling to keep it enjoyable

Achieving the right energy balance—consuming fewer calories than you burn—is key to sustained fat loss. Without sufficient protein and strength training, you risk losing muscle along with fat, which can slow your metabolism. Mounjaro helps by regulating hunger and glucose, but maintaining a balanced diet and active lifestyle is what locks in your results for the long haul.

How to Get Mounjaro in the UK

Mounjaro is available privately in the UK following a short medical consultation with a licensed prescriber. At our pharmacy, you can begin your journey in three simple steps:

1. Complete a free online consultation
2. Get approved by a qualified prescriber
3. Receive your treatment discreetly at home

Prices for Mounjaro typically start from £124 per pen (four doses), depending on the dose prescribed. The NHS is expected to offer Mounjaro starting in 2025, initially for those with a BMI over 35 and weight-related health problems. Until then, private providers like us can help eligible patients access treatment.

Final Thoughts

Mounjaro isn’t a quick fix—but it is a powerful, science-backed weight loss treatment that supports long-term success. As an injectable medication, Mounjaro helps suppress appetite, regulate hunger signals, and improve blood sugar regulation, making it easier to achieve and maintain a healthy weight.

It works by targeting key hormones to control blood sugar levels and prolong the feeling of fullness, giving you a genuine advantage in your journey. When used alongside a healthy lifestyle, Mounjaro offers a safer, more sustainable option compared to some other weight loss drugs or other weight loss injections on the market.

We offer a trusted weight loss service designed to guide and support you from your first consultation to your final result.

Ready to take the first step toward a healthier you?
Start your consultation today and discover if Mounjaro is the right weight loss treatment for your goals. We’re here to support your progress—every step of the way.