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How Quickly Does Mounjaro Work?

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How Quickly Does Mounjaro Work?

02 / Jul

Mounjaro, with its active ingredient tirzepatide, represents a significant advancement in the pharmacological management of weight. This medication has recently become available to eligible NHS patients in England, offering a new avenue for individuals struggling with obesity and weight-related health conditions. Administered as a convenient once-weekly self-injection, Mounjaro offers a structured approach to weight management when used under medical supervision

What is Mounjaro?

Mounjaro is different from older weight loss medicines because it works in a unique way. It acts like two natural gut hormones, called GIP (gastric inhibitory polypeptide) and GLP-1 (glucagon-like peptide-1), which your body releases after you eat. By mimicking these two hormones, Mounjaro sends messages to your brain that make you feel full, helping to curb your appetite and reduce food cravings. It also helps slow down how quickly your stomach empties and helps control your blood sugar levels. All these actions together lead to you eating less food, helping you lose weight.

Because Mounjaro targets two pathways instead of just one (like older medicines such as semaglutide, found in Ozempic or Wegovy), it can be more effective. This dual action helps better control blood sugar and leads to more significant weight loss. For instance, studies have shown that Mounjaro can be twice as effective as Wegovy for weight loss, especially for people also taking metformin. This shows we’re learning more about how gut hormones affect our metabolism, and this dual approach offers a more complete and lasting way to manage chronic conditions like obesity and Type 2 diabetes.

How Quickly Does Mounjaro Start to Work?

Mounjaro begins working in your body soon after your first injection, often within hours. Some people even notice initial effects, such as feeling fuller after eating, in as little as 12 hours. This quick start is because the medication immediately interacts with specific receptors in your body that help manage appetite and blood sugar.

While these internal processes begin quickly, you will typically notice more significant changes, like reduced appetite and the start of weight loss, over the first few weeks of treatment. For those with Type 2 diabetes, lower blood sugar levels are generally observed around four weeks after starting Mounjaro.

It’s important to understand the difference between the drug starting to work quickly and seeing noticeable results. The drug’s internal actions begin almost immediately, but the more observable outcomes, such as significant weight loss, take time to develop as your body adjusts to the medication. This understanding helps set realistic expectations for your treatment journey.

When Can You Expect to See Weight Loss Results?

In the Early Weeks

During the first two to four weeks of Mounjaro treatment, while on the lowest starting dose of 2.5mg, any weight loss experienced is likely to be modest. This initial period is primarily dedicated to allowing the body to adapt to the medication. It is during this phase that individuals may first notice a decrease in appetite, which lays the groundwork for future weight reduction.

It is also common to experience some of Mounjaro’s initial side effects, such as nausea, diarrhoea, or constipation, as the body adjusts to the medication.

Longer-Term Outcomes

Clinical studies have demonstrated impressive and sustained weight reductions over longer treatment durations, particularly over 72 weeks.

Average weight loss observed in clinical trials (over 72 weeks) includes:

  • For individuals taking the 5mg dose, an average of approximately 16% of their total body weight was lost.
  • Those on the 10mg dose saw an average reduction of about 21.4% of their total body weight.
  • Patients on the highest 15mg dose experienced the most significant loss, averaging 22.5% of their total body weight.

How Much Weight Should I Aim to Lose on Mounjaro?

It’s important to understand that Mounjaro is not a “quick fix” for weight loss. The significant weight loss seen in studies, like losing up to 22.5% of starting body weight, happened gradually over a longer period, typically around 72 weeks (about 1.5 years).

The goal with Mounjaro should be steady, sustainable weight loss, which is usually considered to be about 1 to 2 pounds (0.5 to 1 kg) per week. This gradual approach is healthier and more likely to lead to results that last.

Instead of focusing on restrictive “fad diets” that are often hard to stick with and might not provide enough nutrients, the emphasis should be on adopting a healthy, balanced diet that you can maintain over the long term. This helps you build healthier habits that can continue even after you stop taking the medication.

How to Successfully Lose Weight on Mounjaro

Stick to your dosing schedule

To ensure Mounjaro works effectively and maintains stable levels in your body, it is essential to inject your dose once a week, on the same day, and at the same time.

Your healthcare clinician will discuss with you when to increase the strength. You start on 2.5mg once weekly and increase by 2.5mg every month until a maintenance dose is reached, this is usally 5mg, 10mg, or 15mg depending on how your body reacts to and how strong the side effects are.

Make sure you have a balanced diet

Mounjaro isn’t a standalone solution; it’s designed to be used with a balanced diet and regular exercise. It’s not a substitute for making these important lifestyle changes. As part of the NHS Eatwell Guide:

  • Consume at least five portions of a variety of fruit and vegetables every day.
  • Base meals on higher-fibre starchy foods, choosing wholegrain options like brown rice, wholewheat pasta, and wholemeal bread.
  • Include dairy or fortified dairy alternatives, lean protein sources such as beans, pulses, fish, eggs, and lean meats, and use unsaturated oils and spreads in small amounts.
  • Limit the intake of foods and drinks that are high in fat, salt, and sugar. The aim should be to ensure no more than 30% of daily calories come from fat.

To support dietary goals, consider planning meals in advance, creating comprehensive shopping lists, and bulk cooking meals for convenience. Avoid grocery shopping when hungry, use smaller plates to help with portion control, and minimise eating in front of screens to prevent mindless consumption.

Get plenty of exercise

Exercise must be added to your routine if you are planning on using Mounjaro. Regular exercise not only aids in weight loss by increasing calories burnt but also offers numerous benefits for overall health and wellbeing.

For adults, it’s recommended to accumulate at least 150 minutes (2.5 hours) of moderate-intensity aerobic activity each week (e.g., brisk walking, cycling), or 75 minutes of vigorous-intensity activity (e.g., running). Additionally, it’s advised to include muscle-strengthening activities on at least two days a week and to reduce extended periods of sitting. Beyond weight management, regular physical activity can improve heart and lung health, strengthen bones, and significantly boost mood and confidence.

Explore the NHS Fitness Studio for a range of home workout videos or the NHS Couch to 5K Programme to help build up running 5 kilometres non-stop

Stay Hydrated

Maintaining adequate hydration is a an important measure, particularly when starting Mounjaro treatment. Gastrointestinal side effects such as vomiting, nausea, and diarrhoea are common, especially in the initial phases, and can lead to fluid loss and dehydration.

Aim for good levels of hydration by consuming 8-11 cups of liquid per day (approximately 2.7 litres).Water, lower-fat milk, and sugar-free drinks like tea and coffee all count towards daily fluid intake

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