How Does Wegovy Work For Weight Loss?

Losing weight is never just about willpower – it’s a complex journey that involves your biology and lifestyle. So if you’ve been struggling with obesity or carrying extra weight you’re not alone. Sometimes, you need a little extra support, even if you’re eating well and exercising.

In recent years, new medications have emerged that can support safe and effective weight loss. One such medication is Wegovy.

Available in the UK on prescription, Wegovy has gained a lot of attention for helping people lose weight. But how does it actually work? What can you expect from it? And how does it compare to other treatments like Mounjaro or Saxenda?

Here, we’ll break it down. So you can get a better idea of whether it’s the right choice for you.

What is Wegovy?

Wegovy, which contains the active ingredient semaglutide, is a prescription-only medicine. It supports weight loss in adults who are overweight or obese, when combined with healthy lifestyle changes. You inject it once a week.

Wegovy was approved for use in the UK in 2023 and is typically prescribed for people who:

• Have a BMI of 30 or more; or
• Have a BMI of 27 or more with at least one weight-related health condition. For example type 2 diabetes, high blood pressure, asthma, PCOS, erectile dysfunction or high cholesterol.

Wegovy is not a quick fix. You use it alongside diet, exercise, and behaviour changes to help you manage your weight long-term.

How Does Wegovy Work?

Wegovy belongs to a class of medicines called glucagon-like peptide 1 (GLP-1) receptor agonists.

“Wegovy mimics a natural hormone called GLP-1,” explains Abdal Alvi, Simple’s Chief Clinical Officer.

“It works on the part of the brain that controls hunger, helping you feel full quicker and for longer. It also slows how food moves through your stomach and reduces cravings, especially for high fat and high sugar things like chocolate and cakes.”

So it helps you lose weight in three main ways:

1. Reduces Appetite: It helps reduce hunger by acting on the appetite centres in your brain. This helps you feel fuller more quickly and stay satisfied for longer after eating.
   
2. Slows Down Digestion: Wegovy delays the emptying of your stomach. Food stays in your stomach longer. This contributes to prolonged feelings of fullness and less frequent snacking or overeating.
   
3. Improves Insulin Sensitivity: It helps regulate blood sugar levels. This can reduce cravings and prevent energy crashes that often lead to overeating.

Over time, these effects lead to you eating more appropriate portions of healthier foods. This supports steady and sustainable weight loss.

Wegovy’s Effect on Heart Health

Interestingly, Wegovy doesn’t just support weight loss. Emerging research has shown it may also benefit your heart health.

In a major trial (SELECT), researchers discovered that semaglutide (Wegovy) lowered the risk of serious heart events. These events include heart attacks and strokes in people who are overweight or obese and have heart disease.

This makes Wegovy an exciting option for people looking to manage both their weight and improve their heart health.

How to Take Wegovy

You take Wegovy once a week as a subcutaneous injection (under the skin). You usually inject it into the upper arm, thigh, or abdomen. You need to see the window of the pen as you inject. So, if you’re injecting into the upper arm, you might have to get someone to do this for you.

Wegovy comes in pre-filled pens containing four doses, which will last you four weeks. It’s designed to be easy to use at home.

To minimise common side effects and help your body adjust, your clinician will start you on a low dose of Wegovy. They’ll gradually increase it over time, which is known as titration.

A typical dose titration schedule might look like this:

• Week 1–4: 0.25 mg once weekly
• Week 5–8: 0.5 mg once weekly
• Week 9–12: 1 mg once weekly
• Week 13–16: 1.7 mg once weekly
• Week 17 onwards: 2.4 mg once weekly (maintenance dose)

However, no two weight loss journeys are the same. Your prescriber may adjust this based on how you respond and whether you experience any side effects.

Do I Still Need to Eat Well and Exercise to Lose Weight?

Yes. Wegovy works best when you combine it with a healthy diet and physical activity. The medication can reduce your appetite, making it easier to eat less. However, it won’t replace the need for lifestyle changes.

Keeping the weight off long-term depends on building sustainable, healthy habits. That’s why it’s important to focus not just on taking the medication, but also on the choices you make each day.

These following habits can work alongside Wegovy to help you feel better, eat smarter, and move more:

• Eat a Balanced Diet: Eat plenty of vegetables, whole grains, and lean protein. This will nourish your body, help side effects and support your appetite.
  
• Be Active Most Days: The UK government recommends at least 150 minutes of moderate exercise each week. This might be brisk walking, swimming, or cycling.
  
• Stay Hydrated and Get Enough Sleep: Both of which affect your metabolism, mood, and hunger levels.

• Mindful Eating: Healthy eating isn’t just about what you eat, but why you eat. Being aware of your body’s hunger cues will help you eat for your needs, rather than to suppress emotions.

“Try to make small changes to your lifestyle each week. Look at the list above for ideas and think about what improvements you could make,” says Richard Wood, a pharmacist at Simple.

“A lot of patients we speak to have more success making small changes that add up over time, rather than making huge changes all at once.”

What Results Can You Expect With Wegovy?

Clinical trials show people taking the highest Wegovy dose lose an average of 17% of their body weight after around 68 weeks. So if you weigh 100 kg, that could mean losing around 17 kg in just over a year.

Many people also see improvements in blood pressure, cholesterol levels, sleep quality, and energy levels.

Keep in mind that individual results vary. Some people lose more, some lose less. But most experience noticeable improvements in weight and wellbeing.

Side effects such as nausea, constipation, or diarrhoea are relatively common. They’re particularly common at the start of treatment. But they often improve over time.

How It Works Compared to Other Weight Loss Treatments

Wegovy is not the only weight loss medicine available in the UK. Let’s take a quick look at how it compares to other commonly prescribed options.

Mounjaro (tirzepatide)

• Mounjaro is another weekly injection, recently approved in the UK.
• Unlike Wegovy, it targets two receptors: GLP-1 and GIP.
• Patients on the highest dose of Mounjaro (15 mg) tend to lose slightly more (22.5% of starting weight) compared to patients on the highest dose (2.4 mg) of Wegovy (17%).

Saxenda (liraglutide)

• Saxenda is a daily injection rather than weekly.
• It’s also a GLP-1 receptor agonist, but Wegovy tends to lead to more weight loss.
• Some patients may prefer Saxenda, especially if they don’t tolerate semaglutide.

Orlistat (Alli or Xenical)

• Orlistat works by blocking fat absorption in the gut.
• You take a tablet three times daily with meals.
• It’s less effective overall and often causes side effects, like oily stools or urgency.

Always speak to your GP or a registered pharmacist before starting any weight loss treatment. They will ensure it’s safe and suitable for you.

Key Takeaways

• Wegovy (Semaglutide) is a Weekly Injection: It’s used for weight loss in adults with a BMI of at least 27.
• It Works by Mimicking the Hormone GLP-1: This reduces appetite, slows digestion, and improves insulin sensitivity.
• Combine it With Lifestyle Changes: With a healthy diet and regular exercise, Wegovy can lead to significant weight loss. Patients can lose on average around 17% of starting body weight.
• It Also Benefits Heart Health: A major study found it can reduce the risk of major heart events (heart attack, stroke).
• The Effects of Wegovy are Generally Well-Tolerated: Some people may experience nausea or stomach upset at first.

References

NICE. Overview | Overweight and obesity management | Guidance | NICE. 2025. Available from: https://www.nice.org.uk/guidance/ng246.

CDC. SUMMARY OF PRODUCT CHARACTERISTICS. Wegovy. Available from: https://www.ema.europa.eu/en/documents/product-information/wegovy-epar-product-information_en.pdf.

VV-LAB-123016. SUMMARY OF PRODUCT CHARACTERISTICS. Ozempic. Available from: https://www.ema.europa.eu/en/documents/product-information/ozempic-epar-product-information_en.pdf.

Wilding JPH, Batterham RL, Calanna S, Davies M, Van Gaal LF, Lingvay I, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. New England Journal of Medicine. 2021 Feb 10;384(11):989–1002. Available from: https://doi.org/10.1056/nejmoa2032183.

Davies M, Færch L, Jeppesen OK, Pakseresht A, Pedersen SD, Perreault L, et al. Semaglutide 2·4 mg once a week in adults with overweight or obesity, and type 2 diabetes (STEP 2): a randomised, double-blind, double-dummy, placebo-controlled, phase 3 trial. The Lancet. 2021 Mar 1;397(10278):971–84. Available from: https://doi.org/10.1016/s0140-6736(21)00213-0.

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Jastreboff, A.M., Aronne, L.J., Ahmad, N.N., Wharton, S., Connery, L., Alves, B., Kiyosue, A., Zhang, S., Liu, B., Bunck, M.C. and Stefanski, A. (2022). Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine, [online] 387(3). doi:https://doi.org/10.1056/nejmoa2206038.

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