How does Wegovy work?

Dr. Babak Ashrafi

Medically reviewed by

Dr Babak Ashrafi

Last reviewed: 05 Feb 2024

Wegovy is a prescription weight loss injection that can help you reduce the amount of calories you take in by suppressing your appetite. It is effective for over 80% of those who take it, and can help you lose over 20% of your body weight while taking it. Read more to learn how Wegovy works, how effective it is, and whether it could be the right option for you.

If you want information about our weight loss service, please visit our Weight Loss FAQ page. Here, we cover questions about our weight loss programmes and provide additional information on our medications, side effects and ordering processes.

Wegovy 2.4 mg injection pen

What is Wegovy used for?

Wegovy is used to help people who are obese and have struggled or are unable to lose weight through other weight loss strategies, such as dieting and exercise. It is also used for overweight people with certain health conditions such as high blood pressure and high cholesterol that can make it difficult to lose weight.

Semaglutide, the active ingredient in Wegovy, may also be used to help people with diabetes to regulate their blood sugar levels. Wegovy is not a currently approved treatment for diabetes in the UK, but a similar medication called Ozempic is used to treat diabetes.

How does Wegovy work in the body?

Wegovy contains the active ingredient semaglutide, which is a medication that mimics a naturally occurring hormone produced in the intestines called glucagon-like peptide-1 (GLP-1). This hormone helps to regulate your blood sugar levels by increasing the amount of insulin your body produces, as well as by decreasing the amount of glucose produced in your liver. This hormone is also responsible for receptors in your brain that control and regulate your appetite. Semaglutide will reduce your appetite and make you feel fuller and more satisfied after a meal, so you do not need to eat as much.

How does Wegovy work for diabetes?

Wegovy is currently not an approved treatment for diabetes in the UK, but a similar medication called Ozempic is, which also contains the active ingredient semaglutide. This medication treats diabetes by helping your body to regulate your blood sugar level. It does this by increasing the amount of insulin produced in your pancreas, and decreasing the amount of glucose produced in your liver.

How does Wegovy work for insulin resistance?

Insulin resistance is a term used to describe when your body is not able to properly process the insulin that your body produces, or you inject yourself with. This means that your body needs to produce more insulin to convert the sugar in your blood into energy. Wegovy helps your body overcome insulin resistance by reducing the amount of glucose you produce, meaning you need less insulin and are at a lower risk of insulin resistance.

How does Wegovy work for weight loss?

Wegovy works for weight loss by reducing your appetite, and making you feel fuller after a meal. This means that you do not need to eat as much, so you take in fewer calories. It also helps your body more efficiently convert blood sugar into energy, rather than fat.

How much weight can you lose in a week with Wegovy?

The amount of weight you lose when taking Wegovy will be different for everyone, and may also change on a weekly basis as your Wegovy dosage increases.

On average, you can expect to lose around:

  • 6% of your starting weight after 12 weeks of taking Wegovy
  • 10% of your starting weight after 20 weeks
  • 15% after a year

Will my doctor prescribe Wegovy for weight loss?

“Wegovy is only prescribed to those who have a BMI of 30 or higher, or over 27 if they have a weight-related health risk factor such as high blood pressure or high cholesterol. Wegovy is also usually only prescribed to those who have attempted to lose weight in the past but have been unsuccessful, or have difficulty losing weight through exercise and dieting alone.” – Dr Babak Ashrafi, Clinical Lead for Service Expansion at ZAVA.

In some cases, such as if you are allergic to any of the ingredients, a doctor may not recommend Wegovy. Fortunately, there are a number of alternative weight loss medications that may be more suitable for you such as Mounjaro, Mysimba, Xenical, and Orlistat.

Wegovy clinical studies

Clinical studies have proven that Wegovy is a highly effective weight loss medication, and can help you lose weight better than other weight loss treatments. Some studies have shown average weight loss to be around 15% of starting body weight, with expected weight loss to be between 9.7kg and 15.3kg over the course of a year. Up to 30% of people who take semaglutide can expect to lose 20% or more of their body weight.

In addition to being highly effective for weight loss, semaglutide also shows improvement in overall cardiovascular health and self-reported physical functioning. While this is a direct result of losing weight, it is also reported to be more prevalent in those taking semaglutide for weight loss than those who take other medications, or no medication at all. This is because semaglutide helps to regulate blood sugar levels.

How long does it take for Wegovy to work?

Wegovy injections usually start to work after around 2 weeks, and you should begin to feel fuller after a meal by the second or third dose. You should notice weight loss results within 8 to 12 weeks of starting Wegovy, though some people may take a little longer to see visible results.

If you have been taking Wegovy for 6 months and haven’t lost a significant amount of weight, you should speak to your doctor to explore other treatment options.

At what dose does Wegovy start working?

For most people Wegovy starts working from the starting dose of 0.25mg per week, which is gradually increased. However, some people may find that they do not have any noticeable weight loss until they start taking a higher dosage.

What dose of Wegovy works best?

The highest dosage of Wegovy is usually the most effective for weight loss. However, you cannot take the highest dosage straight away. Your dosage of Wegovy will be gradually increased over time, from 0.25mg per week up to 2.4mg per week.

Can you skip to higher doses of Wegovy?

No, you shouldn’t increase your dosage of Wegovy unless you speak to your doctor first. This is because your body may not be able to safely tolerate a higher dosage, and could result in unwanted side effects.

Does Wegovy work for everyone?

Wegovy has been shown to be a safe and effective treatment for most people who take it, but it is not suitable for everyone. According to the manufacturer, 83% of adults taking Wegovy lost at least 5% of their starting body weight.

Will Wegovy stop working?

Wegovy is a medication that is designed to be taken long term, but it is normal for your weight loss to slow down over time. This is because your body will get used to the medication over taking it for a long period of time, and it will get less effective. It is also normal to hit “plateaus” during a course of Wegovy, in which case you may need to move on to a higher dosage if you have not hit your weight loss goal and are not yet on the maximum dose of 2.4mg.

However, if your weight loss slows down or plateaus, it doesn’t necessarily mean that Wegovy has stopped working. It may mean that your metabolism is slowing down or you need to work on building muscle mass, as muscles burn more calories at rest than fat.

Why is Wegovy not working for me?

Wegovy is a medication that is effective for most people who take it, but some people may still find that they are struggling to lose weight on this medication. Some reasons for this may be:

  • You need to make complementary lifestyle changes – Wegovy helps you lose weight by reducing your appetite, but you will still need to make healthy lifestyle choices such as dieting and exercise. Try to eat less fatty foods, snack less between meals, and exercise for at least 30 minutes a day to see the best results from Wegovy.
  • You are not taking Wegovy properly – you need to remember to take Wegovy every week, and increase your dosage in line with your prescription. If you miss a dose, or take a lower dosage than prescribed, then you will have a lower concentration of semaglutide in your body which may slow down or stop your weight loss.
  • Your body may not respond well to Wegovy – while most people find Wegovy to be an effective medication for weight loss, it does not work for everyone. Over 83% of people successfully lose weight with Wegovy, which means that it isn’t effective for around 17% of people. If Wegovy doesn’t work for you, there are other weight loss treatments that may be a better option.

Does Wegovy work as well as Mounjaro?

Mounjaro is a treatment for weight loss and type 2 diabetes that contains the active ingredient tirzepatide. It works similarly to Wegovy by reducing appetite, and some studies suggest it is actually a slightly more effective treatment. Please keep in mind that trials and reviews of trials may not apply to your individual health situation.

Does Wegovy work better than Saxenda?

Saxenda is a weight loss injection that contains the active ingredient liraglutide. It also works similarly to Wegovy, by making you feel less hungry and fuller after a meal. However, Saxenda is a daily injection, while Wegovy is a weekly injection. Studies suggest that Wegovy is a more effective weight loss medication than Saxenda.

Does Wegovy work better than Ozempic for weight loss?

Wegovy and Ozempic are both medications that contain the active ingredient semaglutide, but are used to treat different conditions. While Wegovy is used for weight loss, Ozempic is only approved for type 2 diabetes and is not approved as a weight loss treatment. Ozempic is also usually prescribed at a lower dosage than Wegovy, so it is a less effective medication for weight loss for most people than Wegovy.

Weight loss medication table: Type, Active Ingredient, how it works and how often to take it

What diet works best with Wegovy injections?

Wegovy helps you cut weight by reducing your appetite, but you still need to maintain a healthy diet to keep the weight off. Some changes you can make to your diet to get the best results with Wegovy include:

  • Reduce your portion sizes – this is something that will naturally happen when taking Wegovy, as you will feel fuller after meals and not need to eat as much.
  • Switch to leaner cuts of meat – try to eat more meats such as skinless chicken breast or turkey. If you are eating other types of meat, trim off any visible fat or remove skin.
  • Go for low-fat alternatives to dairy products – semi-skimmed milk, reduced-fat cheeses, or low-fat butters and margarines are lower calorie alternatives to full fat options. In some cases, switching to dairy-free alternatives such as almond milk can cause significant calorie reductions.
  • Reduce how much you drink – alcohol is surprisingly high in calories, so cutting down on how much you drink can help keep the weight off.
  • Try not to snack between meals – while you will feel less need to snack while on Wegovy, sticking to a regular meal plan and eating only during your main meals will help you track and control your calorie intake.
  • Add more vegetables to your meals – as you will feel more full after eating less, it is important to fill up on nutritious foods. Adding more veggies to your meals is the easiest way to get these important nutrients.

➤ More information on this can be found here: What Foods to Avoid When Taking Wegovy and the Best Food to Eat on Wegovy

What are the long-term side effects of using Wegovy?

While it isn’t common, it is possible for Wegovy to cause long term side effects. These include an increased risk of pancreatitis. These side effects will usually subside shortly after stopping Wegovy, so if you are experiencing any issues while taking the medication speak to your doctor immediately.

How can I reduce the side effects of Wegovy?

Some people may find that Wegovy causes side effects that can cause discomfort, or in rare cases more serious complications. To reduce the risk of side effects, you should always take Wegovy exactly as prescribed by your doctor.

Mild side effects may be improved by:

  • eating smaller portions, and stopping when you feel full
  • eating bland and low-fat foods
  • increasing the amount of fibre in your diet
  • drinking more water

If you are getting side effects that you cannot manage or tolerate, speak to your doctor. It may be that a lower dosage of Wegovy would be more suitable for you, or another weight loss medication could be a better option.

Conclusion: Is the Wegovy pen right for me?

Wegovy is a highly effective weight loss treatment for most people. It is tolerated well by over 80% of people, and can lead to one of the highest amounts of weight loss of all the common weight loss medications available in the UK. However, some people may find injections uncomfortable, or find that Wegovy is not suitable for them. In this case, there are other weight loss treatments that may be a better option for you.

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Frequently asked questions

What is the actual cost of Wegovy?

A one month’s supply of Wegovy costs from £139 with ZAVA online doctor.

How do I get a prescription for Wegovy?

Getting a prescription online with ZAVA online doctor is quick and convenient. You just have to complete a short online questionnaire about your health, which will be assessed by our team of doctors within 24 hours. If it is safe and appropriate for you to be prescribed Wegovy, you will get confirmation and your medication will be delivered to an address of your choice.

Does Wegovy cause depression?

In 2023, concerns were raised that suicidal thoughts might be one of the Wegovy side effects. Newer studies did not confirm these fears and even found evidence that the medicine reduced the risk compared with other medication for diabetes and obesity.

What foods to avoid while taking Wegovy (semaglutide)?

It is recommended to avoid sugary and high fat foods when taking Wegovy. These foods can make it harder to lose weight, and can also increase the risks of gastrointestinal side effects.

Do you gain weight back after using Wegovy?

If you stop using Wegovy, one of the most common effects is weight gain. This isn’t because stopping Wegovy necessarily causes you to gain weight, but you will no longer be affected by the medication, so your appetite will return to normal. You may find that with an increased appetite you need to eat more food to feel full, and gain weight again. To avoid this, make sure you stick to your diet and exercise plan after stopping Wegovy.

How common is hair loss with Wegovy?

The risk of hair loss when taking Wegovy is low. Hair loss is not a reported side effect of Wegovy in the patient information leaflet distributed with the medication, but has been reported in clinical trials. 3% of patients reported hair loss in clinical trials, compared to 1% of those taking a placebo.

Is Wegovy available on the NHS?

Yes, Wegovy is available on the NHS. To get a prescription on the NHS you will need to make an appointment with your GP, who will then refer you on to a weight management specialist. If they determine you are sufficiently at risk, they may prescribe Wegovy for you.

Medically reviewed by:
Dr Babak Ashrafi Clinical Lead for Service Expansion
Accreditations: BSc, MBBS, MRCGP (2008)

Babak studied medicine at King’s College London and graduated in 2003, having also gained a bachelor’s degree in Physiology during his time there. He completed his general practice (GP) training in East London, where he worked for a number of years as a partner at a large inner-city GP practice. He completed the Royal College of GPs membership exam in 2007.

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Last reviewed: 05 Feb 2024

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