Wegovy (semaglutide) and Orlistat are both medicines used for weight loss for those who are overweight or obese. Both are registered in the UK for chronic weight management (the treatment of obesity) in conjunction with diet and exercise leaving many wondering, what exactly is the difference between Wegovy and Orlistat and which is best to help you lose weight?

There are a number of key differences between the treatments such as dose form, administration, how they work, effectiveness and potential side effects.

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The differences between Wegovy vs Orlistat

Dose form and administration

The first major difference is the form of each medicine and how they are used.

Wegovy comes in an injection pen, similar to Saxenda and insulin. It is injected ONCE WEEKLY into the fat layer just under the skin with a tiny 4-8mm needle. The dose is started low and is progressively increased over 5 months as your body adjusts to the medicine.

Orlistat comes in hard capsules which are taken with or up to 1 hour after eating your 3 main meals. Unlike Wegovy, Orlistat is taken at a steady dose of 120mg for prescription-strength Orlistat (Xenical or Generic) or 60mg for the over the counter strength of Orlistat called Alli.

The differences in how they work

Although they are both obesity medications intended to be used alongside diet and exercise, the way Wegovy and Orlistat work is vastly different.

Wegovy contains the GLP-1 analogue semaglutide. This medicine works as an appetite suppressant by mimicking the effect of a naturally occurring hormone in the body that regulates how hungry you feel. In doing this, it allows you to feel less hungry after smaller meals, making it significantly easier to eat less throughout the day. This decreases the number of calories you take in, helping you to eat fewer calories than you use, causing weight loss.

Orlistat works quite differently. It causes your body to absorb up to 33% less fat from your meals. Even healthy foods can have some fats which contribute to your daily calorie intake, decreasing them by a third helps to keep your absorbed calories lower than what you burn each day, assisting with weight loss. It also acts as a form of deterrent to eating high-fat meals as it can result in gastric upset.

The differences in effectiveness

Both studies have been through numerous clinical trials evaluating the effectiveness of the medicines for treating obesity. Both have results considered strong enough by UK medicines regulators to be considered effective weight loss medicines.

Below is a look at both medicines in 2 separate studies vs placebo groups. Please note that these studies were for similar, but not the same, treatment duration. 

Wegovy effectiveness over 68-week study

Wegovy Effectiveness Chart


Source: Wegovy efficacy and safety trails

Orlistat effectiveness over 1 year of treatment

Orlistat Study Results

Wegovy and Orlistat’s similarities

Both medicines are used in patients with a body mass index (BMI) of over 30kg/m² or 27kg/m² with underlying health conditions such as high cholesterol, high blood pressure or chronic weight-related conditions. Each needs to be used in conjunction with a balanced reduced-calorie diet and exercise to improve the speed and quality of the results.

The goal of each weight loss treatment is to reduce your BMI to a point where you feel comfortable enough to come off the medicine and continue maintaining your healthy weight with a balanced diet.

In terms of side effects, they are both similar in the type of side effects they can cause. Predominately some people may experience gastric upset such as nausea, vomiting and diarrhoea. Orlistat is highly likely to cause loose bowel motions when taken with high-fat meals. Wegovy however is more likely to cause nausea however this can be managed by slowly increasing the dose and usually resolves with continued use.

About Wegovy

Wegovy is a recently approved medicine for weight loss in the UK, gaining its registration in early 2022. It came from the same company which created liraglutide (Saxenda), Novo Nordisk.

Wegovy’s active ingredient semaglutide has long been used for diabetes treatment (Ozempic), however, it was noticed that it had a positive effect on appetite control for those using it. Taking full advantage of these positive results, the company began trials to find the optimal dosing schedule for weight loss now used with Wegovy.

Wegovy is scheduled to be released in the UK in the first half of 2022. It will become available from our online weight loss clinic as soon as possible. To be notified upon its release, you can register for notification with us.

Order Wegovy from £149

About Orlistat


Orlistat is a weight loss capsule currently available in the UK over the counter or on prescription. Since its approval in 1999 by the food and drug administration, Orlistat quickly became and remained a popular weight loss option due to how simple it is to use and its effectiveness in clinical trials.

Take an assessment and order Orlistat today from £17.50


Wegovy vs Orlistat Summary


Wegovy and Orlistat have a number of differences including how they are used, how they work and their effectiveness however they both remain effective options for losing weight. Which one is right for you may vary based on your current health and preferences. You may consult our doctors with an online assessment for free from our medicine pages or you can consult your own GP about these treatments to see if one is suitable for you.


Prescription weight loss treatments available today