What is Wegovy, Ozempic and Rybelsus?
Wegovy is a weekly injection for long-term weight management and contains the active ingredient semaglutide. It is made by the same company as Ozempic and Rybelsus (Novo Nordisk) – the difference being that Wegovy is designed for weight control, while Ozempic and Rybelsus are meant for people with type 2 diabetes.
How do these medications work?
Your body naturally produces an appetite hormone called glucagon-like peptide 1 (GLP-1), this helps regulate your hunger, keeps you feeling fuller and helps control those nagging food cravings. These medications work because their active ingredient, semaglutide, is a GLP-1 receptor agonist – this means it has the same appetite-controlling effects on the body. As a result, it regulates your hunger so you eat fewer calories, slows stomach emptying so you stay full for longer and turns off the messages in your head that make you seek out certain foods.
Do weight loss drugs work?
Clinical trials indicate that when used alongside a balanced diet, increased physical activity and behavioural support, Wegovy can help users achieve as much as a 15 per cent reduction in body weight after one year.
Similarly, studies suggest Ozempic significantly improves blood sugar management as well as weight; while in overweight and obese adults 50mg of semaglutide, taken orally also leads to a meaningful decrease in bodyweight.
How to get medications containing semaglutide?
Wegovy is licensed for use and available via specialist ‘tier 3’ NHS weight management services on condition you meet the eligibility criteria – these include:
• A BMI of 35 or more or 32.5 for some minority ethnic groups
• You have at least one weight-related disease such as diabetes, heart disease or high blood pressure
• You have tried conventional weight loss methods without success.
Ozempic is prescribed by the NHS to treat type 2 diabetes, not weight loss. To be eligible for a prescription you must be diagnosed with type 2 diabetes, you may be eligible if other treatments, like metformin, have not worked for you or you have poorly controlled diabetes. Rybelsus is also a prescription-only medication licensed for the treatment of type 2 diabetes, however, both Rybelsus and Ozempic are sometimes used unofficially as a weight loss tool.
How to take weight loss medications
Wegovy and Ozempic are injections that are taken once per week. If you are on Wegovy, your doctor will review your progress after six months and if you have lost at least five per cent of your body weight, you will be able to continue the treatment – the NHS currently prescribes this medication for a maximum of two years. In conjunction, you will be encouraged to follow a balanced diet combined with regular movement.
Rybelsus comes in tablet form, you typically take a lower dose for the first 30 days to allow your body to acclimatise and then increase the dose under supervision. The tablet is taken on waking, on an empty stomach and with water, you then need to wait 30 minutes before eating, drinking or taking other medication or supplements.
What are the side effects of these drugs?
Side effects include digestive issues such as nausea, stomach pain, diarrhoea and vomiting.
What is Saxenda?
Saxenda is a daily injection for long-term weight management and contains the active ingredient, liraglutide.
How does Saxenda work?
Like semaglutide, liraglutide is a GLP-1 agonist, and works by regulating your appetite and slowing gastric emptying so you eat less and experience fewer cravings.
Is Saxenda effective?
Combined with lifestyle changes, Saxenda appears to reduce weight and improves blood sugar control, although some studies suggest it may not be as effective as semaglutide.
How to get Saxenda
In the UK, NHS eligibility requires:
• A BMI of 35 or more or 32.5 for some minority ethnic groups
• You have non-diabetic high blood sugar levels (sometimes referred to as pre-diabetes)
• You are at risk of heart attack or stroke because you have high blood pressure or high cholesterol.
How to take Saxenda
Saxenda is injected daily into the skin on your stomach, thigh or upper arm. The dosing starts low in order to help minimise side effects. Your doctor will review progress after three months of use, and if you’ve achieved at least a five per cent weight loss, you’ll be able to continue use. You will also be encouraged to combine lifestyle changes, such as a healthy diet and exercise.
What are the downsides?
Nausea is the most common side effect of this medication.
What is Mounjaro?
Mounjaro is the brand name for tirzepatide, a drug that lowers blood sugar levels.
How does Mounjaro work?
Mounjaro works by mimicking the action of two hormones, GLP-1 and a second called glucose-dependent insulinotropic polypeptide (GIP). The dual effect of the medication is to slow digestion, reduce hunger and combat cravings, as well as to help your body produce more insulin, therefore reducing the amount of glucose produced by the liver. By imitating the GIP hormone, Mounjaro sends signals via the brain to regulate energy balance, help control blood sugar and as a result leads to weight loss.
Is Mounjaro effective?
Numerous studies support Mounjaro’s positive effects for type 2 diabetes – one 72-week study found that when combined with a healthy lifestyle, Mounjaro led to an average 22 per cent weight loss in obese patients who were taking the highest maintenance dose.
How to get Mounjaro
Mounjaro has been approved by the NHS for treating obesity but certain eligibility criteria must be met. These include:
• Have a BMI of 35 or over
• Have at least one weight-related health condition such as hypertension, cardiovascular disease, type 2 diabetes or pre-diabetes.
There are plans for Mounjaro to be prescribed outside of specialist weight management services, however, details for this are still to be released.
How to take Mounjaro
Mounjaro is administered as an injection once per week, patients typically start on a low dose which increases every four weeks until you reach the dose that is appropriate for you.
What are the downsides?
Nausea and diarrhoea are the two most common side effects and may affect one in 10 people. These effects tend to be temporary and typically occur when the dose is changed.
What is orlistat?
Orlistat, sold under the brand names Xenical, Alli and Orlos is an oral weight loss pill which comes in capsule form.
How does orlistat work?
It works by blocking the action of a fat enzyme, this reduces the amount of dietary fat that your body absorbs. As a result, about a third of the fat you eat will pass through the body and be removed via the bowel.
Is orlistat effective?
There is evidence that Xenical, Alli and Orlos may be effective, however, not all people lose weight and if you have not lost five per cent of your body weight after three months, your GP may take the decision to stop this course of treatment.
How to get orlistat
Orlistat is available on prescription in the UK from your GP. To be eligible via the NHS you would need to have made a significant effort to lose weight through conventional methods and have a BMI of 30 or more, or a BMI of 28 combined with a weight-related condition such as high blood pressure or type 2 diabetes.
Orlistat sold as Alli and Orlos offer a lower dose (60mg per dose, compared to 120mg) and are available directly from pharmacies, sold under their supervision.
How to take orlistat
Orlistat should be taken alongside a reduced-calorie diet and combined with regular exercise – these lifestyle changes should start before you begin the medication. You will be advised to take Orlistat immediately before, during or up to one hour after each of your three daily meals. If you miss a meal or the meal is very low in fat, you should skip your dose.
What are the downsides?
The most common side effects of orlistat include fatty or oily faeces, with an increased frequency and urgency to go. You may also experience more wind as well as nausea.
Weight-loss drugs: dangers and risks
Weight loss injections are not available over the counter because of their active ingredients, so you will need a prescription. If you do not meet the NHS prescribing criteria, you may be able to access the medication with a private prescription, however be sure to get a full assessment as well as ongoing support from a qualified prescribing healthcare professional. Of the medications listed above, only Orlistat, as Alli or Orlos, is available over the counter from pharmacists.
Purchasing these medications without a prescription, from illegal suppliers, increases your risk of receiving unlicensed or counterfeit products. Weight loss medications from other sources are both illegal and may lead to serious side effects. This is because these medications may not contain the ingredients they claim, for example, some false products purchased in the UK as Saxenda and Ozempic actually contained insulin and not semaglutide. Use of these products resulted in hospitalisation and, in some cases, hypoglycaemic shock and coma.
Medication in the form of GLP-1 agonists are relatively new and some, such as Ozempic, are classed as a ‘black triangle medicine’. This means even as the licensed product, it is subject to increased monitoring and reporting, via the Yellow Card scheme.
As well as the common digestive side effects, some people experience pancreatitis, gallstones and an increased heart rate. Although there are also reports of some cardioprotective effects while taking this type of medication.
As a long-term weight solution these medications may be limited, this is because the NHS currently prescribes for a maximum of two years only, and weight typically returns when the medication is stopped.
Who should not take these medications?
These medications are unsuitable for those with a history of thyroid cancer, pancreatitis or gallbladder disease. Speak to your healthcare professional if you are pregnant, planning a pregnancy or breastfeeding. Weight loss medication may not be suitable for those who are under 12 and over 75 years.
So, are weight loss drugs the answer?
Evidence suggests that certain medications may help with obesity, but they are not a magic bullet and no one drug works for everyone. That said for some people these medications may be the trigger that helps them implement healthier behaviours, such as increased activity, and improved food choices and portion sizes. However, in the UK these medications are not available to everyone, making conventional weight loss methods the only option for the majority.
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This article was updated by Kerry Torrens in January 2025.
Kerry Torrens BSc. (Hons) PgCert MBANT is a registered nutritionist with a post-graduate diploma in Personalised Nutrition & Nutritional Therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications including Good Food.
All health content on goodfood.com is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional. If you have any concerns about your general health, you should contact your local health care provider. See our website terms and conditions for more information.
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