GLP-1: How Medical Weight Loss Works

What is GLP-1?

GLP-1 (glucagon-like peptide-1) is a natural hormone released from the gut after eating. It helps regulate appetite, fullness, and blood sugar levels. Today, GLP-1-based medicines are used to treat obesity and type 2 diabetes.

These medicines work by mimicking the body’s own GLP-1 hormone, but with a longer-lasting effect. This strengthens fullness signals, reduces hunger, and influences appetite regulation for a longer period of time.

Examples of medicines in this treatment group include semaglutide (Wegovy and Ozempic) and tirzepatide (Mounjaro). In clinical studies, these treatments have shown good results in the treatment of overweight and obesity.

How does GLP-1 work?

GLP-1-based medicines affect the body’s systems involved in hunger, fullness, and blood sugar regulation. The treatment slows stomach emptying and affects the brain’s appetite centre, which may help reduce hunger, increase feelings of fullness, and reduce food cravings. Over time, this can make it easier to maintain a lower calorie intake.

At the same time, the treatment helps support more stable blood sugar regulation by stimulating insulin release when blood sugar levels rise. This can reduce blood sugar fluctuations and is one of the reasons GLP-1 medicines are also used to treat type 2 diabetes.

Together, these effects may create better conditions for sustainable weight loss and improved metabolic health.

Who can get GLP-1 treatment?

GLP-1-based medicines may be suitable for people living with obesity (BMI over 30), or for people living with overweight (BMI over 27) alongside weight-related health conditions such as high blood pressure, type 2 diabetes, or raised cholesterol.

Obesity is now classified as a chronic condition, and treatment aims to reduce the risk of serious health problems linked to excess weight. These medicines are therefore not intended for cosmetic weight loss in people with a healthy weight.

Treatment is always preceded by an individual medical assessment carried out by a licensed doctor. This assessment considers factors such as medical history, previous treatment attempts, possible risk factors, and relevant test results to determine whether treatment is medically appropriate based on the person’s health.

How is GLP-1 treatment taken?

GLP-1-based medicines are usually given as an injection under the skin once a week, most often in the stomach, thigh, or upper arm. Treatment begins with a low dose that is gradually increased so the body can adjust and to help reduce the risk of side effects.

The medicines are administered using pre-filled injection pens designed to be easy to use at home. The needle is very thin, and many people find the injection relatively painless.

There are also GLP-1 medicines available in tablet form, such as Rybelsus, which contains the active ingredient semaglutide. Dosage and treatment plans vary depending on the medicine, treatment goals, and individual medical needs.

Weight loss results with GLP-1 according to studies

Clinical studies show that modern GLP-1-based medicines can lead to significant weight loss in the treatment of overweight and obesity. On average, people treated with semaglutide or tirzepatide have achieved weight loss of around 15 to 20% of their body weight over approximately 12 to 18 months of treatment, combined with lifestyle changes. Results vary between individuals and are influenced by factors such as biology, treatment adherence, physical activity, and eating habits.

Side effects of GLP-1 medicines

The most common side effects with GLP-1-based medicines are related to the digestive system and mainly include nausea, diarrhoea, constipation, and sometimes vomiting or stomach discomfort. Symptoms are usually mild to moderate and happen mainly at the start of treatment or when the dose is increased.

These side effects are an expected result of how the medicines work, as they slow stomach emptying and affect appetite regulation. For many people, symptoms improve gradually as the body adapts to treatment. Eating smaller portions and avoiding large or fatty meals may help reduce symptoms.

Less common but more serious side effects can occur, including gallbladder problems or inflammation of the pancreas (pancreatitis). Because of this, it’s important that treatment is monitored by a doctor and that any new or persistent symptoms are medically assessed.

Frequently asked questions about weight loss with GLP-1

Do you need to take GLP-1 medication for life?

Obesity is a chronic condition where the body’s biological systems often work against long-term weight loss. If treatment is stopped, hunger, appetite, and weight regain may return over time, meaning some people may need long-term treatment to maintain results.

The need for continued treatment varies from person to person and is assessed together with your doctor. For some people, a lower maintenance dose may be an option, especially alongside sustainable habits around food and physical activity.

Do you need type 2 diabetes to get GLP-1 treatment?

No. GLP-1-based medicines are used both for the treatment of type 2 diabetes and for the treatment of overweight and obesity. For weight management, treatment may be suitable for people living with obesity (BMI over 30), or for people living with overweight (BMI over 27) together with weight-related health conditions such as high blood pressure or type 2 diabetes.

These medicines are prescribed following an individual medical assessment by a licensed doctor, based on the person’s health and current clinical guidelines.

Is GLP-1 available as tablets or only injections?

Yes. GLP-1-based medicines are available both as injections and in tablet form. The active ingredient semaglutide is available, for example, as a daily tablet called Rybelsus.

Rybelsus is currently approved in the UK for the treatment of type 2 diabetes, but in some cases it may be prescribed off-label for overweight and obesity following an individual medical assessment by a doctor. The most suitable treatment option depends on the person’s health, treatment goals, and medical circumstances.

Can you drink alcohol during treatment?

Yes, but alcohol should be consumed with caution while taking GLP-1-based medicines. Because stomach emptying is slowed, alcohol may affect the body differently than before, and some people may notice increased sensitivity to alcohol or become intoxicated more quickly.

Alcohol can also worsen common side effects such as nausea, stomach pain, and dizziness. Tolerance varies between individuals, so it’s important to pay attention to how your body responds during treatment.