Lose Weight with Medication: Medical Treatment for Weight Loss

How does medical weight loss treatment (GLP-1) work in the body?

Modern weight loss medicines, known as GLP-1 receptor agonists, work by mimicking the effects of the body’s natural fullness hormones. This helps slow stomach emptying and sends fullness signals to the brain, which may help you feel satisfied sooner and reduce portion sizes more easily.

The hormone GLP-1 (glucagon-like peptide-1) is naturally released from the gut after meals and plays an important role in appetite regulation and blood sugar control. The treatment also affects the brain’s hunger and fullness regulation. For many people, this can reduce food cravings and constant thoughts about food. This biological support may make it easier to maintain the lifestyle changes and calorie deficit needed for sustainable weight loss.

Examples of medicines in this treatment group include semaglutide (Wegovy) and tirzepatide (Mounjaro), both of which have shown strong results in clinical studies for the treatment of overweight and obesity.

Who may be eligible for medical weight loss treatment?

Medical treatment for weight loss may be suitable for people living with obesity (BMI over 30), or for people living with overweight (BMI over 27) together with at least one weight-related health condition such as type 2 diabetes, high blood pressure, or raised cholesterol.

Treatment may be an option for people who need support to achieve and maintain a healthier weight, especially when previous lifestyle changes have not led to sufficient results.

Assessment is based on current clinical guidelines for the treatment of overweight and obesity. Weight loss medicines are prescribed following an individual medical assessment by a licensed doctor, taking into account factors such as medical history, possible risk factors, ongoing treatments, and relevant test results.

The foundation of treatment is sustainable long-term habits around food and physical activity. Medicines are used as medical support to help with weight loss and reduce the risk of weight regain over time.

What are the most common side effects?

The most common side effects of weight loss medicines are related to the digestive system and mainly include nausea, diarrhoea, constipation, vomiting, and sometimes 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 most people, symptoms improve gradually as the body adapts to treatment.

Many side effects can be eased by eating smaller portions, eating slowly, chewing food thoroughly, and avoiding fatty or heavily spiced foods. Gradually increasing the dose also helps improve tolerability.

If side effects are persistent or severe, it’s important to contact your doctor for an individual assessment and possible adjustment of treatment.

Why aren’t medicines alone enough for long-term results?

Weight loss medicines tend to give the best and most sustainable results when combined with long-term lifestyle changes related to food, physical activity, and behaviour change. The medicines may help increase fullness and reduce hunger, but they do not replace the need for sustainable habits over time.

With rapid weight loss, there is a risk of losing muscle mass, especially if treatment is not combined with enough protein and regular physical activity, including strength training. Muscle mass is important for the body’s function, metabolism, and energy use, and losing it may make long-term weight stability more difficult.

That’s why current medical guidelines recommend combining medication with personalised support around nutrition, physical activity, and lifestyle habits. The goal is not only weight loss, but also improved metabolic health and a lower risk of conditions such as type 2 diabetes and cardiovascular disease.

Frequently asked questions about medical weight loss

Will I get weight loss medication prescribed immediately if I ask for it?

No. Weight loss medicines are only prescribed following an individual medical assessment by a licensed doctor. The assessment is based on factors including your health questionnaire, medical history, possible risk factors, and relevant test results, in line with current medical guidelines for the treatment of overweight and obesity.

The treating doctor will always decide whether medication is medically appropriate for you.

Do I need to stay on medication for life to maintain the weight loss?

Obesity is a chronic condition where the body’s biological mechanisms may work against long-term weight loss. After losing weight, hunger regulation, energy expenditure, and hormonal signals can change in a way that increases the risk of regaining weight, a phenomenon sometimes referred to as metabolic adaptation.

For some people, longer-term or ongoing treatment may therefore be appropriate to help maintain results over time. However, the need for continued treatment varies between individuals and is regularly reviewed together with your doctor based on treatment response, overall health, and personal goals.

How much weight do people lose on average with treatment?

Clinical studies show that modern weight loss medicines such as semaglutide and tirzepatide can lead to significant weight loss when treatment is combined with lifestyle changes related to food and physical activity. On average, studies have shown weight loss of around 15 to 20% of body weight over approximately 12 to 18 months.

Results vary between individuals and are influenced by factors such as biology, adherence to treatment, lifestyle habits, and any existing health conditions. The aim of treatment is not only weight loss, but also improved metabolic health and a lower risk of health conditions linked to overweight and obesity.

Can you take weight loss medication during pregnancy?

No. Weight loss medicines should not be used during pregnancy or breastfeeding, as safety for the unborn baby and breastfed child has not been sufficiently established. Treatment should therefore be stopped well in advance of a planned pregnancy, together with guidance from your doctor.

How long before pregnancy treatment should be paused depends on the medicine being used, as different medicines remain in the body for different lengths of time. It’s important to discuss pregnancy planning with your healthcare provider before starting or stopping treatment.

Does the medication negatively affect muscle mass?

With any weight loss, there is a risk of losing some muscle mass, regardless of whether the weight loss happens through lifestyle changes, medication, or surgery. There is currently no evidence suggesting that GLP-1-based medicines directly break down muscle tissue, but because body weight decreases, some muscle loss may occur if treatment is not combined with appropriate nutrition and physical activity.

That’s why adequate protein intake and regular strength training are recommended to help maintain muscle mass, strength, and metabolism during treatment. The goal is mainly to reduce body fat while preserving the body’s function and muscle mass as much as possible.