Ozempic (semaglutide) for the treatment of obesity

What is Ozempic (semaglutide)?

Ozempic contains the active substance semaglutide, which belongs to the drug class known as GLP-1 receptor agonists. It works by mimicking the effect of the body's own intestinal hormone GLP-1 (glucagon-like peptide-1), which is involved in the regulation of appetite and blood sugar.

When food is consumed, GLP-1 is naturally released from the small intestine and signals to the brain that the body has been supplied with energy. However, the hormone has a short half-life and is rapidly broken down in the body. Semaglutide is structurally modified to resist this breakdown, providing a more long-lasting effect.

The treatment affects several mechanisms in the body. It contributes to improved blood sugar control by stimulating insulin release in a glucose-dependent manner, while simultaneously reducing appetite and increasing the feeling of fullness. Additionally, gastric emptying is delayed. Taken together, all these effects can contribute to a reduced energy intake.

Ozempic is approved for the treatment of type 2 diabetes. In certain cases, the medication may be prescribed outside of the approved indication (off-label), for example, in the treatment of overweight, following an individual medical assessment.

Dosing Ozempic (as a solution in a pre-filled injection pen)

Ozempic is administered once a week as a subcutaneous injection using a pre-filled injection pen. The pen is designed to be easy to use, making it possible to administer the treatment at home after instruction from a healthcare provider.

The medication is injected into the subcutaneous fat (subcutaneously), usually in the abdomen, the front of the thighs, or the back of the upper arm. It is recommended to rotate the injection site between doses to reduce the risk of local skin irritation.

To maintain a steady level of the medication in the body, the injection should be taken on the same day every week.

Before injection, it is important to check the solution through the pen's window. The liquid should be clear and colorless. If it is cloudy or contains particles, the pen should not be used.

How a pre-filled injection pen works in practice

A pre-filled injection pen is a medical device designed to make it simple and safe to administer a preset dose of medication. The medication is injected via a very thin needle, which means the prick is usually experienced as mild or barely noticeable.

To set the correct amount of medication, the pen uses a click system. You turn the pen's dose selector until the correct dose is shown in the dose window.

When the needle is inserted into the skin and the injection button is pressed, the mechanism that delivers the set amount of medication is activated. Ensure the dose counter returns to 0.

It is important to keep the injection button pressed down and let the needle remain in the skin for at least about 6 seconds after the dose counter has returned to zero. This reduces the risk of a small amount of medication leaking out and ensures that the entire dose is administered correctly.

Dosage and Escalation

Treatment with semaglutide (e.g., Ozempic) begins with a low starting dose, usually 0.25 mg once a week, which can thereafter be adjusted stepwise based on individual tolerance and treatment response.

The gradual dose escalation primarily aims to reduce the risk of gastrointestinal-related side effects, such as nausea. Usually, each dose level is maintained for at least four weeks before a potential dose adjustment is considered in consultation with the treating physician.

In clinical practice, the principle of the lowest effective dose is often applied, meaning the treatment is adapted to the lowest dose that provides sufficient effect with acceptable tolerability. Therefore, not all patients need to reach the highest possible dose.

In clinical studies, different dose levels have been evaluated depending on the indication:

• In the treatment of type 2 diabetes (Ozempic), doses up to 1.0 mg and 2.0 mg once a week have been studied and approved for blood sugar control.
• In the treatment of obesity (Wegovy), higher doses of semaglutide, up to 2.4 mg once a week, have been used in studies (the STEP program), where these doses showed a greater average effect on weight loss.

The choice of dose and preparation is always based on treatment goals, efficacy, side effects, and individual circumstances.

Ozempic for weight loss

The effect of semaglutide on weight loss is influenced both by the dose level and by the patient population being treated.

In clinical studies on patients with type 2 diabetes (e.g., the SUSTAIN program), where semaglutide was used in doses up to 1.0–2.0 mg per week, an average weight loss of approximately 5–10 percent of body weight was observed.

In studies on people with obesity without concurrent diabetes (e.g., the STEP program), where higher doses of semaglutide (2.4 mg per week) were used, an average weight loss of around 15 percent was reported after approximately 68 weeks of treatment.

Who can be prescribed Ozempic?

Ozempic is a prescription medication approved for the treatment of type 2 diabetes. Prescription occurs after an individual medical assessment by a licensed physician, where consideration is given to, among other things, blood sugar control, comorbidities, and previous treatments.

In the treatment of overweight and obesity, medications specifically approved for this purpose are primarily used. Generally, pharmacological treatment of obesity can be considered at a BMI ≥30, or at a BMI ≥27 in combination with at least one weight-related complication, such as hypertension, dyslipidemia, or obstructive sleep apnea.

Prescribing Ozempic solely for the purpose of achieving weight loss constitutes use outside of the approved indication (off-label) and may in certain cases be considered after an individual medical assessment.

Prior to treatment, the physician makes a comprehensive assessment that includes medical history, current medications, and relevant laboratory tests to ensure that the treatment is medically appropriate and safe.

Common side effects of medical treatment

The most common side effects of treatment with medications containing semaglutide are gastrointestinal and include nausea, diarrhea, constipation, and sometimes vomiting. These symptoms are usually mild to moderate and tend to subside as the body adapts to the treatment.

Since the medication delays gastric emptying, it is expected that the gastrointestinal tract will be affected, especially at the beginning of treatment or in connection with a dose increase. The discomfort is often most pronounced during the first few days after a dose adjustment.

Symptoms can often be alleviated through simple daily measures, such as:

• Eating smaller and more frequent meals
• Chewing food thoroughly
• Limiting the intake of fatty, fried, or highly spiced food, as such a diet can be harder to digest

Read our guide on side effects for more practical advice and recommendations.

The risk of muscle loss during rapid weight loss

During weight loss, regardless of the method, there is often some loss of both fat mass and muscle mass. During rapid weight loss, including treatment with medications like semaglutide (e.g., Ozempic), the proportion of muscle mass lost can increase if no counter-measures are taken.

Loss of muscle mass can, in the long term, affect basal energy expenditure (resting metabolic rate), which can make it more challenging to maintain a lower body weight over time.

To promote a more favorable body composition — where a larger proportion of the weight loss consists of fat mass — the following is recommended:

• An adequate protein intake, distributed across the day's meals
• Regular strength training or other weight-bearing physical activity

These measures contribute to preserving muscle mass during weight loss and thus support both metabolic health and long-term weight stability.

Read more about this in our guides on protein and weight loss and strength training during weight loss.

Facts about Novo Nordisk and the difference from Wegovy

Both Ozempic and Wegovy are manufactured by the Danish pharmaceutical company Novo Nordisk and contain the same active substance, semaglutide. However, the medications differ regarding approved indication, dosage, and treatment goals.

Ozempic was developed and approved for the treatment of type 2 diabetes, with the aim of improving blood sugar control. Wegovy, on the other hand, is specifically designed and approved for the treatment of obesity and overweight in combination with weight-related complications, and is dose-adjusted for this purpose.

In the treatment of patients without type 2 diabetes, where the main indication is weight loss, medications approved for obesity treatment are generally the first choice. Prescribing Ozempic solely for the purpose of achieving weight loss constitutes use outside of the approved indication (off-label) and requires an individual medical assessment.

You can read more about the similarities and differences between the preparations in our in-depth comparison article.

Frequently Asked Questions about Ozempic

Does it hurt to take the injection?

Most patients experience the injection as very minimally painful or, in practice, virtually painless. The needle is very thin and short, and the medication is administered superficially into the subcutaneous fat, which generally causes limited discomfort. However, the experience can vary between individuals, and some may feel a brief prick or light stinging in connection with the injection.

What happens if I forget to take my dose?

If you forget a dose, you can take it as soon as you remember, provided it has been less than 5 days since it should have been taken. If more than 5 days have passed, skip the missed dose and take the next injection on your usual scheduled day.

How do I store the pen?

An unopened pen should always be stored in the refrigerator (2°C to 8°C). After the pen has been opened and used for the first time, it can be stored at room temperature (below 30°C) or in the refrigerator for up to 6 weeks.

References

European Medicines Agency. Ozempic : EPAR – summary for the public. https://www.ema.europa.eu/en/medicines/human/EPAR/ozempic

Wilding JPH et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). The New England Journal of Medicine. https://www.nejm.org/doi/full/10.1056/NEJMoa2032183

Bergmann, N. C. et al. Semaglutide for the treatment of overweight and obesity: A review. Diabetes, Obesity and Metabolism, 25(1), 18–35. https://doi.org/10.1111/dom.14863

Konstantinos C et al. Obesity and cardiovascular disease: an ESC clinical consensus statement. European Heart Journal. 2024;45(38):4063–4098. https://doi.org/10.1093/eurheartj/ehae508

World Health Organization (WHO). WHO Guidelines on Physical Activity and Sedentary Behaviour. Geneva: World Health Organization; 2020. https://www.who.int/publications/i/item/9789240015128