Therapy with semaglutide (Ozempic or Wegovy) and tirzepatide (Mounjaro) in the context of obesity - Update 2025

Introduction

Obesity is one of the greatest health challenges of our time. According to the Robert Koch Institute (RKI), over 50% of adults in Germany are overweight, of which around 23% are obese (BMI ≥30 kg/m²). There has also been a significant increase in children and adolescents: Around 15% are overweight and around 6% are obese - and the trend is rising.with a rising trend.

Obesity is more than just a cosmetic problem. It is a chronic, multifactorial risk factor for numerous secondary diseases, including:

• Type 2 diabetes mellitus
• High blood pressure and cardiovascular diseases
• Sleep apnea
• Joint pain and osteoarthritis
• Fatty liver disease (NAFLD/NASH)
• Certain types of tumors (e.g.breast, intestinal, pancreatic tumorsüpancreatic cancer)

The life expectancy of severely obese people is significantly reduced - by up to 10 years, depending on comorbidities. At the same time, many of those affected experience a loss of quality of life, mobility and socialparticipation.

Despite broad awareness campaigns and prevention strategies, it is often not enough to achieve sustainable weight loss through lifestyle changes alone (diet, exercise, behavior). This is where modern pharmacological therapies such as semaglutide and tirzepatide come in.

semaglutide (Ozempic, Wegovy) belongs to the group of GLP-1 receptor agonists and was originally developed for the treatment of type 2 diabetes. It has now also proven its worth in obesity therapy.
Another further innovative drug with even greater efficacy is tirzepatide (Mounjaro), which has been approved in Europe for the treatment of type 2 diabetes since 2024 and for weight reduction in obesity since 2025. It represents a new generation of metabolic therapy - with a dual mode of action.

Indications & practical tips

• Both substances are suitable for patients with obesity(BMI ≥ 30) or overweight(BMI ≥ 27 + concomitant diseases) suitable.
• Important: They do not replace lifestyle changes, but reinforce their effect.
• Both therapies should be accompanied by nutritional advice, exercise promotion and, if necessary, psychological support if necessary.

Mechanism of action of semaglutide (Ozempic/Wegovy)

Semaglutide acts via the GLP-1 receptor. It:

• Increased insulin secretion with simultaneously reduced glucagon release - but glucose-dependent, which reduces the risk of hypoglycaemia.
• Lowers the release of glucagon
• Delayed gastric emptyingwhich means that the feeling of fullness sets in earlier and lasts longer.
• Central effect in the hypothalamuswhich leads to a significant reduction in appetite.
  These multimodal effects not only influencenot only the glucose metabolism, but also lead to a significant reduction in body weight.

Dosage and application

Semaglutide (Ozempic® / Wegovy®)

• Application: Subcutaneous injection once a week - preferably in the abdomen, thigh or upper arm. Injection sites should be changed regularly.
• Wegovy®:
  • Starting dose: 0.25 mg/week
  • Slow increase over 16 weeks to the target dose of 2.4 mg/week to minimize side effects such as nausea.
• Ozempic®:
  • Primarily used for blood sugarcontrol, but also off-label for weight reduction.
  • Available in doses up to 2.0 mg/week

New in focus: Tirzepatide (Mounjaro)

What is Mounjaro?

Tirzepatide is a so-called dual-agonistic incretin mimeticthat two receptors simultaneously:

• GLP-1 (glucagon-like peptide-1)
• GIP (glucose-dependent insulinotropic polypeptide)

This combination leads to:

• stronger appetite regulation,
• more intense feeling of satiety,
• faster and greater weight loss,
• and better blood glucose controle than GLP-1 monopreparations.

How does tirzepatide work?

• GLP-1 component has the same effect as semaglutide: increases the release of insulin, delays gastric emptying and reduces appetite.
• GIP component enhances insulin action in peripheral tissues and favorably modulates adipose tissue and inflammation.
• There are indications of a positive effect on fatty liver (NAFLD/NASH) and the cardiometabolic and the cardiometabolic profile.

Current study data (SURMOUNT-1 to 4)

In clinical trials for obesity treatment without diabetes (SURMOUNT-1 & 2):

• Weight reduction of more than 20 % of body weight with 15 mg tirzepatide weekly.
• Significantly higher than with semaglutide (15-18%).
• Improvements were also seen in blood lipid levels, blood pressure, insulin resistance and inflammation parameters.
• Initial data also indicate a reduction in cardiovascular events in non-diabetics.

Dosage and administration of tirzepatide (Mounjaro)

• Application: Also once a week subcutaneously, analogous to semaglutide. Here, too, you can vary between abdomen, thigh or upper arm.
• Starting dose: 2.5 mg/week for 4 weeks.
• Then gradually increase the dose in 2.5 mg increments up to the target dose of up to 15 mg/week (depending on tolerability and therapeutic success).
• Full effectiveness in terms of weight reduction is usually achieved from 10 mg, with 15 mg being the highest approved dose.
• Important: Slow dosing to avoid side effects.side effects.

Side effects

• Similar to GLP-1 analogs: nausea, diarrhea, feeling of fullness.
• Low risk of hypoglycemia with monotherapy.
• Possible interactions with other medications due to delayed gastric emptying.

Comparison: Semaglutide vs. tirzepatide