Pharmacological Obesity Therapy with GLP-1 Receptor Agonists
Since 2022, GLP-1 receptor agonists have fundamentally changed obesity therapy. Active ingredients such as semaglutide and tirzepatide achieve average weight loss of 15-22% of body weight in clinical studies[1,2] — a result previously only possible through bariatric surgery.
In our practice, we offer physician-guided GLP-1 therapy as part of a multimodal approach: medication alone is not sufficient. The combination with dietary modifications, physical activity, and regular diagnostics determines long-term success.
How GLP-1 Receptor Agonists Work
GLP-1 (Glucagon-like Peptide-1) is a naturally produced intestinal hormone released after eating. It regulates blood glucose, slows gastric emptying, and signals satiety to the brain. GLP-1 receptor agonists enhance this mechanism:
- Central Satiety Effect: Reduction of hunger and appetite via hypothalamic receptors — not a matter of willpower, but neurobiology.
- Slowed Gastric Emptying: Prolonged satiety feeling after meals.
- Blood Glucose Regulation: Glucose-dependent insulin secretion — particularly relevant in accompanying type 2 diabetes or insulin resistance.
- Cardiovascular Protection: Proven reduction of major cardiovascular events (MACE) in long-term studies (SELECT study).[3]
Available Active Ingredients
Semaglutide
Once-weekly subcutaneous injection. Gradual dose escalation over 16 weeks to a target dose of 2.4 mg. In the STEP-1 study, patients achieved an average weight loss of approximately 15% after 68 weeks.[1]
Approved for weight loss with BMI ≥ 30 or BMI ≥ 27 with comorbidity.
Tirzepatide
Dual GIP/GLP-1 receptor agonist, also once-weekly subcutaneous injection. Tirzepatide additionally activates the GIP receptor and achieves average weight loss of over 20% in the SURMOUNT-1 study.[2]
Particularly promising in patients with sleep apnea: the SURMOUNT-OSA study showed an AHI reduction of approximately 50%.[4]
For Whom is the Therapy Suitable?
Pharmacological obesity therapy is indicated when lifestyle measures alone are insufficient. The S3 Guidelines on Obesity (AWMF 050-001, 2024) recommend consideration of pharmacological options in:
- BMI ≥ 30 kg/m² after at least 6 months of structured lifestyle intervention without adequate success
- BMI ≥ 27 kg/m² with weight-related comorbidities (type 2 diabetes, hypertension, sleep apnea, MASLD)
- Patients with high cardiovascular risk where weight loss is prognostically relevant
What the Therapy Includes at Our Practice
GLP-1 agonists are not self-running. We support you with a structured program:
- Initial Consultation and Indication Assessment: Comprehensive history, laboratory diagnostics, BIA measurement of body composition, evaluation of comorbidities and contraindications.
- Dose Escalation Phase: Gradual dose increases with regular follow-up consultations, side effect management (particularly gastrointestinal in the first weeks).
- Dietary Adaptation: Under GLP-1 therapy, most people eat significantly less — so it's crucial that the right food is on the plate. Adequate protein protects muscle mass.
- BIA Follow-up Measurements: Approximately every three months measuring body composition to ensure fat mass is being lost — not muscle mass.
- Laboratory Monitoring: Regular checks of blood glucose, HbA1c, liver and kidney function, thyroid, lipid profile.
- Sleep Diagnostics if Indicated: Many obese patients have undiagnosed sleep apnea. Weight loss with GLP-1 can significantly lower the AHI.
Common Side Effects
The most frequent side effects are gastrointestinal and occur particularly during the dose escalation phase: nausea, constipation, rarely diarrhea. These symptoms are typically mild to moderate and decrease over time. Slow dose escalation and accompanying dietary counseling significantly reduce discomfort.
Rarer but relevant side effects (pancreatitis, gallstone formation, thyroid disease) are detected early through structured monitoring. We discuss all risks before therapy begins.
Any weight loss — with or without medication — involves some loss of muscle mass. Under GLP-1 agonists, this portion can account for 30-40% of total weight loss. Therefore, protein-optimized nutrition (1.2-1.5 g/kg target weight) and regular strength training are essential. BIA follow-up measurement makes it visible whether your muscle is preserved.
GLP-1 receptor agonists for weight loss in obesity without type 2 diabetes are not reimbursable in Germany. Medical guidance — initial consultation, diagnostics (laboratory, BIA), treatment planning, prescription, and follow-up — can take place either in the regular consultation or in the extended consultation on Thursdays, depending on the depth needed. Scope and costs are discussed in advance.
Billing follows the GOÄ. Before the service is provided, we conclude a written agreement in accordance with § 18 (8) BMV-Ä with transparent cost information.
With accompanying type 2 diabetes, semaglutide may potentially be prescribed as a covered service for blood glucose control — the indication is assessed individually.
References
- Wilding JPH, Batterham RL, Calanna S et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). N Engl J Med. 2021;384(11):989–1002.
- Jastreboff AM, Aronne LJ, Ahmad NN et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). N Engl J Med. 2022;387(3):205–216.
- Lincoff AM, Brown-Frandsen K, Colhoun HM et al. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes (SELECT). N Engl J Med. 2023;389(24):2221–2232.
- Malhotra A, Grunstein RR, Gao L et al. Tirzepatide for the Treatment of Obstructive Sleep Apnea and Obesity (SURMOUNT-OSA). N Engl J Med. 2024;391(13):1193–1205.
- S3 Guidelines on Obesity — Prevention and Treatment. AWMF Registry No. 050-001, German Obesity Society (DAG), updated 2024.
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Email: info@internist-wenzel.de