Key Clinical Summary: Applying Obesity Guidelines to Adjust Therapy

This is a micro-learning module summary of Dr Sue Pedersen’s session which you can find here. Before participating, please read our CME and disclosure information which can be found here.

Acknowledgment: This activity is supported by an independent medical educational grant from Lilly. This online education program has been designed for healthcare professionals globally.

Introduction

Applying guideline-concordant obesity care requires ongoing reassessment, shared decision-making, and readiness to adjust therapy when agreed targets are not met. This summary outlines how to evaluate treatment response, identify barriers, and select alternative therapies that align with patient-defined goals.

Case Study: Sabine

Sabine, 62, is retired and lives with severe obstructive sleep apnea (OSA) without CPAP tolerance, knee osteoarthritis, controlled hypertension, hypothyroidism, mild chronic kidney disease (eGFR 55), and obesity. Her assessment shows: BMI 34, waist-to-height ratio 0.64, waist circumference 100 cm, normal A1C and BP, stable thyroid function, and mildly elevated triglycerides. She is currently taking semaglutide 2.4 mg weekly for weight management.

Her treatment goals were co-created with her clinicians, identifying three priorities: reduce knee pain, improve ISA and achieve ≥15% weight loss. After nine months of semaglutide, she reports mild improvement in knee pain, modest improvement in OSA, and a 5% weight reduction with a plateau.

When Targets Are Not Met: Reassessment First

A suboptimal response does not automatically mean treatment failure. Before modifying therapy, clinicians should explore:

• Access and affordability: Is the patient still able to obtain treatment consistently?
• Adequacy of dose: Has the patient reached the maximum tolerated dose?
• Adherence and tolerance: Any missed doses, side effects, or interruptions?
• Behavioural barriers: Sleep, stress, nutrition patterns, or activity limitations.
• Psychosocial or medical contributors: New medications, mental health burdens, or weight-promoting conditions.

Once these factors are clarified, and if targets remain unmet at the maximum tolerated dose, the three pillars of obesity management (psychological support, pharmacotherapy and bariatric surgery) can be revisited. Addition or substitution of medication can also be considered.

Evidence-Based Options for Sabine

When Sabine’s response to semaglutide plateaued, the question wasn’t simply “what else lowers weight?” but “what therapy/management strategy best matches the specific goals she set and the conditions shaping her health?” This is where comparative evidence becomes crucial.

• Tirzepatide vs Semaglutide: SURMOUNT-5 provides one of the clearest head-to-head comparisons in obesity pharmacotherapy. In this trial, tirzepatide produced:
• 20.2% mean weight reduction vs 13.7% with semaglutide
• ≥15% weight loss in ~65% vs ~40% with semaglutide

Given Sabine’s goal of ≥15% weight loss, tirzepatide offers a higher probability of achieving her target.

• Obstructive Sleep Apnea: OSA is one of Sabine’s most burdensome conditions. There is robust evidence from the SURMOUNT-OSA trial for tirzepatide improving OSA. In patients not using CPAP, mirroring Sabine’s situation, tirzepatide produced marked reductions in the Apnea–Hypopnea Index (AHI), dropping roughly 25 events/hour with an average of nearly 18% weight loss. In contrast, liraglutide shows modest benefit for OSA as well, but its impact is smaller and heavily weight dependent. For Sabine, who needs a more robust shift in disease burden, tirzepatide offers a more clinically meaningful path.
• Osteoarthritis: Semaglutide is the only anti-obesity medication with dedicated evidence for improving knee osteoarthritis pain measured with the WOMAC pain score. However, Sabine has already been on semaglutide at maximum dose with only mild relief, suggesting that further benefits from this mechanism alone are unlikely.

Decision Tool Integration

Using the Obesity Canada Decision Table, tirzepatide emerges as the most suitable alternative for Sabine across:

• Weight loss magnitude
• OSA improvement
• Limited response to semaglutide

Treatment Adjustment Plan

• Switching from Semaglutide to Tirzepatide. Because Sabine tolerated semaglutide well, a reasonable switch would be to start tirzepatide at 5 mg weekly (titrate as needed). A 7.5 mg start may be acceptable based on clinical judgement, but most clinicians opt for the more conservative approach.
• Monitoring After Switch: Highly effective GLP-based therapies can influence comorbidities even before major weight changes.
• Blood pressure: Hypertension medication requirements may decrease early. Home monitoring and prompt adjustment are essential.
• Thyroid hormone: Weight loss can reduce levothyroxine needs. TSH should be checked every 1–2 months during the first six months, and one month after any dose change. Frequency can later be reduced if weight change stabilises.

Monitoring plans must be individualised, especially in patients with comorbidities such as CAD.

Conclusion

Sabine’s partial response highlights a common clinical scenario: meaningful improvement, but not enough to meet patient-defined goals. After reassessing barriers and confirming maximal dosing, switching from semaglutide to tirzepatide aligns with her treatment priorities and current evidence. Guideline-based obesity care remains a dynamic, collaborative process, rooted in shared targets, structured monitoring, and timely therapeutic adjustments that support sustained improvements in weight and health.