Wegovy vs Zepbound

Overview

Wegovy and Zepbound are brand names for two FDA-approved medications indicated specifically for chronic weight management. Wegovy contains semaglutide (2.4mg weekly), while Zepbound contains tirzepatide (up to 15mg weekly).

Both require use alongside reduced-calorie diet and increased physical activity for adults with obesity (BMI ≥30) or overweight (BMI ≥27) with weight-related comorbidities.

Key Facts

Aspect	Wegovy	Zepbound
Generic Name	Semaglutide	Tirzepatide
Manufacturer	Novo Nordisk	Eli Lilly
FDA Approval	2021 (obesity)	2023 (obesity)
Mechanism	GLP-1 agonist	Dual GLP-1/GIP agonist

Clinical Trial Evidence

STEP Program (Wegovy)

The STEP (Semaglutide Treatment Effect in People with Obesity) trials enrolled over 4,500 participants:

Trial	Population	Weight Loss
STEP 1	Adults without diabetes	-14.9% (vs -2.4% placebo)
STEP 2	Adults with T2D	-9.6% (vs -3.4% placebo)
STEP 3	With intensive behavioral	-16.0% (vs -5.7% placebo)
STEP 4	Withdrawal study	Maintained vs regain

SURMOUNT Program (Zepbound)

The SURMOUNT trials enrolled over 5,000 participants:

Trial	Population	Weight Loss
SURMOUNT-1	Adults without diabetes	-20.9% at 15mg (vs -3.1% placebo)
SURMOUNT-2	Adults with T2D	-14.7% at 15mg (vs -3.2% placebo)
SURMOUNT-3	With behavioral lead-in	-24.3% combined
SURMOUNT-4	Maintenance study	Maintained vs regain

Efficacy Comparison

Metric	Wegovy	Zepbound
Placebo-Adjusted Weight Loss	~12-15%	~15-18%
≥5% Weight Loss Achieved	86-88%	89-91%
≥10% Weight Loss Achieved	69-75%	78-83%
≥15% Weight Loss Achieved	50-56%	62-70%
≥20% Weight Loss Achieved	32-36%	48-57%

Ranges reflect different trial populations and doses

Mechanism Differences

Aspect	Wegovy	Zepbound
Receptor Targets	GLP-1 only	GLP-1 + GIP
Appetite Reduction	Central GLP-1 effects	Dual receptor central effects
Gastric Emptying	Slowed	Slowed
Metabolic Effects	Insulin sensitization	Enhanced insulin sensitization

Safety Comparison

Common Side Effects (≥5%)

Side Effect	Wegovy	Zepbound
Nausea	44%	24-31%
Diarrhea	30%	18-23%
Vomiting	24%	9-13%
Constipation	24%	17-23%
Abdominal pain	20%	10-14%
Headache	14%	8-10%
Fatigue	11%	5-7%

Note: Trial designs and reporting differ; direct comparison has limitations

Serious Warnings

Both medications share similar warnings:

• Thyroid C-cell tumors: Boxed warning based on rodent studies
• Pancreatitis: Discontinue if suspected
• Gallbladder disease: Increased risk of cholelithiasis
• Hypoglycemia: Risk with diabetes medications
• Acute kidney injury: Secondary to dehydration
• Suicidal ideation: Post-marketing reports (FDA monitoring)

Patient Considerations

Factor	Wegovy	Zepbound
Time on Market	Longer (2021)	Newer (2023)
Real-World Data	More extensive	Accumulating
Supply Issues	Intermittent shortages	Intermittent shortages
Cardiovascular Data	SELECT trial: CV benefit	CV trial ongoing

SELECT Trial Results (Wegovy)

The SELECT cardiovascular outcomes trial showed:

• 20% reduction in major adverse cardiovascular events (MACE)
• Benefit in overweight/obese adults with cardiovascular disease but without diabetes
• Led to expanded indication for cardiovascular risk reduction

Summary

Both Wegovy and Zepbound are FDA-approved for chronic weight management:

• Wegovy: First-in-class obesity GLP-1, extensive data, proven cardiovascular benefit
• Zepbound: Dual mechanism with potentially greater weight loss in trials, dosing flexibility

Key decision factors include:

• Individual efficacy and tolerability response
• Cardiovascular risk profile (SELECT trial data favors Wegovy currently)
• Insurance coverage and access
• Dose flexibility preferences

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This comparison is for educational purposes only. Medication decisions should be made with a healthcare provider.