Tirzepatide vs Semaglutide: SURMOUNT-5 72-Week Head-to-Head Trial
WELLNESS

Tirzepatide vs Semaglutide: SURMOUNT-5 72-Week Head-to-Head Trial

By Hyejin · · https://www.nejm.org/doi/full/10.1056/NEJMoa2416394
KO | EN

The direct comparison trial between two core obesity drugs, tirzepatide and semaglutide, was published in NEJM as SURMOUNT-5. In 751 non-diabetic obese adults compared over 72 weeks, tirzepatide showed superiority in both weight loss and waist circumference reduction.

SURMOUNT-5 trial design

Participants: 751 non-diabetic obese adults. BMI 30+ or 27+ with comorbidities.

Randomization: Tirzepatide 10 mg or 15 mg, semaglutide 2.4 mg. Once-weekly subcutaneous injection.

Duration: 72 weeks.

Primary endpoint: Percent change in body weight at week 72.

Core results

Body weight change percent (week 72, least-squares mean):

  • Tirzepatide: -20.2%
  • Semaglutide: -13.7%

Mean difference: Approximately 6.5%p greater loss with tirzepatide.

Waist circumference reduction: Tirzepatide superior.

Side effects: Both drugs showed GI side effects (nausea, vomiting, diarrhea) most frequently. Frequency and severity slightly higher with tirzepatide but clinically manageable.

Meta-analysis data

Combining multiple trials in meta-analysis.

Mean difference (MD): 4.23 kg (95% CI 3.22-5.25). Tirzepatide produces 4.23 kg greater loss on average.

Dose-dependent: Superiority is clearer at tirzepatide 10 mg+ doses.

Duration-dependent: Difference accumulates over time.

Real-world data

Data from real-world use beyond trials.

1-year average weight loss:

  • Semaglutide: -14.6 kg (14.1% of body weight)
  • Tirzepatide: -17.2 kg (16.5% of body weight)

Real-world effects are slightly smaller than trials, but the relative difference between drugs is consistent.

Mechanism difference

Semaglutide: Single GLP-1 receptor agonist. Appetite suppression, gastric emptying delay, insulin secretion stimulation.

Tirzepatide: GLP-1 + GIP (glucose-dependent insulinotropic polypeptide) dual receptor activation. GLP-1 effects + GIP’s insulin secretion stimulation and fat metabolism effects. The dual mechanism creates additional effect.

GIP is a hormone stimulating post-meal insulin secretion. Tirzepatide’s GIP receptor activation along with GLP-1 affects satiety, fat metabolism, and insulin sensitivity additionally for superior effect.

Which fits whom

Larger weight loss target: Tirzepatide. Population aiming for 20%+ loss.

More established use: Semaglutide. Longer-accumulated clinical data. Safety profile well-established.

Price-sensitive: Similar pricing tier. Insurance coverage matters.

Side effect-sensitive: Semaglutide generally has slightly milder side effect profile. Individual variability.

Cardiovascular protection target: Both have cardiovascular event reduction data. Semaglutide (LEADER, SUSTAIN-6) has older cardiovascular data.

Kidney protection target: This quarter’s semaglutide FLOW trial provides strong kidney event reduction data. Tirzepatide kidney trials are in progress.

Quality-of-weight-loss matrix

Beyond weight loss itself, quality of weight loss is becoming the standard. Both drugs require accompanying matrix.

Muscle preservation: Protein 1.2-1.6 g/kg/day, resistance training 2-3x weekly, HMB or leucine supplementation (65+).

Facial change: Collagen peptides, topical retinaldehyde, procedure options. This quarter’s GLP-1 aesthetic matrix (52% facial change concern).

Bone protection: D3 + K2 + calcium + resistance training. Combined with Mayo Clinic senolytic data.

Cognitive protection: Critical window hypothesis (MHT) or non-hormonal foundation (protein, B12, D, magnesium) for perimenopausal.

Kidney monitoring: Semaglutide FLOW data-based kidney protection standard. Tirzepatide awaits follow-up data.

Who should be careful

Type 1 diabetes: Not indicated.

Severe gastroparesis: Further slows gastric emptying. Worsening risk.

Pregnancy/breastfeeding: Insufficient data for both. Contraindicated.

Medullary thyroid cancer family history: Both have boxed warnings. Clinician evaluation.

Severe pancreatitis history: Pancreatitis risk assessment.

Eating disorder history: Appetite suppression and obsessive patterns may worsen. Mental health professional support.

Korean market significance

Both drugs are on the market in Korea. The Korean MFDS is gradually expanding obesity indications.

Insurance coverage: Limited for obesity-only indication. Some coverage for obesity + comorbidities (hypertension, dyslipidemia, type 2 diabetes).

Self-prescribing risk: Both are prescription drugs. Clinician evaluation and monitoring essential. Self-prescribing and direct overseas import carry safety risks.

Cosmetic-purpose use: Cosmetic-purpose use of obesity-only indication is in clinician judgment territory.

Daily guide

When starting or using GLP-1 or GIP/GLP-1, check the matrix.

Stage 1: Clinician evaluation. Indication, contraindications, monitoring plan.

Stage 2: Quality-of-weight-loss matrix. Protein, exercise, vitamin D, K2, omega-3.

Stage 3: Facial matrix. Collagen peptides, topical care. If procedures are needed, low-friction options for first-timers.

Stage 4: Monitoring. eGFR, blood pressure, lipids, HbA1c, muscle mass (body composition).

Stage 5: Discontinuation plan. Weight regain pattern after stopping. Matrix continuation is core.

GLP-1 and GIP/GLP-1 are powerful tools. The accompanying matrix determines weight loss quality. Drug alone delivers half the effect.