Semaglutide vs Tirzepatide vs Retatrutide — Complete 2026 Comparison

The Quick Answer: Which One Loses the Most Weight?

Retatrutide. In Phase 3 trials, participants on 12mg retatrutide lost an average of 28.7% of their body weight (71.2 lbs / 32.3 kg) over 68 weeks. Tirzepatide at 15mg produced 22.5% weight loss over 72 weeks. Semaglutide at 2.4mg produced approximately 15% weight loss over 68 weeks.

But weight loss isn't the only factor. Semaglutide has the most real-world safety data and is the most accessible. Tirzepatide has the best balance of efficacy and availability. Retatrutide has the highest efficacy but isn't FDA-approved. Each has a different risk-benefit profile depending on your situation.

Master Comparison Table

How Each One Works (Mechanism of Action)

Think of it as a volume dial:

• Semaglutide turns down your hunger (1 lever)
• Tirzepatide turns down hunger AND improves fat processing (2 levers)
• Retatrutide turns down hunger, improves fat processing, AND turns up your body's calorie burn (3 levers)

Each additional receptor doesn't just add to the effect — it compounds it. The glucagon receptor in retatrutide is particularly significant because it's the first weight loss compound that actively increases energy expenditure rather than just reducing energy intake.

Weight Loss Results: The Data

Semaglutide (STEP 1 Trial)

• Dose: 2.4mg/week
• Duration: 68 weeks
• Average weight loss: 14.9% body weight
• Patients reaching 10%+ loss: ~70%
• Patients reaching 20%+ loss: ~32%

Tirzepatide (SURMOUNT-1 Trial)

• Dose: 15mg/week
• Duration: 72 weeks
• Average weight loss: 22.5% body weight
• Patients reaching 10%+ loss: ~91%
• Patients reaching 20%+ loss: ~55%

Retatrutide (TRIUMPH-4 Trial)

• Dose: 12mg/week
• Duration: 68 weeks
• Average weight loss: 28.7% body weight (71.2 lbs / 32.3 kg)
• Patients reaching 15%+ loss: ~80%
• Patients reaching 20%+ loss: ~70%

Additional retatrutide findings from TRIUMPH-4:

• Also produced significant improvements in knee osteoarthritis pain
• Reduced cardiovascular risk markers (non-HDL cholesterol, systolic blood pressure)
• 9mg group achieved 26.4% weight loss — nearly as effective as 12mg with fewer side effects

Side Effects Compared

Key differences:

• Semaglutide has the mildest side effect profile overall but also the least weight loss
• Tirzepatide has a similar side effect profile to semaglutide with modestly higher efficacy
• Retatrutide has the most intense side effects — particularly the glucagon-driven nausea at higher doses and the heart rate elevation — but also the most weight loss

For detailed side effect management at each retatrutide dose tier, see our Retatrutide Side Effects Guide.

Cost and Availability

The practical reality for most people:

• If you have insurance that covers GLP-1s, tirzepatide (Zepbound) is the best value — better results than semaglutide at similar out-of-pocket cost
• If you're paying out of pocket through compounding, tirzepatide offers the best bang for your buck
• Retatrutide is the most expensive option AND carries the risk of using an unapproved compound — it makes sense primarily for people who've genuinely plateaued on tirzepatide

The Upgrade Path: Sema to Tirz to Reta

A growing number of people follow a progression through all three compounds. Here's how it typically works:

Stage 1: Semaglutide (months 1-6+)

• Start here if you're new to GLP-1 medications
• Most accessible, most safety data, insurance-friendly
• Expect 10-15% body weight loss
• Move to Stage 2 if: weight loss stalls after 3+ months at max dose, or you want faster results

Stage 2: Tirzepatide (months 6-12+)

• Upgrade when semaglutide plateau hits
• Dual mechanism often restarts weight loss
• Expect additional 7-10% body weight loss
• Move to Stage 3 if: plateau on max tirz dose after 2+ months AND you've optimized diet/exercise

Stage 3: Retatrutide (when available or via compounding)

• The "final level" for maximum weight loss
• Triple mechanism breaks through dual-agonist plateaus
• Expect additional 5-10% body weight loss beyond tirzepatide
• Not everyone needs this stage — many people reach their goal weight on tirzepatide

Which One Is Right for You?

Start with semaglutide if:

• You're new to GLP-1 medications and want the safest entry point
• Your insurance covers Ozempic or Wegovy
• You have 30-50 lbs to lose
• You prefer the compound with the most published long-term safety data

Choose tirzepatide if:

• You've plateaued on semaglutide or want stronger initial results
• Your insurance covers Mounjaro or Zepbound
• You have 50-80+ lbs to lose
• You want the best balance of efficacy, safety, and accessibility

Consider retatrutide if:

• You've genuinely plateaued on tirzepatide at max dose
• You have a BMI of 40+ and need maximum weight loss
• You're comfortable with an investigational compound
• You train regularly and prioritize muscle preservation during fat loss
• You're working with a provider who can monitor your labs and progress

Tracking Any GLP-1 Protocol

Track semaglutide, tirzepatide, or retatrutide — all in one app

• Dose logging and smart reminders for any compound
• Pharmacokinetic blood level modeling (see your peaks and troughs)
• Weight trend tracking with 7-day moving averages

Get Regimen Free

Whether you're on your first week of semaglutide or switching from tirzepatide to retatrutide, tracking makes every protocol more effective. The Regimen app supports all three compounds with dose logging, PK curve modeling, weight trends, side effect logging, and progress photos.

Semaglutide Tracker · Tirzepatide Tracker · Retatrutide Tracker · GLP-1 Dose Calculator

Frequently Asked Questions

Related Articles

• Retatrutide vs Tirzepatide — Detailed Comparison
• Retatrutide Dosing Guide — 2mg to 12mg Protocol
• Retatrutide Side Effects Guide
• Retatrutide Reconstitution Calculator Guide
• GLP-1 Plateau Guide: Why You Stopped Losing Weight
• Tirzepatide Reconstitution Calculator Guide
• Semaglutide Reconstitution Calculator Guide