Feeling run down despite getting enough rest and staying hydrated can be discouraging
The starting dose of retatrutide is where your entire protocol succeeds or fails, and getting it wrong creates problems that follow you for months
Evercore ISI Panel Members of Skyes management team
In parallel, Eli Lilly developed tirzepatide (Mounjaro)--a dual GLP-1 and GIP receptor agonist
TRIUMPH-4 (Retatrutide) - 28.7% Weight Loss Study design: 445 adults with obesity and knee osteoarthritis 68 weeks duration Published December 2025 Results at 12mg: Average weight loss: 28.7% (32.3 kg / 71.2 lbs) 20% responders: 73.4% 25% responders: 58.6% SURMOUNT-1 (Tirzepatide) - 22.5% Weight Loss Study design: 2,539 adults with obesity 72 weeks duration Published June 2022 Results at 15mg: Average weight loss: 22.5% (24 kg / 52 lbs) 20% responders: 57% 25% responders: 43% STEP 1 (Semaglutide) - 14.9% Weight Loss Study design: 1,961 adults with obesity 68 weeks duration Published March 2021 Results at 2.4mg: Average weight loss: 14.9% (15.3 kg / 33.7 lbs) 20% responders: 32% 25% responders: 12% Head-to-Head Comparison Key findings: Retatrutide vs Semaglutide: 93% more weight loss (28.7% vs 14.9%) Tirzepatide vs Semaglutide: 51% more weight loss (22.5% vs 14.9%) Retatrutide vs Tirzepatide: 28% more weight loss (28.7% vs 22.5%) Practical example for 100kg (220 lb) person: Semaglutide: 14.9 kg loss (33 lbs) 85.1 kg (188 lbs) Tirzepatide: 22.5 kg loss (50 lbs) 77.5 kg (171 lbs) Retatrutide: 28.7 kg loss (63 lbs) 71.3 kg (157 lbs) Mechanism of Action: Single vs Dual vs Triple Semaglutide: Single Agonist (GLP-1 Only) Targets one receptor: GLP-1: Reduces appetite, slows digestion, enhances insulin Brands: Ozempic (diabetes, 1mg weekly) Wegovy (weight loss, 2.4mg weekly) Effectiveness: 14.9% average weight loss Tirzepatide: Dual Agonist (GLP-1 + GIP) Targets two receptors: GLP-1: Appetite suppression GIP: Insulin sensitivity, metabolic improvement Brands: Mounjaro (diabetes, up to 15mg) Zepbound (weight loss, up to 15mg) Effectiveness: 22.5% average weight loss51% better than Semaglutide Retatrutide: Triple Agonist (GLP-1 + GIP + Glucagon) Targets three receptors: GLP-1: Appetite control GIP: Metabolic efficiency Glucagon: Energy expenditure, fat burning Status: Investigational (not yet FDA-approved) Effectiveness: 28.7% average weight loss93% better than Semaglutide Mechanism Comparison Table Why more targets = more weight loss: 1 target (Sema): Reduces calories in 15% weight loss 2 targets (Tirz): Reduces calories in + improves metabolism 22.5% weight loss 3 targets (Reta): Reduces calories in + improves metabolism + increases calories out 28.7% weight loss Safety and Side Effects Comparison Common Side Effects Key findings: Tirzepatide has the best tolerability profile: Lowest nausea (31% vs 43-44%) Lowest discontinuation among newer drugs (6.2%) Better GI side effects than either Retatrutide or Semaglutide Semaglutide has lowest discontinuation overall: Only 6.9% discontinued (best retention) Five years of real-world safety data Retatrutide has highest discontinuation: 18.2% discontinued (likely due to glucagon component) Limited safety data (investigational) Dosing Schedules Semaglutide (Wegovy): Week 1-4: 0.25mg Week 5-8: 0.5mg Week 9-12: 1mg Week 13-16: 1.7mg Week 17+: 2.4mg Tirzepatide (Zepbound): Week 1-4: 2.5mg Week 5-8: 5mg Week 9-12: 10mg Week 13+: 15mg Retatrutide (expected): Week 1-4: 2mg Week 5-8: 4mg Week 9-12: 6mg Week 13-16: 9mg Week 17+: 12mg (confirmed from TRIUMPH-4 Phase 3 protocol, Lilly press release December 2025) FDA Approval Status and Availability Semaglutide: First to Market (2021) FDA approval: 2017: Ozempic approved for diabetes June 2021: Wegovy approved for weight loss 5 years market experience Current availability: Available by prescription nationwide Cost: ~$1,349/month without insurance Tirzepatide: Newest Approved Option (2023) FDA approval: May 2022: Mounjaro approved for diabetes November 2023: Zepbound approved for weight loss 3 years market experience Current availability: Available by prescription nationwide Cost: ~$1,060/month without insurance Retatrutide: Investigational (2027-2028) Current status: Not FDA-approved (all four core Phase 3 trials now complete) Not available for prescription Access limited to clinical trial participants Expected timeline: Q1 2027: BLA filing expected (Biologics License Application, not NDA retatrutide is a biologic) ~2 months after filing: FDA accepts BLA, review clock starts Q3 2027 to Q1Q2 2028: Possible approval (priority review vs
GLP-1 Receptor expression within the human heart
