The Ultimate Shred Stack
Retatrutide + Tesamorelin

Why the Scale Lies to You About Your Actual Health

You can lose 30 pounds and still look like hell in the mirror. You can hit your goal weight and still have elevated liver enzymes, high CRP, and insulin resistance that's quietly seeding metabolic disease. The scale doesn't distinguish between the fat that matters and the fat that doesn't — and that distinction is everything.

There are two fundamentally different types of body fat, and your body treats them very differently. Subcutaneous fat is the fat you can pinch — it sits between your skin and muscle. It's cosmetically annoying but metabolically mostly harmless. It stores energy, provides insulation, and beyond a certain point it's just extra padding.

Visceral fat is the one that will kill you. It wraps around your organs — liver, pancreas, intestines — and it's not just sitting there passively. Visceral adipose tissue is metabolically active. It pumps out inflammatory cytokines (TNF-alpha, IL-6), drives insulin resistance directly through portal vein delivery of free fatty acids to the liver, and seeds non-alcoholic fatty liver disease. This is why the concept of TOFI — Thin Outside, Fat Inside — exists. You can be normal weight with a BMI of 22 and still have dangerous levels of visceral fat silently driving metabolic dysfunction.

Standard weight loss approaches reduce both types of fat proportionally. That's the default. Caloric restriction, cardio, even GLP-1 drugs — they don't preferentially target visceral over subcutaneous. You can drop 30 pounds on semaglutide and find your liver enzymes and CRP are still elevated because the visceral compartment didn't come off fast enough relative to total weight lost.

And there's a bigger problem with GLP-1 monotherapy: it eats muscle. The STEP-1 trial DXA data showed that approximately 40% of weight lost on semaglutide was lean tissue. Not fat — muscle, bone mineral density, everything that isn't adipose. Tirzepatide performs somewhat better at roughly 25% lean tissue loss, but that's still a quarter of your hard-earned muscle disappearing alongside the fat.

This stack attacks both problems simultaneously. Retatrutide drives total fat loss through triple receptor agonism — GLP-1, GIP, and glucagon — creating a deeper caloric deficit and enhanced lipid oxidation beyond what any dual agonist can achieve. Tesamorelin targets visceral fat specifically at a roughly 25:1 selectivity ratio over subcutaneous fat while simultaneously preserving lean body mass through GH-mediated anabolic signaling.

Retatrutide — The Triple Agonist Nobody Saw Coming

Retatrutide (LY3437943, Eli Lilly) is the first triple GLP-1/GIP/glucagon receptor agonist to reach advanced clinical development. While semaglutide hits one receptor and tirzepatide hits two, retatrutide activates all three — and that third receptor is the one that changes the entire equation.

Why the Glucagon Receptor Matters

Insulin is the storage hormone. Glucagon is the release hormone. They're the yin and yang of metabolic regulation. Semaglutide and tirzepatide primarily make you eat less through GLP-1 mediated appetite suppression and GIP-mediated satiety signaling. That's powerful, but it's only half the equation.

Retatrutide makes you eat less and burn more. The glucagon receptor component drives hepatic lipid oxidation — your liver starts mobilizing and burning its own fat stores. It increases energy expenditure. It enhances metabolic flexibility, meaning your body becomes better at switching between glucose and fat as fuel sources. This is why retatrutide's weight loss numbers are consistently ahead of anything else in the pipeline.

The Clinical Data

Phase 2 (Jastreboff et al., New England Journal of Medicine, 2023; PMID: 37366315): 338 adults with obesity, 48 weeks of treatment. The 12mg dose produced a 24.2% mean weight reduction. Response rates were extraordinary — 100% of participants achieved at least 5% weight loss, 93% hit 10% or more, 83% reached 15% or more. And critically, the weight loss curves had not plateaued at 48 weeks. They were still descending.

Phase 3 TRIUMPH-4 (December 2025): 28.7% mean weight loss at 68 weeks, translating to an average of 71.2 pounds lost. TRANSCEND-T2D-1 (March 2026): In type 2 diabetes patients, HbA1c dropped 2.0 percentage points with 36.6 pounds lost over 40 weeks.

The Liver Fat Story

A prespecified substudy analyzed retatrutide's impact on hepatic steatosis (Sanyal et al., Nature Medicine, 2024; PMID: 38858523). The results were remarkable: 86% reduction in liver fat at the 12mg dose over 48 weeks. 93% of participants reached normal hepatic fat levels (below 5%). HOMA2-IR dropped 69.3%, fasting insulin fell 70.9%, adiponectin increased 99.3%, and beta-hydroxybutyrate rose 181% — indicating a massive shift toward fat oxidation as a primary fuel source.

Pharmacokinetics

Retatrutide has a half-life of approximately 6 days (Urva et al., The Lancet, 2022; PMID: 36354040), supporting once-weekly dosing. Single-dose pharmacodynamic effects persist for up to 43 days, meaning the compound has a long tail of activity even after discontinuation. Steady state is reached within 4-5 weeks of consistent weekly dosing.

Tesamorelin — The Visceral Fat Assassin

Tesamorelin is a synthetic analog of growth hormone-releasing hormone (GHRH). Rather than injecting exogenous growth hormone directly, tesamorelin stimulates your pituitary gland to release growth hormone in natural pulsatile patterns — the way your body is designed to produce it.

It was FDA approved in November 2010 under the brand name Egrifta for the treatment of HIV-associated lipodystrophy — a condition where antiretroviral drugs cause abnormal visceral fat accumulation. It is the only FDA-approved drug specifically indicated as a visceral fat reducer.

Phase 3 Data — The 25:1 Ratio

Pooled Phase 3 data (Falutz et al., Journal of Clinical Endocrinology & Metabolism, 2010; PMID: 20554713) included 806 patients over 26 weeks. Visceral adipose tissue (VAT) decreased by 15.4%. Subcutaneous adipose tissue (SAT) decreased by just 0.6% — which was not statistically significant. That gives you a roughly 25:1 selectivity ratio for visceral over subcutaneous fat. Lean body mass increased by 1.2-1.3 kg. Tesamorelin doesn't just burn visceral fat — it preserves and slightly builds muscle tissue simultaneously.

Why Visceral-Specific?

The mechanism behind this selectivity is receptor density. Visceral adipose tissue has significantly higher GH and IGF-1 receptor density compared to subcutaneous fat depots. When tesamorelin triggers a GH pulse, visceral tissue is disproportionately exposed to the lipolytic signal. The fat that's hardest to reach with diet and exercise is the fat most responsive to this specific pathway.

Beyond HIV — Data in General Obesity

A critical study for this stack's rationale is Makimura et al. (JCEM, 2012; PMID: 23015655): 60 obese adults without HIV, 12 months of treatment. VAT decreased by 35 cm² with no significant change in subcutaneous fat. But the downstream metabolic effects were equally important — improved carotid intima-media thickness (a cardiovascular risk marker), reduced CRP (systemic inflammation), and improved triglycerides.

Liver Fat Reduction

Stanley et al. (Lancet HIV, 2019; PMID: 31611038) ran a 12-month randomized controlled trial examining tesamorelin's effect on hepatic fat. Results: 37% reduction in hepatic fat, with 35% of tesamorelin patients achieving NAFLD resolution compared to just 4% on placebo. Fibrosis progression occurred in only 10.5% of tesamorelin patients versus 37.5% on placebo.

IGF-1 Response and Monitoring

Tesamorelin increases IGF-1 levels by approximately 81-108 ng/mL at the 2mg daily dose and roughly 117% above baseline at 1mg daily (Baker et al.; PMID: 22869065). Target range is 50-100% above your individual baseline. If IGF-1 exceeds 350 ng/mL, reduce the dose. If it exceeds 400 ng/mL, stop tesamorelin and recheck in 4 weeks.

Timing and Administration

Tesamorelin has a plasma half-life of just 26-38 minutes. Each injection triggers a single endogenous GH pulse that peaks within 15-30 minutes and returns to baseline within 2-3 hours. This makes timing critical: inject in the evening, fully fasted, 30-60 minutes before bed, and at least 2 hours after your last meal. Growth hormone release is suppressed by insulin and glucose, so a fasted state maximizes the GH pulse amplitude.

Why the Stack Works — Two Pathways, Zero Overlap

These two compounds operate on completely separate receptor systems. There is no competition, no antagonism, no shared metabolic pathway. They attack body composition from two entirely different angles that complement rather than interfere with each other.

The Retatrutide Axis

GLP-1 + GIP + glucagon receptor activation drives appetite suppression, hepatic lipid oxidation, enhanced metabolic flexibility, increased energy expenditure, and improved insulin sensitivity. This creates the caloric deficit and the metabolic environment for fat mobilization. Retatrutide is the catabolic driver — it makes your body release and burn stored fat.

The Tesamorelin Axis

GHRH receptor activation triggers pulsatile endogenous GH release, which drives IGF-1 production. This pathway provides visceral-selective lipolysis, lean mass preservation, and cognitive enhancement through GH/IGF-1 signaling. Tesamorelin is the anabolic signal — it tells your body to burn visceral fat specifically while protecting (and slightly building) muscle tissue.

The Recomp Math

Retatrutide creates the caloric deficit and drives total fat loss. Tesamorelin provides the anabolic signal that preserves lean tissue during that deficit. In a typical aggressive cut without pharmacological support, you might lose 3 pounds of muscle for every 7 pounds of fat. With this stack, the theoretical ratio shifts dramatically — more fat loss, less (potentially no) lean tissue loss, and preferential reduction of the most metabolically dangerous fat depot.

The Glucose Question

One legitimate concern with stacking: tesamorelin can cause a transient fasting glucose increase of 7-9 mg/dL in the first weeks of treatment (Stanley et al., 2014; PMID: 25038357). This typically resolves by 6-12 months. More importantly, in strong responders — those achieving 8% or greater VAT reduction — fasting glucose actually decreases (PMID: 22495074). When you factor in retatrutide's 69.3% reduction in HOMA2-IR, the net effect on glucose metabolism strongly favors improvement.

The Protocol — Dosing, Timing, Cycle Length

Retatrutide Dosing

Retatrutide is dosed weekly at 1-4mg with a slow titration to minimize GI side effects. Subcutaneous injection, rotate injection sites, Sunday evening preferred for scheduling consistency.

Reconstitution: Add 1 mL bacteriostatic water per 10 mg vial to yield a concentration of 10 mg/mL. For a 2 mg dose, draw 0.20 mL (20 units on an insulin syringe). Store reconstituted vial refrigerated, use within 30 days.

Tesamorelin Dosing

Tesamorelin is dosed at 1 mg daily, 5 days on / 2 days off (5 mg total per week). Evening administration, fully fasted, 30-60 minutes before bed, minimum 2 hours after last meal. Subcutaneous injection in the abdomen.

Reconstitution: Add 3 mL bacteriostatic water per 10 mg vial to yield a concentration of 3.33 mg/mL. For a 1 mg dose, draw 0.30 mL (30 units on an insulin syringe). Reconstituted tesamorelin is less stable than retatrutide — use within 7 days and keep refrigerated at all times.

Cycle Length

• 8 weeks minimum — enough time for retatrutide to reach full titration and tesamorelin to establish consistent GH pulsing
• 12 weeks standard — full titration plus 4-8 weeks at target dose, sufficient for meaningful visceral fat reduction and metabolic marker improvement
• 16 weeks advanced — for those with significant visceral fat burden. Take a tesamorelin break (2 weeks off) every 6-8 weeks to allow IGF-1 to normalize and prevent receptor desensitization

Recomp Calculator

Use this calculator to estimate your projected body composition changes based on starting stats, protocol duration, and adherence level. These projections are based on published clinical trial data extrapolated to stack protocols.

Visceral Fat Reduction Timeline

Projected change over a 16-week protocol

Dosing Schedule Visualizer

Interactive weekly schedule showing exactly when to inject each compound, when to do bloodwork, and how the titration progresses over the full cycle.

Cost Breakdown

One of the most common questions is whether this stack is affordable outside of a clinical trial setting. Research-grade peptides are significantly cheaper than pharmaceutical equivalents, but the total cost includes more than just the compounds — you need bacteriostatic water, syringes, alcohol swabs, sharps disposal, and bloodwork at minimum. Use the calculator below to estimate your total protocol cost.

Bloodwork You Need to Run

Running this stack without bloodwork is irresponsible. Tesamorelin directly raises IGF-1 levels, and retatrutide dramatically shifts metabolic markers. You need objective data to confirm the stack is doing what it should and to catch any issues early.

Baseline Panel (Before Starting)

• CBC — complete blood count
• CMP — comprehensive metabolic panel (kidney, electrolytes)
• Lipid panel — total cholesterol, LDL, HDL, triglycerides
• Fasting glucose + fasting insulin — calculate HOMA-IR
• HbA1c — 3-month average blood sugar
• Thyroid panel — TSH, free T3, free T4
• IGF-1 — mandatory baseline for tesamorelin monitoring
• Testosterone — total and free (GH axis can affect sex hormones)
• Liver enzymes — ALT, AST, GGT (especially important given liver fat targeting)
• CRP — high-sensitivity C-reactive protein (inflammatory marker)

Week 4 — Mini Panel

• IGF-1 — confirm tesamorelin is working and levels are in target range
• Fasting glucose — check for tesamorelin-related glucose elevation
• Fasting insulin — paired with glucose for HOMA-IR reassessment

Week 8 — Full Repeat

Run the entire baseline panel again. By week 8 you should be at or near full retatrutide dose and tesamorelin will have been running for 8 weeks. This is your first comprehensive check — compare every marker to baseline. Expect to see liver enzymes trending down, lipids improving, HOMA-IR decreasing, and IGF-1 elevated but within target.

Week 12 — End of Protocol

Final comprehensive panel. This is your outcome data — the before-and-after comparison that tells you exactly what the stack accomplished. If continuing beyond 12 weeks, this becomes your new baseline for the extension period.

IGF-1 Targets

Safety, Side Effects, and Red Flags

Retatrutide Side Effects

GI effects are the primary tolerability concern and the reason for slow titration. From published Phase 2 data:

• Nausea — 14-60% (dose dependent, worst during titration)
• Diarrhea — 9-20%
• Vomiting — 3-26%
• Constipation — 7-16%
• Heart rate increase — +5-10 bpm above baseline (class effect of GLP-1 agonists)
• Dysesthesia — 8.8-20.9% (unusual tingling/altered sensation, unique to retatrutide among GLP-1 class)

Tesamorelin Side Effects

• Injection site reactions — redness, swelling, itching at injection site
• Fluid retention — mild edema in the first 1-3 weeks, typically self-resolving
• Joint stiffness — especially hands and wrists, related to GH-mediated fluid shifts
• Hand paresthesia — tingling in fingers, can indicate carpal tunnel compression from fluid retention
• Transient glucose elevation — +7-9 mg/dL fasting glucose in first weeks

Absolute Contraindications

Relative Contraindications — Proceed with Caution

• Type 2 diabetes — monitor glucose closely, coordinate with physician
• Diabetic retinopathy — GH/IGF-1 elevation may worsen existing retinopathy
• Uncontrolled hypertension — GLP-1 agonist HR increase + GH fluid retention
• History of arrhythmias — heart rate increase from retatrutide requires monitoring
• History of pancreatitis — GLP-1 class has rare but documented pancreatitis risk

When to Stop Immediately

Who This Stack Is Actually For

This Stack Is FOR You If:

• You have stubborn visceral fat that hasn't responded to diet, training, and caloric restriction
• You have fatty liver or elevated liver enzymes and want to address the root cause pharmacologically
• You have insulin resistance or prediabetes and want aggressive metabolic improvement
• You've lost muscle on GLP-1 monotherapy and want a recomposition approach instead of pure weight loss
• You're a health optimizer who understands this is a research protocol, not a prescription
• You train consistently (3-5x/week resistance training) and hit your protein targets (0.8-1g per pound of lean body mass)
• You run bloodwork before, during, and after the protocol — no exceptions
• You understand this is a research protocol with an evidence-based rationale but without a dedicated combination clinical trial

This Stack Is NOT For You If:

• You just want to drop 20 pounds quick — semaglutide or tirzepatide alone will do that
• You won't do bloodwork — running tesamorelin without IGF-1 monitoring is reckless
• You don't train or eat adequate protein — the anabolic signal from tesamorelin requires mechanical loading and amino acid availability to translate into lean mass preservation
• You're looking for a magic bullet — this stack amplifies the work you're already doing, it doesn't replace it
• You have any absolute contraindication listed above
• You can't afford the full stack — compounds, bloodwork, training, and protein intake are all mandatory components, not optional add-ons

FAQ

Citations

1. Jastreboff AM, et al. Triple-hormone-receptor agonist retatrutide for obesity — A Phase 2 trial. N Engl J Med. 2023. PMID: 37366315
2. Sanyal AJ, et al. Retatrutide and hepatic steatosis substudy. Nat Med. 2024. PMID: 38858523
3. Urva S, et al. Single and multiple ascending dose study of retatrutide (LY3437943). Lancet. 2022. PMID: 36354040
4. Falutz J, et al. Pooled Phase 3 tesamorelin data in HIV-associated lipodystrophy. J Clin Endocrinol Metab. 2010. PMID: 20554713
5. Makimura H, et al. Tesamorelin reduces visceral fat in obese adults without HIV. J Clin Endocrinol Metab. 2012. PMID: 23015655
6. Stanley TL, et al. Tesamorelin reduces hepatic fat and fibrosis in NAFLD. Lancet HIV. 2019. PMID: 31611038
7. Baker JV, et al. Tesamorelin IGF-1 response and dose-dependent effects. PMID: 22869065
8. Stanley TL, et al. Transient glucose effects of tesamorelin. 2014. PMID: 25038357
9. Falutz J, et al. Glucose and tesamorelin responders — VAT reduction and metabolic improvement. PMID: 22495074
10. TRIUMPH-4 Phase 3 results. Eli Lilly press release, December 2025.
11. TRANSCEND-T2D-1 Phase 3 results. Eli Lilly press release, March 2026.
12. STEP-1 DXA body composition data. Semaglutide lean tissue loss analysis.
13. Tirzepatide DXA body composition substudy data. SURMOUNT program.
14. Egrifta (tesamorelin) FDA prescribing information. Theratechnologies Inc. Approved November 2010.
15. Retatrutide LY3437943 clinical development timeline. ClinicalTrials.gov NCT05929066, NCT06163651.