| At a Glance | |
|---|---|
| Who it's for | Retatrutide users who want appetite control without the energy crash |
| Duration | 12 weeks |
| Key components | Retatrutide (0.25–4 mg/week) + NAD+ (100–250 mg IM, 2–3×/week) |
| Results timeline | Appetite changes often appear early; body-composition changes follow |
| Difficulty | Beginner |
Retatrutide lowers intake and changes fuel handling through GIP, GLP-1, and glucagon signaling. NAD+ does not replace that work. It supports the downstream step that matters once stored fat is mobilized: beta-oxidation, where fatty acids are converted into ATP.
That pathway is NAD+-dependent. If NAD+ availability or recycling is low, the user may still be in a deficit but feel flat, cold, foggy, restless, or underpowered. This protocol pairs retatrutide with NAD+ from the start so appetite control and oxidation capacity move together.
Who This Is For
This is for retatrutide users who want:
- Clear structure with minimal complexity
- Appetite control without energy collapse
- A foundation for more advanced protocols later
- A conservative starting point before adding MOTS-c, L-Carnitine, or GH-axis support
The goal is not aggressive weight loss at the expense of training output, sleep, or lean-mass protection. It is a clean metabolic base: lower appetite, better glucose control, and enough redox capacity to actually use the fuel being released.
Why These Two Together
Retatrutide¹ (LY3437943, developed by Eli Lilly) is a triple agonist engineered with deliberately uneven arms — not three equal ones. Strength against each receptor's native hormone:
| Receptor | What it does | Strength vs. native |
|---|---|---|
| GLP-1R | Appetite suppression, gastric slowing | Softer |
| GIPR | Insulin efficiency, adipose thermogenesis | Much harder |
| GCGR | Hepatic fat oxidation, energy expenditure | Softer |
The row that reshapes the dose decision is GIPR. Retatrutide's GIP signal is much stronger than your body's native GIP — and stronger than tirzepatide's at any clinical dose. What this means in practice: even at 1 mg weekly, retatrutide is a GIP-dominant drug, with softer GLP-1 (about 40% of what semaglutide produces) and a glucagon arm whose effects scale with dose.
Glucagon-mediated effects are threshold-dependent. At lower doses the signal is more liver-facing: hepatic fat handling, glucose output, and energy-expenditure pressure. As exposure rises, peripheral effects become more obvious: resting heart-rate elevation, chills, skin sensitivity, insomnia, and a more catabolic feel. Lean or metabolically healthier users can feel these signals earlier than the obesity trial averages imply.
The dose decision is therefore not just "how much weight loss." It is how quickly the user pushes GIP, GLP-1, and glucagon engagement at once. Many beginner, lean, sensitive, South Asian, or tirzepatide-transition users belong closer to 0.25–1 mg at the start, with 4+ week holds before escalation.
But mobilized fat still needs to be burned. That's where NAD+ becomes essential.
In a deficit, cells lean heavily on β-oxidation—the pathway that converts fat to ATP. This pathway spends NAD+ every cycle.² When demand outruns availability or recycling, fat can be mobilized faster than it is comfortably converted to usable energy.³ Fatigue sets in. Cravings return. Progress stalls.
Retatrutide makes this more acute than other GLP-1 drugs. Its glucagon receptor activation increases fat oxidation specifically in the liver—which is also the primary site for NAD+ production and recycling. You're increasing demand for NAD+ at the organ responsible for maintaining NAD+ supply. The math is tighter with retatrutide than with semaglutide or tirzepatide, where the metabolic load is distributed differently.
Maintaining NAD+ keeps the fat-burn → ATP chain from becoming the weak link. The target is not stronger appetite suppression. The target is better tolerance of the deficit retatrutide already created.
Preventing the Metabolic Wall
Users of GLP-1 drugs often hit a "wall" around months 3-6. Weight loss stalls. Energy crashes. The medication seems to stop working.
This isn't drug failure. It's metabolic exhaustion—and it's predictable.
What's Happening
Retatrutide mobilizes stored fat through its triple-receptor mechanism. That fat still has to be converted to ATP through beta-oxidation—the pathway that breaks fat into usable energy. Beta-oxidation repeatedly uses NAD+ as an electron carrier.
The depletion spiral:
- Caloric deficit increases energy demand
- Beta-oxidation runs at high capacity
- NAD+ consumption outpaces production
- Mitochondrial efficiency drops
- Fatigue sets in, progress stalls
The Competing Demands Problem
Your NAD+ pool serves four masters simultaneously—and they all compete for the same finite resource:
| System | What It Does | Demand During Retatrutide |
|---|---|---|
| Energy production | Converts fat to ATP | Running overtime |
| DNA repair | Fixes metabolic stress damage | Increases under caloric deficit |
| Sirtuin activation | Stress adaptation and longevity | Competes with energy |
| Inflammation control | CD38-mediated immune signaling | May spike during weight loss |
When energy production dominates the pool—as it does during aggressive metabolic protocols—the other systems get rationed. Recovery slows. Stress adaptation weakens. The "wall" materializes.
The Solution: Maintain the NAD+ Floor
NAD+ support keeps all four systems from competing against a shrinking floor:
- Energy production runs without exhausting other pathways
- DNA repair continues in the background
- Sirtuin-driven adaptation stays active
- The depletion spiral never gains momentum
This is the logic behind the combination: retatrutide creates the deficit and mobilizes fat; NAD+ helps preserve the capacity to oxidize it. The biochemistry here is established—beta-oxidation requires NAD+. What has not been tested in a controlled trial is whether supplementing NAD+ during GLP-1 therapy specifically prevents the fatigue wall. The mechanistic case is strong; the clinical proof is still emerging.
For deeper understanding of NAD+ mechanisms, including the CD38/senescent cell loop that drives age-related depletion, see the complete NAD+ guide.
What NAD+ Support Is Not
NAD+ is not a weight loss accelerator. It does not make retatrutide more potent at the receptor. It is a capacity layer: useful when the metabolic machinery needs to handle higher throughput without running into fatigue, poor recovery, or compensatory cravings.
Clinical Trial Results
Retatrutide has produced unusually large weight-loss outcomes in clinical trials. The landmark NEJM 2023 study (Jastreboff et al.) reported:
| Dose Level | Weight Loss at 48 Weeks | Key Finding |
|---|---|---|
| 1 mg weekly | −8.7% body weight | Real low-dose Phase 2 arm in non-diabetic obesity |
| 4 mg weekly | −17.1% body weight | Mid-range; glucagon thresholds begin to matter |
| 8 mg weekly | −22.8% body weight | Captures most of the 12 mg effect |
| 12 mg weekly | −24.2% body weight | Top of Phase 2 range; higher side-effect burden |
The 1 mg arm matters specifically. It's a real measured dose with substantial efficacy — not a tolerance-calibration step. Its 8.7% weight loss exceeds semaglutide 2.4 mg in T2D+obesity (STEP-2 ~7.0%) and approaches tirzepatide 5 mg in non-diabetic obesity. No other compound in the GLP-1 family has direct sub-label-floor evidence at this magnitude.
The placebo-adjusted dose-response saturates between 8 and 12 mg — same shape as tirzepatide above 10 mg. Beyond 8 mg, the additional weight loss is small relative to the side-effect cost. This beginner protocol uses conservative doses (0.25–4 mg weekly) to prioritize tolerability while still producing meaningful appetite and metabolic effects. The outcome depends heavily on starting weight, metabolic health, dose discipline, protein intake, and training.
Current Status & Availability
As of May 2026, retatrutide (development code: LY3437943) is not FDA approved. The first Phase 3 readout (TRIUMPH-4, reported December 11, 2025) delivered up to 71.2 lb average weight loss — 28.7% at 12 mg over 68 weeks.⁷ Seven additional Phase 3 trials across the TRIUMPH registrational program⁶ are reading out through 2026.
Key regulatory milestones:
- Phase 2 results published in NEJM (2023)
- Phase 3 TRIUMPH-4 topline results reported December 11, 2025 (up to 71.2 lb average weight loss; 28.7% at 12 mg);⁷ additional trials reading out 2026 (NCT05929066, NCT06070792)
- FDA approval window: still pending the full Phase 3 package and regulatory review
Current non-trial access is research or grey-market, not an approved prescription pathway.
Dosing
| Parameter | Retatrutide | NAD+ |
|---|---|---|
| Dose | 0.25–4 mg total weekly | 100–250 mg |
| Frequency | Once weekly injection | 2–3× per week |
| Timing | Same day each week | Morning or mid-day |
| Route | Subcutaneous injection | IM preferred; SubQ acceptable |
| Note | Hold each dose 4+ weeks before considering titration | Slow push; split lower SubQ doses |
The peptide dosing calculator determines your exact injection volume based on reconstitution concentration. For preparation instructions, see the reconstitution guide.
Not ready to inject NAD+? Oral precursors—nicotinamide riboside (NR) at 300–500 mg daily or nicotinamide mononucleotide (NMN) at 250–500 mg daily—raise NAD+ levels more gradually but reliably. NR has the cleaner human pharmacokinetic evidence base; NMN remains a reasonable oral option. They are not the same as injectable NAD+, but they are legitimate maintenance support. See the NAD+ guide for a full comparison of repletion strategies.
Weekly Schedule (Example)
| Compound | Mon | Tue | Wed | Thu | Fri | Sat | Sun |
|---|---|---|---|---|---|---|---|
| Retatrutide | — | — | 0.25–4 mg | — | — | — | — |
| NAD+ | 100–250 mg | — | 100–250 mg | — | 100–250 mg | Rest | Rest |
Adjust to your chosen retatrutide frequency. Consistency matters more than the specific schedule.
Timeline: What to Expect
Weeks 1–4
- Adaptation — Appetite suppression begins within 48–72 hours
- Early signals — Reduced snacking, flatter glucose curves, 2–4 lb loss (some water/glycogen)
- Side effects — Mild nausea possible; smaller protein-first meals help
- Energy — May fluctuate initially; NAD+ is used to support the oxidation side of the deficit
Weeks 5–8
- Steady progress — Fat loss stabilizes at 1–2 lb/week
- Appetite — Becomes mechanical rather than emotional
- Energy — Often steadier when NAD+ support, protein, hydration, and sleep are all in place
- Challenge — May need reminders to eat enough protein
Weeks 9–12
- Consolidation — Scale progress may slow; body composition keeps improving
- Measurements — Waist circumference drops, clothes fit differently
- Metabolic state — Hunger control effortless, energy stable
- Decision point — Continue, maintain, or advance to Intermediate
Lifestyle Foundation
This protocol works on top of, not instead of, basic metabolic hygiene.
| Component | Target |
|---|---|
| Protein | 1.0 g/lb body weight daily |
| Training | 2–4 resistance sessions/week |
| Movement | Walking on non-lift days (7–10k steps) |
| Cardio | Zone 2 (conversational pace) while adapting |
| Sleep | 7–9 hours; NAD+ often improves sleep via calmer glucose |
| Hydration | 3+ liters daily; retatrutide can blunt thirst signals |
When Progress Stalls
Dose escalation should be gradual and methodical. If weight loss plateaus:
- Re-check protein, steps, hydration, electrolytes, and carbohydrate floor. A plateau with fatigue is often under-fueling, not a retatrutide-dose problem.
- If nausea, constipation, resting heart rate, chills, skin sensitivity, insomnia, or appetite collapse are still active, do not increase retatrutide.
- If the current dose has been quiet for 4+ weeks, titrate retatrutide by a small step rather than jumping dose bands.
- If fatigue is the main limiter, move NAD+ toward 250 mg per dose, improve route/dilution, or use a steady NR/NMN base before increasing retatrutide.
- Maintain the new pattern for 4+ weeks before any further titration.
Managing Side Effects
| Issue | Primary Mitigation | Secondary Options |
|---|---|---|
| Nausea | Hold dose; smaller protein-first meals | Move injection away from largest meal |
| Constipation | Fiber + fluids | Magnesium citrate at bedtime |
| Headache | Hydration | Add electrolytes |
| Resting HR increase | Hold retatrutide dose | Step back if sustained or sleep-disrupting |
| Chills/skin sensitivity | Hold retatrutide dose | Do not escalate until quiet |
| NAD+ injection sting | Slow push; dilute or split volume | IM instead of SubQ when appropriate |
| Fatigue | Improve NAD+ support, protein, carbs, sleep | Check thyroid markers if cold/fatigued |
Monitoring
| Timepoint | What to Track |
|---|---|
| Baseline | Fasting glucose, fasting insulin, HbA1c, lipid panel, blood pressure, resting heart rate |
| Weekly | Weight, waist, energy, hunger, resting HR, sleep quality |
| Bi-weekly | Progress photos (front/side/back), clothing fit |
| Week 8–12 | Repeat baseline labs; watch glucose, insulin, TG/HDL ratio, blood pressure |
What Comes Next
After 12 weeks, two paths:
Maintenance: Reduce retatrutide to the lowest effective dose, often 0.5–2 mg/week. NAD+ can move to 100–150 mg weekly or 2×/week during training blocks, high stress, or fatigue-prone periods. Oral NR/NMN can carry the daily maintenance layer.
Progress to Intermediate: Add L-Carnitine and MOTS-c to increase fat-oxidation capacity, then consider Tesamorelin if lean-mass preservation or visceral-fat focus becomes central. See Retatrutide Recomp Protocol.
Contraindications
Retatrutide:
- Personal or family history of medullary thyroid carcinoma or MEN2 syndrome
- Active pancreatitis
- Pregnancy or breastfeeding
- Severe GI motility disorders
- Pre-existing atrial fibrillation, structural heart disease, or sustained tachycardia without medical oversight
NAD+ supplementation:
- Active cancer (NAD+ supports cellular metabolism broadly—it is not selective for healthy cells)
- Severe hepatic or renal impairment
- Concurrent chemotherapy (some regimens work by depleting NAD+; supplementation may interfere)
- Heart failure, significant arrhythmia, or recent cardiac events — injectable or IV NAD+ can stress the cardiovascular system; use medical oversight or oral NR/NMN instead
Discuss with a clinician if you have a history of cancer, gallbladder disease, diabetic retinopathy, or are on glucose-lowering medications or anticoagulants that may need adjustment.
FAQ
What is the best retatrutide starting dose for beginners?
The common starting dose is 0.5 mg per week by subcutaneous injection. Lean, sensitive, South Asian, bodybuilding-cut, or tirzepatide-transition users may belong closer to 0.25 mg. Hold each dose for at least 4 weeks before increasing, and do not titrate through nausea, constipation, resting-HR elevation, chills, skin sensitivity, insomnia, or appetite collapse.
How much weight can you lose on retatrutide?
Clinical trial data showed participants losing up to 24% of body weight at 48 weeks on higher doses. A 12-week beginner protocol using 0.25–4 mg is not the same exposure window. Early losses often include water and glycogen; sustained fat loss depends on starting weight, metabolic health, dose discipline, protein intake, and training.
How does retatrutide compare to semaglutide (Ozempic)?
Retatrutide is a triple agonist; semaglutide is GLP-1-only. The pharmacology gap is wider than the receptor count suggests. Retatrutide's GLP-1 arm is intentionally softer than semaglutide's, which is why nausea profiles diverge at matched weight loss. Its GIP arm — absent in semaglutide entirely — engages adipose thermogenesis directly. Its glucagon arm actively mobilizes liver fat, while semaglutide reduces liver fat passively as a downstream consequence of weight loss. At top doses, retatrutide produced ~24% weight loss at 48 weeks (Phase 2) versus semaglutide's ~15% at 68 weeks. At microdose, the gap is wider still — retatrutide's 1 mg arm produced ~8.7% versus semaglutide 0.25 mg's near-noise-floor effect.
How does retatrutide compare to tirzepatide (Mounjaro)?
Tirzepatide is a dual GLP-1/GIP agonist. Retatrutide is GIP-dominant per milligram, with a softer GLP-1 arm and a glucagon arm tirzepatide does not have. This is not simply "more receptors layered on." It is a different signaling balance: stronger early GIP, dose-gated GLP-1 satiety, and a glucagon component that helps explain both liver-fat pressure and heart-rate sensitivity. Tirzepatide is FDA-approved with multi-year chronic safety data; retatrutide remains investigational pending Phase 3 readouts. See the retatrutide vs tirzepatide comparison for the full decision surface.
Is retatrutide FDA approved?
As of May 2026, retatrutide is not FDA approved. The first Phase 3 data (TRIUMPH-4, reported December 11, 2025) showed up to 71.2 lb average weight loss — 28.7% at 12 mg over 68 weeks.⁷ Additional Phase 3 trials are reading out through 2026, and any approval depends on the full Phase 3 package and regulatory review. Current non-trial access is research or grey-market, not an approved prescription pathway.
Why combine retatrutide with NAD+?
NAD+ supports the beta-oxidation pathway that converts mobilized fat into ATP. When retatrutide creates a deficit, stored fat still has to be burned efficiently. During significant caloric restriction, training, or rapid weight loss, NAD+ demand can rise faster than recycling keeps up. Injectable NAD+ is usually dosed 100–250 mg IM 2–3×/week for active support; SubQ can work at lower or split doses if irritation is managed.
Can I use oral NMN or NR instead of injecting NAD+?
Yes. Oral precursors—nicotinamide riboside (NR, 300–500 mg daily) or nicotinamide mononucleotide (NMN, 250–500 mg daily)—raise NAD+ levels more gradually than injections but provide reliable baseline support. NR has more completed human trials; NMN has a growing evidence base. No definitive head-to-head human study exists between them. Injectable NAD+ is better suited for acute, high-demand support; oral precursors work well as a maintenance layer, especially for users who prefer not to inject. See the NAD+ guide for a detailed comparison.
How long does it take for retatrutide to work?
Appetite suppression often begins within 48–72 hours of the first injection as the GIP and GLP-1 pathways engage. Measurable weight change in the first 4 weeks often includes water and glycogen. The 12-week window is a practical evaluation block: long enough to assess appetite control, energy, training output, side effects, and whether the current dose is doing enough.
Limitations
The mechanistic case for combining NAD+ with retatrutide is sound: beta-oxidation requires NAD+, retatrutide increases beta-oxidation, therefore NAD+ demand rises. This logic follows established biochemistry.
What remains unproven is whether NAD+ supplementation specifically prevents or reverses the fatigue wall that GLP-1 users experience. No controlled trial has tested this directly. Individual response varies—some users on GLP-1s never hit a wall; some hit it regardless of supplementation.
The NAD+ decline data (50–80% by age 60) comes from observational studies. Clinical trials of NAD+ precursors typically run 8–12 weeks. Blood NAD+ does not always reflect tissue-level changes. Long-term outcomes from chronic NAD+ supplementation remain an open question.
This protocol is built on mechanistic evidence and practical experience. It is not a controlled clinical protocol, and it should not be treated as proof that NAD+ is required for every retatrutide user.
Related Topics
- Retatrutide Guide — complete retatrutide overview
- Retatrutide Dosing Calculator — reconstitution math for 10/12/24mg vials
- Retatrutide vs. Tirzepatide — head-to-head mechanism and weight-loss differential
- Retatrutide Recomp Protocol — advanced dual-axis protocol
- GLP-1 Hub — broader GLP-1 family coverage
- Why GLP-1 Medications Make You Tired — broader GLP-1 fatigue guide covering all compounds
- GLP-1 Compounds Tool — interactive comparison with trial data on weight loss and body composition
- NAD+ Guide — why NAD+ matters for metabolic function
- MOTS-c Guide — Next-level addition: MOTS-c for fat oxidation capacity
- Mito Stack — full SS-31 + MOTS-c + NAD+ stack for comprehensive mitochondrial support during GLP-1 protocols
References
¹ Jastreboff AM, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity. NEJM 2023. NEJM 2023 retatrutide trial
² Yoshino J, et al. NAD+ Intermediates: The Biology and Therapeutic Potential. Cell Metabolism 2021. NAD+ intermediates: The biology and therapeutic potential
³ Covarrubias AJ, et al. NAD+ metabolism and its roles in cellular processes during ageing. Nature Reviews Molecular Cell Biology 2020.
⁴ Covarrubias AJ, et al. Senescent cells promote tissue NAD+ decline during ageing. Nature Metabolism 2020. Senescent cells promote tissue NAD+ decline with ageing
⁵ Camacho-Pereira J, et al. CD38 dictates age-related NAD decline and mitochondrial dysfunction. Cell Metabolism 2016.
⁶ Giblin K, Kaplan LM, Somers VK, et al. Retatrutide for the treatment of obesity, obstructive sleep apnea, and knee osteoarthritis: Rationale and design of the TRIUMPH registrational clinical trials. Diabetes Obes Metab. Published online October 15, 2025: 10.1111/dom.70209 — TRIUMPH Phase 3 program design (four trials, ~5,800 participants). TRIUMPH-4 is NCT05931367.
⁷ Eli Lilly press release, December 11, 2025. "Lilly's triple agonist, retatrutide, delivered weight loss of up to an average of 71.2 lbs along with substantial relief from osteoarthritis in first successful Phase 3 trial." investor.lilly.com — primary announcement of TRIUMPH-4 topline results. The 28.7% mean weight-loss figure at 12mg is consistent with the Lilly-announced 71.2 lb absolute figure at typical cohort starting weight.
Medical Disclaimer
The content in this protocol guide is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider before beginning any new protocol, supplement, or medication.