| 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 that engages three receptors — GIP, GLP-1, and glucagon — at very different fractions across the dose range:
| Dose | GIPR (obese / lean) | GLP-1R (obese / lean) | GCGR (obese / lean) |
|---|---|---|---|
| 0.25 mg | 21% / 24% | 2% / 3% | 0.3% / 0.4% |
| 0.5 mg | 35% / 39% | 4% / 5% | 0.6% / 0.7% |
| 1 mg | 51% / 56% | 8% / 10% | 1.2% / 1.4% |
| 2 mg | 68% / 72% | 15% / 18% | 2.3% / 2.8% |
| 4 mg | 81% / 84% | 26% / 30% | 4.5% / 5.4% |
| 8 mg | 90% / 92% | 44% / 49% | 9% / 11% |
| 12 mg | 93% / 94% | 53% / 58% | 13% / 15% |
Numbers are receptor engagement percentages — the fraction of each receptor type bound and signaling at chronic steady state. Obese column anchored at the Jastreboff Phase 2 cohort (~109 kg, BMI 37); lean column at ~75 kg metabolically healthy.
Two patterns matter for the dose decision.
First, GIPR engages fast. By 1 mg, the GIP receptor is already in the working range — held continuously every hour of every week, instead of in the brief meal-time pulses native physiology produces. That's the receptor doing the direct fat-cell work (insulin efficiency, adipose thermogenesis), and it is mostly online before the appetite arm (GLP-1R) has climbed. Even at 1 mg, retatrutide is a GIP-dominant drug; the GLP-1 arm is softer than pure GLP-1 agonists, and the glucagon arm climbs proportionally with dose.
Second, the lean and obese columns sit close. The per-mg exposure shift between phenotypes is real but modest. The larger phenotype difference is downstream: the same engagement produces a measurably stronger cardiovascular response in lean cohorts — higher resting heart-rate sensitivity, sharper β-OHB rise, faster onset of skin sensitivity and chills. Lean, sensitive, South Asian, or tirzepatide-transition users typically start at 0.25–1 mg with 4+ week holds, not because the receptor engagement is different at the same dose, but because the body responds more loudly to the same engagement.
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 emerge: resting heart-rate elevation, chills, skin sensitivity, insomnia, and a more catabolic feel.
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.
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, and 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 a major hub for NAD+ recycling and the canonical site for nicotinamide clearance. You're concentrating fat-oxidation demand on an organ that already runs heavy NAD+ traffic. The math is tighter with retatrutide because the glucagon arm concentrates demand on hepatic NAD+ recycling — load that other GLP-1-class drugs distribute 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.
What looks like the medication losing effectiveness is usually 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, and 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 because of where it lands on the receptor map. At 1 mg, retatrutide's GIP receptor engagement is already in the working range — held continuously every hour of every week, instead of in the brief meal-time pulses native physiology produces. The 8.7% weight loss reflects that engagement. It is not a tolerance-calibration step. 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. 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) showed an average 28.7% weight loss at 12 mg over 68 weeks — approximately 71 lb at the cohort's starting weight.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 (28.7% mean weight loss at 12 mg / 68 weeks, approximately 71 lb at cohort starting weight);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 | 50–100 mg (EoD) or 100–200 mg (2–3× weekly) |
| Frequency | Once weekly injection | Every other day, or 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 | First-phase loading for users with depleted baseline |
The peptide dosing calculator determines your exact injection volume based on reconstitution concentration. For preparation instructions, see the reconstitution guide.
The injectable NAD+ range above is a loading-phase convention. It applies when there is reason to expect a depleted baseline — age 50+, recovering from chronic illness or a post-viral state, prolonged caloric deficit, chronic stress, or symptomatic fatigue at protocol start. After 4-8 weeks of loading, the dose typically steps down to 2× weekly or transitions to oral precursors for ongoing support. Users without depletion markers can skip the loading phase and operate on oral precursors from the start.
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 than injections. 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+ | 100–200 mg | — | 100–200 mg | — | 100–200 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 consistent for most users, 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 | At least 1.6 g/kg body weight daily, 3-4 meals |
| 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 standard starting dose is 1 mg per week by subcutaneous injection — the lowest arm directly measured in the Phase 2 obesity trial. Lean, sensitive, South Asian, bodybuilding-cut, or tirzepatide-transition users typically belong closer to 0.5 mg; further down at 0.25 mg for lean South Asian phenotype with high cardiac sensitivity. 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. See the retatrutide dosing calculator for the full ladder.
How much weight can you lose on retatrutide?
Phase 2 means at 48 weeks (non-diabetic obesity):
| Dose | Mean weight loss |
|---|---|
| 1 mg | −8.7% |
| 4 mg | −17.1% |
| 8 mg | −22.8% |
| 12 mg | −24.2% |
Phase 3 TRIUMPH-4 (68 weeks, obesity + osteoarthritis cohort): 28.7% mean at 12 mg.⁷
These are averages, not ceilings. Trial responder distributions show meaningful spread — about 1 in 5 participants on the 12 mg arm in Phase 2 lost ≥30%; some lost much less. A 12-week beginner protocol using 0.25–4 mg is a different exposure window than the 48- or 68-week trials. 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. The structural difference shows up most clearly at sub-trial-floor doses: at 1 mg, retatrutide's GIP and GLP-1 arms are both already in the working range, and the glucagon arm has no analog in semaglutide at any dose.
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 28.7% mean weight loss at 12 mg over 68 weeks — approximately 71 lb at the cohort's starting weight.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.