Triple agonist (GIP/GLP-1/glucagon receptor)18 PubMed Citations

Retatrutide Supplement Protocol

Evidence-based nutrient depletion risks and supplement recommendations for LY3437943 users.

Brand Names
LY3437943
Mechanism

Activates GIP, GLP-1, and glucagon receptors simultaneously, producing greater weight loss than single or dual agonists. Glucagon receptor activation increases energy expenditure and hepatic glucose output; GIP and GLP-1 activation enhances insulin secretion, suppresses appetite, and slows gastric emptying.

FDA Status

Phase 3 clinical trials (TRIUMPH program, as of April 2026). Not yet FDA approved.

Common Doses
1mg weekly SC
4mg weekly SC (initial dose 2mg)
8mg weekly SC (initial dose 2mg)
12mg weekly SC (initial dose 2mg)

Nutrient Depletion Risks

9 nutrients affected by Retatrutide

Vitamin DHIGH

Reduced caloric intake leads to lower dietary vitamin D. Rapid fat loss releases stored vitamin D but overall status often declines over 6-12 months.

SupplementVitamin D3 (cholecalciferol)
Dose2,000-5,000 IU/day depending on blood levels
MonitorCheck 25(OH)D at baseline, 3 months, 6 months, then annually
IronHIGH

Reduced food intake, especially red meat. GI side effects may further impair absorption.

SupplementIron bisglycinate (better tolerated with GI effects of GLP-1)
Dose18-36mg/day if deficient (only with confirmed low ferritin)
MonitorCheck ferritin + transferrin saturation at baseline and every 6 months
Do NOT supplement iron without confirmed deficiency. Take separately from calcium and coffee.
Vitamin B12MODERATE

Delayed gastric emptying may impair B12 absorption. Reduced meat intake compounds risk.

SupplementMethylcobalamin sublingual
Dose1,000-2,500 mcg/day sublingual
MonitorCheck serum B12 + MMA at baseline and 6 months
CalciumMODERATE-HIGH

More than 60% of GLP-1RA users consume below estimated requirements for calcium. Rapid weight loss accelerates bone turnover.

SupplementCalcium citrate (better absorbed than carbonate, especially with reduced stomach acid)
Dose500-1,000mg/day in divided doses
MonitorCheck serum calcium, PTH. Consider DEXA at baseline if high risk.
MagnesiumMODERATE

Reduced food intake. GI side effects (nausea, diarrhea) may further deplete.

SupplementMagnesium glycinate (least GI disruption)
Dose200-400mg elemental magnesium/day
MonitorCheck RBC magnesium (serum is unreliable)
ProteinHIGH

Appetite suppression leads to inadequate protein intake. Lean mass loss is a major concern with rapid weight loss. Glucagon receptor activation may promote protein catabolism, compounding the risk.

SupplementProtein supplementation (whey, collagen, or plant-based)
Dose1.2-1.6g protein per kg ideal body weight daily
MonitorTrack prealbumin, albumin. Monitor lean mass via DEXA if available.
Thiamine B1MODERATE

Thiamine deficiency increases over time with prolonged caloric restriction. Glucagon-driven glycogenolysis may increase thiamine utilization.

SupplementThiamine HCl or benfotiamine
Dose50-100mg/day
MonitorCheck thiamine levels if symptoms (fatigue, neuropathy, confusion)
PotassiumLOW-MODERATE

GI side effects (vomiting, diarrhea) can deplete electrolytes

SupplementDietary potassium preferred. Supplement cautiously.
DoseDietary emphasis first. Supplement only if confirmed low.
MonitorCheck basic metabolic panel
Dangerous if on ACE inhibitors or renal impairment
Omega 3MODERATE

Reduced dietary intake of fatty fish due to appetite suppression

SupplementEPA/DHA fish oil or algae omega-3
Dose1-2g EPA+DHA/day
MonitorCheck omega-3 index if available

Essential Supplement Stack

Priority-ranked supplements based on depletion evidence

Vitamin D3With largest meal
2,000-5,000 IUHIGH
Protein powderMorning or post-workout
20-40g/dayHIGH
Magnesium glycinateBefore bed
200-400mg elementalHIGH
Vitamin B12 sublingualMorning
1,000 mcgMODERATE
Calcium citrateWith meals, split doses
500mgMODERATE

Recommended Additions

Additional supplements based on individual risk factors

Omega-3 EPA/DHAWith meal
1-2gMODERATE
Iron bisglycinateEmpty stomach or with vitamin CRequires blood test confirmation
18-36mgONLY IF DEFICIENT
Vitamin K2 MK-7With vitamin D
100-200 mcgLOW-MODERATE
Thiamine (B1)Morning
50-100mgLOW-MODERATE

Lab Monitoring Schedule

Recommended testing timeline while on this medication

Baseline
25(OH)DB12MMAFerritinTransferrin satCBCCMPAlbuminPrealbuminHbA1cLipid panelThiamine (if symptomatic)
3 Months
25(OH)DFerritinB12AlbuminCMP
6 Months
Full panel repeat
12 Months
Full panel + DEXA if available

Every 6-12 months depending on results

Drug Interactions

5 known interactions to monitor

MetforminMODERATE

Both reduce B12 absorption. Combined use increases B12 deficiency risk significantly.

ActionMonitor B12 more frequently. Consider higher B12 supplementation (2,500 mcg sublingual).
PPIs (omeprazole, etc.)MODERATE

Further reduces B12 and magnesium absorption

ActionConsider sublingual B12 and magnesium glycinate
InsulinHIGH

Retatrutide's triple agonism (including glucagon) may cause unpredictable glucose effects requiring insulin dose adjustment

ActionMedical supervision required. More frequent glucose monitoring.
WarfarinMODERATE

Vitamin K2 supplementation may affect INR

ActionMonitor INR if adding K2
Thyroid medications (levothyroxine)MODERATE

Delayed gastric emptying may alter levothyroxine absorption

ActionTake thyroid meds 60 min before any meal, on empty stomach

Retatrutide-Specific Notes

Important considerations unique to this medication

retatrutide specific

Retatrutide is a TRIPLE agonist (GIP/GLP-1/glucagon). The glucagon receptor activation may increase metabolic rate but also accelerates glycogenolysis and could affect blood sugar more aggressively than pure GLP-1 agonists. Phase 2 trials showed weight loss of 24.2% at 48 weeks with 12mg dose — the highest of any GLP-1 class drug tested to date. This aggressive weight loss amplifies all nutrient depletion risks. Monitoring should be more frequent in the first 3-6 months.

glucagon unique risks

Glucagon agonism promotes hepatic glucose output, lipolysis, and protein catabolism. This unique mechanism means retatrutide users may face: (1) higher protein/lean mass loss risk than pure GLP-1 users, (2) greater B-vitamin utilization from accelerated energy metabolism, (3) potential blood glucose fluctuations requiring closer monitoring in diabetic patients.

clinical trials summary

Phase 2 obesity trial (PMID: 37366315): 338 adults, 48 weeks, weight loss up to -24.2% at 12mg. Phase 2a MASLD substudy (PMID: 38858523): 98 participants, liver fat reduction of -82.4% at 12mg. Body composition substudy in T2D (PMID: 40609566): significant fat mass reduction. TRIUMPH Phase 3 program (PMID: 41090431): 4 trials, 5800+ participants evaluating obesity, OSA, and knee OA.

gi considerations

Nausea, vomiting, and diarrhea are common during dose titration. Choose supplement forms that minimize GI distress: sublingual B12, magnesium glycinate (not oxide), iron bisglycinate (not sulfate), calcium citrate (not carbonate).

timing recommendations

Take fat-soluble vitamins (D, K2, E) with the largest meal. Take iron separately from calcium and coffee (2+ hours apart). Take magnesium before bed. Take thyroid medications 60+ minutes before retatrutide injection day meal.

Evidence Citations

18 PubMed-indexed studies referenced

Add this protocol to your profile

Your Daily Intelligence and Ask Dose will be personalized for the Retatrutide protocol, including nutrient depletion alerts and interaction warnings.

Sign in required. Your health data stays encrypted and private.

Medical Disclaimer

This protocol is for educational purposes only and is not medical advice. Supplement recommendations are adjunctive support, not replacements for prescribed medication. Always consult your prescribing physician before adding supplements to your Retatrutide regimen. Individual needs vary based on health status, diet, and concurrent medications. Scan Dose is not affiliated with any pharmaceutical manufacturer.

Scan Dose does not sell supplements or accept affiliate commissions. All content is independently researched.