Advanced Lean Stack across Europe

The Advanced Lean Stack pairs our RETATRUTIDE 32 pen with our NAD+ 1000 pen. “Advanced” is a marketing word: retatrutide reaches one receptor more than tirzepatide and its Phase 2 result was larger, but its programme is unfinished and no regulator has authorised it. You usually arrive from the weight-loss goal, weighing it against the Lean Stack.

Retatrutide: three receptors, one Phase 2 trial in print

Retatrutide (development code LY3437943) activates the GIP, GLP-1 and glucagon receptors. Semaglutide acts on GLP-1 alone, tirzepatide adds GIP, and retatrutide adds glucagon on top of both (what is retatrutide?). The glucagon receptor activity is the genuinely new element: a different pathway, not a stronger version of the previous ones.

The trial that drives the interest is a 48-week, double-blind, randomised, placebo-controlled Phase 2 study in adults with a body-mass index of 30 or higher, or 27 to under 30 with at least one weight-related condition. It reported substantial reductions in body weight, around 24% at the highest dose studied (Jastreboff AM, Kaplan LM, Frías JP et al. Triple–Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. N Engl J Med 2023. PMID 37366315). A later systematic review and meta-analysis of randomised trials reached broadly consistent conclusions on weight and metabolic markers (Pasqualotto E et al. Effects of once-weekly subcutaneous retatrutide on weight and metabolic markers. Metabol Open 2024. PMID 39318607). Gastrointestinal adverse events were the most common, dose-related, and the reason the trial escalated the dose over time rather than starting at the target. We do not publish a dosing schedule.

Still in Phase 3, and authorised nowhere

A Phase 2 trial establishes a signal and informs dose selection. It is not the basis on which a medicine is authorised. Retatrutide’s Phase 3 obesity programme, TRIUMPH, is registered and its design is published (Giblin K 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 2026. PMID 41090431). The lead obesity study, TRIUMPH-1 (NCT05929066), enrolled 2,335 participants; the registry lists it as completed in April 2026, and as of our review no results have been posted there or published in a peer-reviewed journal. Retatrutide holds no marketing authorisation from the EMA, the FDA or any comparable regulator. It is investigational, which is a real and specific status: in active development, and neither approved nor abandoned.

That is the sharpest difference from tirzepatide. An authorised tirzepatide medicine exists and a clinician can prescribe it; no authorised retatrutide medicine exists anywhere. The regulatory position of everything we sell is set out at why these compounds are not EMA-authorised.

NAD+: the same coenzyme, the same thin evidence

NAD+ is not a peptide. Nicotinamide adenine dinucleotide is a coenzyme in cellular energy metabolism that takes part in redox reactions rather than binding a receptor (what is NAD+?). The human trial literature is mostly about the oral precursors NMN and nicotinamide riboside, because NAD+ itself is large and poorly absorbed by mouth. Those trials show that supplementation raises blood NAD+ (Conze D et al. Safety and Metabolism of Long-term Administration of NIAGEN (Nicotinamide Riboside Chloride) in a Randomized, Double-Blind, Placebo-controlled Clinical Trial of Healthy Overweight Adults. Sci Rep 2019. PMID 31278280). A meta-analysis of randomised NMN trials at 250–2,000 mg per day reported no significant change in fasting glucose, insulin, HbA1c or lipids (Chen F et al. Effects of Nicotinamide Mononucleotide on Glucose and Lipid Metabolism in Adults. Curr Diab Rep 2024. PMID 39531138). Levels rise; clinical endpoints do not follow reliably. NAD+ holds no marketing authorisation for this use. Its position here is the same as in the Lean Stack: included for its own reasons, not as an amplifier for the incretin pen.

Where the evidence for the pair stops

No published trial has tested retatrutide and NAD+ together, and retatrutide’s own evidence is not yet complete. Each pen in this set is the same product sold on its own page; nothing is mixed or co-formulated, and we do not suggest how to sequence or combine them. Our pens are independently tested per batch for identity, purity and sterility; the certificate for your lot is reachable from the QR code on the pen, and every batch certificate is published at /coa.

Advanced Lean Stack or Lean Stack?

The two sets differ in one pen. The question is which incretin compound you want, and the honest framing is a comparison of evidence stage rather than of headline percentages.

	Lean Stack	Advanced Lean Stack
Incretin pen	TIRZEPATIDE 60 (dual GIP/GLP-1)	RETATRUTIDE 32 (triple GIP/GLP-1/glucagon)
Evidence stage	Completed Phase 3, two indications	Phase 2 published; obesity Phase 3 results not yet published
Authorised medicine exists?	Yes (Mounjaro); our pen is not it	No, anywhere

Comparing retatrutide’s Phase 2 figure against tirzepatide’s Phase 3 figures is comparing results at different stages of maturity, which is fair only if the difference in stage is stated alongside it. The retatrutide vs tirzepatide page does that in detail.

Who typically chooses the Advanced Lean Stack

You are usually someone whose main interest is the weight-loss goal. You have read the retatrutide Phase 2 paper, you understand that it is a Phase 2 paper, and you want the triple agonist specifically for its glucagon receptor activity rather than the authorised-compound route. If a completed programme and an existing authorised medicine matter more to you than receptor coverage, the Lean Stack is the more conservative choice. Either set ships from our Czech dispatch point in cold-chain packaging. A RETATRUTIDE 64 pen is also listed on its own for anyone who wants the higher strength rather than this pairing.