GLP-1s, Peptides, and The Trillion-Dollar Health Revolution (Alex Karnal)
Alex Karnal — biotech investor of 20 years — calls 2025 the single most exciting year of his career. GLP-1s are the proof point for a once-in-a-lifetime trillion-dollar revolution in public health. He frames a 'Health Stack' (5 layers, offense + defence) where every layer already has medicines that work; the gap isn't science, it's distribution and adoption. Three 2025 discoveries: people optimise for tolerability not weight-loss-maximisation; >50% of new GLP-1 joiners come direct-to-consumer; compounded GLP-1s prove massive price elasticity.
Key points
- GLP-1s already trending past $100B/year and now established as the proof-of-concept for proactive medicine. Beyond weight loss, they cut pre-diabetic → diabetic conversion by 94% (Lilly data), reduce heart attack and stroke risk, protect kidneys, and have early signal on addiction (alcohol, drugs).
- Karnal's broader 'Health Stack' frame: five layers, all currently addressable with existing medicines if people are proactive. (1) Lipid optimisation — statins, PCSK9 inhibitors. (2) Cardiometabolic — GLP-1s. (3) Neurocognitive — anti-amyloid medicines (next major Lilly readout later this year on early-stage Alzheimer's). (4) Inflammatory — driven by ultra-processed food. (5) Blood pressure.
- 'The gap is not needing more medicines. It's pointing those medicines at the impact they can have.' Lifespan curves have been roughly flat since the antibiotics + vaccines + hygiene era. Most of the science is already done; the bottleneck is now distribution, adoption, behaviour.
- Discovery 1 (2025): Wall Street has been over-indexed on weight-loss-maximisation as the GLP-1 differentiator. Real consumer demand is for tolerability + stability, not the biggest dose. Going up the dose curve trades diminishing weight-loss returns for compounding side effects.
- Discovery 2 (2025): Lilly Direct (D2C distribution) crossed >50% of new joiners. Categorical shift from rep-detailing-doctors model to consumer-pull. Implication: pharma economics are rerouting through what looks more like Hims-and-Hers than legacy pharma sales-force structure.
- Discovery 3 (2025): Compounded GLP-1s revealed massive price elasticity. At ~$200-250/month (vs $400-500 for branded), 15-20% of the market that couldn't be captured through scripts flowed through Hims, Hers and other sources. Patients will accept clinical-trial-less compounded versions because the perceived value is so high.
- Lilly Direct + price elasticity together = pharma is becoming a consumer software-shaped business. The TAM of 'people willing to be proactive about their health' is enormous and previously unreachable through the traditional channel.
- On lifespan inflection: combining all five Health Stack layers proactively could add an extra decade of expected lifespan. The medicines exist. The question is whether the system delivers.
- On anti-amyloid medicines: Karnal expects Lilly's next readout to show that hitting amyloid plaques EARLY (before significant accumulation) dramatically protects against developing Alzheimer's. Major potential category if confirmed.
- The investor framing: 'There's money on the line here. This isn't just reading something and trying something — it comes out on a scoreboard.' Karnal has been right about GLP-1 adoption exceeding consensus.
Notable quotes
2025 was probably the single most exciting year in my entire 20-year journey in biotech.
GLP-1s are the first commercial proof that we are ready for what I think we'll look back on as a once-in-a-lifetime trillion-dollar revolution in public health.
The gap is not needing more medicines. It's pointing those medicines at the impact they can have.
What people really want is something that gives them a health advantage but is incredibly tolerable.
More than half of the new people joining are coming in directly.
Themes
- GLP-1s as the proof-of-concept for proactive medicine
- The Health Stack — five layers, existing medicines, distribution gap
- Pharma's shift to direct-to-consumer
- Compounded GLP-1s and the price-elasticity proof point
Mentioned
Ideas
- The Health Stack (5 layers)
- Tolerability over weight-loss-maximisation
- Direct-to-consumer pharma distribution
- Compounded GLP-1 price elasticity
- Anti-amyloid medicines
- PCSK9 inhibitors
- Statins
- Pre-diabetic → diabetic 94% reduction
- Lifespan inflection thesis
- Trillion-dollar health revolution
- Inflammatory health driven by ultra-processed food
- Lifestyle bundle (lipid + cardiometabolic + neurocognitive + inflammatory + BP)