Metformin

Evidence: ★★★★★ · Status: Off-Label, FDA Approved

💡 Did you know? Metformin, the cheap diabetes drug now trialled to extend healthy lifespan, was originally derived from the French lilac flower — used for fevers since medieval times.

In plain English

Metformin trips the same low-fuel switch (AMPK) that exercise does. Diabetics on it have outlived non-diabetics in some data. The catch for athletes: because it partly duplicates the exercise signal, it can blunt muscle and fitness gains from hard training.

How it works

Inhibits mitochondrial Complex I, raising the AMP:ATP ratio → activates AMPK. How the AMPK "burn, don't hoard" switch works → the AMPK pathway. On top of that it lowers hepatic gluconeogenesis, improves insulin sensitivity and reshapes the gut microbiome. The TAME trial is the first FDA-sanctioned trial targeting ageing itself.

Molecular target & official sources

PRKAA1 AMPK (NCBI Gene) · Metformin (PubChem CID 4091)

Watch out

GI upset (use ER), blunts exercise adaptation, B12 depletion.

Bottom line

Best for the sedentary/metabolically-at-risk; may cost gains if you train hard.

Helps with: Build Muscle & Strength · Live Longer · Gut Health

The human evidence

First-line, extensively proven for type 2 diabetes (UKPDS and decades of use). The longevity case is observational and unproven — the TAME trial is designed to test it. Do not treat the anti-aging use as established.

Stacks with

Nothing that improves it; note it can modestly blunt aerobic training adaptations and lowers B12 over years — monitor B12 and consider timing away from training.

Shares a pathway — often paired with: Statins (Atorvastatin/Rosuvastatin), Magnesium, Berberine, Iron.

Avoid combining with

Combining with heavy endurance training if peak adaptation matters; long-term B12 depletion.

Availability & where to buy

Prescription only. Prescription-only — a doctor must prescribe it. Not sold over the counter. (In Singapore: HSA-regulated.) Very cheap and subsidised for diabetes in Singapore; a generic staple.

How it works: the AMPK pathway →

Used in these protocols

Compare Metformin

Common questions

Does Metformin actually work?

Human-evidence rating: 5 of 5. Best for the sedentary/metabolically-at-risk; may cost gains if you train hard.

What are the risks or side effects of Metformin?

GI upset (use ER), blunts exercise adaptation, B12 depletion.

Is Metformin legal or approved?

Regulatory status: Off-Label, FDA Approved.