Metformin
most data
The Dose Guy’s verdictSep 1, 20266 sources
If you want a metabolic floor under everything else you do, metformin is still the answer. The most proven metabolic insurance policy in medicine, oral, decades of safety data, a legitimate first-line if you are prediabetic or carrying metabolic risk. It is not a weight-loss drug, a few kilos over a couple of years that come back when you stop. If you want the scale to move hard, you want tirzepatide or retatrutide.
What it is
An oral biguanide and the most prescribed diabetes drug on Earth. Metformin works mostly by telling the liver to stop dumping glucose you do not need, while improving how your cells respond to insulin. The result is lower blood sugar, better insulin sensitivity, and a modest reduction in appetite that some people notice and others do not. It activates AMPK, the same energy-sensing pathway the exercise-mimetic crowd chases with exotic compounds, except metformin does it in a pill with a sixty-year track record.
The weight effect is real but secondary. People lose a few kilos compared to placebo across the trials, and they regain them when they stop. This is not the territory of the GLP-1 agonists like tirzepatide and retatrutide, where the appetite switch turns off and the weight comes down hard. The longevity angle, that metformin slows aging itself, is the reason half the biohacker community takes it, but that hypothesis is still being tested. What the evidence actually supports is diabetes prevention and glucose management. Everything else is extrapolation from epidemiology and mechanistic optimism.
What the research shows
The evidence base is enormous for diabetes and glucose, thin for weight loss as a primary endpoint, and still unresolved for longevity:
Realistic protocols
Start at 500 mg once daily with dinner. Give it a week, then move to 500 mg twice daily with meals if the gut tolerates it. Most people land at 1,000 to 1,700 mg daily. The extended-release formulation cuts the GI complaints and is worth asking for if the standard tablets are rough. Take it with food, always.
Supplement B12. This is not optional on a long run. The depletion is slow, cumulative, and causes the kind of neuropathy that gets blamed on aging rather than the pill. A basic B12 supplement or a yearly blood level handles it.
The titration is GI-limited, not effect-limited. Metformin’s glucose benefit plateaus well before the max dose, so pushing through stomach trouble to hit 2,000 mg is rarely necessary. If 1,000 mg keeps your fasting glucose where you want it, stay there.
Alcohol is fine in moderation, but heavy drinking and metformin both stress lactate clearance, and the combination on an empty stomach can drop your blood sugar. The practical version: a couple of drinks with food is not the problem. Binge drinking on metformin without eating is.
Side effects
The side profile is mild by any standard, and most of it lives in the gut:
