It seems to mimic exercise, too. Not just fasting.
Metformin has numerous other effects: it reduces carbohydrate absorption in the gut, changes the gut microbiome, increases insulin sensitivity, reduces the liver's conversion of proteins to glucose, changes the way proteins accumulate in the brain (thereby making dementia less likely), etc.
When you're on metformin you can feel the physiological stress. It's like a mild attack on your whole body, a persistent slight discomfort. It's like a very mild poison.
Metformin has numerous other effects: it reduces carbohydrate absorption in the gut, changes the gut microbiome, increases insulin sensitivity, reduces the liver's conversion of proteins to glucose, changes the way proteins accumulate in the brain (thereby making dementia less likely), etc.
When you're on metformin you can feel the physiological stress. It's like a mild attack on your whole body, a persistent slight discomfort. It's like a very mild poison.