I came here to post this! I happen to have type 2 diabetes (won a gene lottery, I guess) and I’m on metformin party due to purported anti-aging benefits.
At the begging I had nausea issues with it but eventually switch to longterm release and I’m the side effects went away unless I don’t eat.
It truly helps with controlling the appetite and brought my diabetes under control. I don’t feel any younger but I hope the studies/discussion mentioned are truly legit.
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.
Which mitigates the damage caused by the toxic components in his evening meal. If the meal is unalterable that's a good move. But most people can do a lot more good by removing the ingredients from the meal that stress the mitochondria, particularly the excess carbohydrates and polyunsaturated fats. That same deadly duo is also responsible for atherosclerosis.
He's got an excellent diet. He's also got very solid reasoning behind metformin supplementation, having done years of research and investigation. He's a smart and respectable guy, operating in good faith with his research, so if you find yourself disagreeing with him over something trivial, it's unlikely you're right and he's wrong.
Implying that metformin is useful only to mitigate hypothetical harms from nutrition (a trivial dispute) is probably wrong.
Across various interviews, he's recommended metformin for exactly the mitochondrial effects you're talking about. He doesn't supplement on workout days to prevent disruption of the healing and recovery. Metformin isn't something that anyone should start taking blindly or blithely, as it can amplify damage from other circumstances, but it's got a clear place in Sinclair's regimen for very good reasons.
Metformin's longevity effects work on a lot of species. It's got solid science recommending it for life extension, like the other things Sinclair uses, but unless you're a doctor, or work with one to create a comprehensive life extension, health, nutrition, and fitness plan, metformin probably isn't a great idea. Sinclair is doing something similar to juggling chainsaws - it's really cool that he can do that, but it's dangerous for amateurs. Too many unknowable factors can blow up in your face.
Then again, maybe it'll be part of a standard regimen in the next decade, and the immortals are living among us.
Type 2 diabetics on metformin live 15% longer than non-diabetics. This is remarkable considering how big a health disadvantage diabetes itself is.
Metformin seems to mimic fasting somehow, by interfering with mitochondrial function.
For more information I refer you to David Sinclair's numerous discussions on this topic. He takes 1 gram of metformin per day with his evening meal.
This is not medical advice.