Metformin for non-diabetics — does it cancel out your exercise benefits?
So I’ve been taking metformin 500mg twice daily for about 6 months now (I’m not diabetic, just using it for longevity/anti-aging purposes based on my functional medicine doc’s recommendation). I’m 38F and pretty active – I do CrossFit 4x a week and some running on off days.
Anyway, I recently came across some research suggesting that metformin might actually blunt the benefits you get from resistance training? Something about it interfering with mTOR signaling which is important for muscle adaptation. This is kind of freaking me out because I’ve been working really hard in the gym and don’t want to be canceling out my gains.
Has anyone else looked into this or experienced it? I feel like my strength progress has been slower than I’d expect given my consistency, but that could also just be other factors (sleep, stress, etc). I’m wondering if I should cycle off metformin on training days or just stop it altogether.
Would love to hear if anyone has experience with this or knowledge about the timing – like if taking it at different times of day makes a difference?
Yeah I’ve definitely read about this concern. I’m 45M and was on metformin for about a year before switching focus more to exercise-based interventions. From what I understand, the interference is real but the magnitude is still being debated. Some studies show significant blunting of muscle protein synthesis, others show minimal impact.
What I ended up doing was taking metformin only on rest days and skipping it on heavy training days. No idea if that’s optimal but it made me feel better about it psychologically lol. Honestly though, you should probably discuss with your doc whether the longevity benefits outweigh the potential training interference for YOUR specific goals.
I actually stopped metformin for this exact reason. I’m very into bodybuilding and the research was concerning enough that I didn’t want to risk it. That said, my uncle takes it and still made great progress in his strength training at 60 years old, so YMMV.
Jake mentioned taking it on rest days only – that’s one approach. I’ve also seen people suggest taking it far away from workout windows, like if you train in the morning, take your dose in the evening. The mTOR suppression is temporary, not permanent, so timing might matter more than we think.
This is such a tough one because metformin has SO many benefits beyond just glucose control. The autophagy promotion, the AMPK activation, potential cancer prevention, etc. I take 1000mg daily and honestly haven’t noticed my workouts suffering but I’m more into Zone 2 cardio and yoga rather than heavy lifting, so maybe I wouldn’t notice the same effects you’re concerned about?
Tbh I think it depends on what your primary goal is. If building muscle is top priority maybe metformin isn’t the right tool right now. But if longevity is the main focus and you’re okay with slightly slower strength gains, might be worth continuing?