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Metformin & Exercise: A Q&A with Dr. Zalzala

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Do you have concerns about Metformin erecting barriers in your exercise progress? If you do, we are here to let you know you aren’t alone. There was one research report that has hinted that Metformin has the potential to negatively impact some of the desirable effects of muscle building. However, an October 2020 study revealed that Metformin enhanced the gene expression of aging-related pathways; something that wasn’t visible in people not taking Metformin alongside exercise. This suggests that when it comes to anti-aging prospects, combining Metformin with your workouts, instead of standalone exercise, can be a good thing.

With increasing amounts of research around Metformin and exercise emerging every day, patients usually come up to me with all sorts of questions. To help break everything down nicely, I’ve answered some of the most popular questions about Metformin below.

Why can’t Metformin users gain as much muscle?

While Metformin users do make progress in terms of muscle mass, it may not be as prominent as that in non-Metformin users. There can be a few ideas to support this situation:

  1. “bulking up” is essentially cell accumulation which happens when the muscles are undergoing stress and damage. Another reason may be that Metformin boosts cell efficiency, making them less likely to sustain damage and injuries.
  2. Metformin has been considered to have properties of mTOR inhibition and also imitates calorie restriction, which leads to the encouragement of muscle repair instead of growth.

Are only diabetic Metformin users affected by this?

At the moment, this isn’t supported by the data obtained from our research.  The two latest studies (talked about here) make the claim that participants did not suffer from diabetes.

Can consuming Metformin purely for longevity purposes create issues in gaining muscle mass? Will the muscles still get toned?

Metformin consumption should not pose a problem in those looking to build muscle mass for health reasons.

However, if you are interested in “bulking up” for specific performance goals or competitive reasons (such as those for bodybuilding competitions or marathons), then it would be better to avoid Metformin till the time you’ve hit your goals, or until after the competition.

Should IR Metformin be used if I work out a lot? What is the difference between the effects of ER and IR Metformin?

In simple, non-medical terms, choosing to use IR or ER Metformin is mainly a matter of personal choice. Turning for guidance to one of most Metformin experts, Dr. Nir Barzilai reveals that Extended Release (ER) Metformin will be put to use during the TAME trial.

At AgelessRx, we mainly prescribe ER Metformin for two reasons:

  1. You will only need to take it once daily, which is easier to remember.
  2. It’s much gentler on the stomach than IR Metformin and causes lesser cramps.

There could be an argument that IR Metformin provides greater peak Metformin levels. But the effects of that over longevity results aren’t very well known at the moment.

In my medical opinion, looking at it from a medical viewpoint, I think I would only recommend IR over ER if someone wants to quickly flush it from their system for workouts. But even in that case, it’s possible for Metformin to remain in the bloodstream for a while.

Are there any specific exercises that should be avoided while using Metformin?

All types of exercise should be okay; however, I usually suggest that patients skip Metformin when training for competitions and marathons.

Does science explore the effects of Metformin on regular cardiovascular activities?

Yes, and there’s still more investigation needed regarding this. A study conducted in 2010 hinted that Metformin at high doses (much greater than what we prescribe at AgelessRx) may lead to a reduction in the benefits gained by exercise. The reason for this may be because Metformin lowers oxidative stress, which is the kind of stress that boosts aerobic function.

The effects of lowered or skipped doses on this are not clear at the moment. However, at AgelessRx, we generally recommend that hardcore athletes and fans of strenuous exercise shy away from Metformin until more information becomes available.

Can I start taking Metformin again if I skip a few doses or discontinue using it for a while?

Skipping a few doses every now and then should not have any negative effects and you can safely resume prescribed doses. However, if you have skipped Metformin for a few months or longer, it would be better to have a 10-14 day ramp-up period to avoid gastrointestinal issues.

I hope you got the answers to some of your questions about Metformin and exercise. Until next time!

Dr. Z


The Rx Review is an independent fitness website, reporting on the Sport of Fitness, functional fitness news, The CrossFit Games, health and diet related information, and also provides reviews on sports performance products.