Why Muscle Starts Slipping After 40
It's gradual, it's predictable, and it affects far more than how you look. The good news is that it's largely within your control.
What this is
Men begin losing muscle gradually from their 30s onward, and the pace can pick up after 40 without deliberate effort to counter it. This page explains what's happening, why preserving muscle matters for metabolism, strength, and healthy aging rather than just appearance, and which factors most influence the rate of loss.
Why it happens
Age brings hormonal shifts, reduced activity, and slower recovery that tilt the balance toward muscle loss. Without resistance training and adequate protein, the body sheds muscle it isn't being asked to keep.
Common causes
Declining activity, insufficient resistance training, low protein intake, hormonal changes, poor recovery and sleep, chronic stress, and the natural aging process.
Possible paths forward
Prioritizing resistance training, the single most effective lever; ensuring adequate protein; protecting sleep and recovery; and discussing hormonal or medical factors with a provider if effort isn't translating into results. These steps support healthy aging broadly.
Questions worth asking.
These FAQs are meant to help you with common situations affecting our community - men over 40 - so when you do speak with your doctor, you have a head start. FAQs are for educational purposes only and aren't a substitute for professional medical advice.