Why is the dark side so harmful to the user's body while the light side does almost no damage?

Title.

I always assumed that it's some kind of metaphor because chronic use of the Dark Side involves chronic use of anger, hatred, malice, vengeance etc. and Sith Lords like Sidious constantly give into these dark emotions to empower themselves, and in real life, holding onto said emotions is unhealthy and toxic because they weaken the immune system and deplete your body's energy levels, leaving you more vulnerable to illnesses and shit. The Light Side, especially the Jedi Order of the PT era, have vowed to sparingly feel their emotions, including anger and hatred, so their bodies don't get degraded.

I actually think even using the light side of the Force excessively can wear the body down. According to the Bane Trilogy flesh and bone lacked the strength to withstand the unimaginable power of the Force:

Dynasty of Evil wrote:Flesh and bone lacked the strength to withstand the unfathomable energy unleashed by the Force. The unquenchable fire of the dark side was consuming him, devouring him bit by bit. After decades of focusing and channeling its power, his body was beginning to break down.

If using the dark side is analogous to taking PEDs then using the light side in excess can be equated to overtraining. And this is a pretty common trope in fiction: Aang's body wore down from excessive use of the Avatar State and Kenshin couldn't use Hitsen Mitsurugi-ryu any more by the end of the series. Probably one of the reasons Jedi encourage moderation.

Plagueis describes the dark side as a disease no true Sith wishes to be cured of. It's associated with death, entropy and destruction which explains the corruption it has on organics.

The Light Side in its purest form is actually healing. The reason Force Light is so powerful against Sith is that is effectively a cure for the disease of the Dark Side. We've also seen repeatedly that the healing effects of the light side are pound for pound much stronger than their dark side equivalents e.g Cade Skywalker.

i think the idea that the dark side is a drug is almost perfect tbh. its very addicting, makes u believe in things that arent true, ur emotions are almost always out of ur control if ur a noob, it destroys one's mind often times, and breaks down their bodies after some time. these effects are made worse the more the dark side is used. does explain why so many of them want to find a cure, but like plagueis said, they never really want to let go anyhow. i figured the light side was literal focus and mental stability. the more one has of those two, the more attuned to the light side they are. makes me wonder if the reason why cold people like dooku excelled on it so much. the logical thinking, and lack of emotions mustve really helped him out. i assume the same could somewhat be said about exar kun, but he was younger and much more careless about his emotions that dooku was.