When you knowingly and willingly begin to compromise your health, your "fitness" plan has gone too far. It's ironic really. You adopt a training or diet plan to lose fat, build muscle, get strong, or extend your life, then things go sideways and your fitness plan begins to wreck your fitness.
Most of the time, there are deeper psychological issues at work here. But for dedicated folks who love to train, it can be a fairly easy trap to fall into. Some examples:
A fat loss diet turns into borderline anorexia. This is often associated with an obsession with scale weight. The desired outcome gets twisted: the goal becomes a smaller number on the scale instead of the sexy look of a healthy reflection in the mirror.
Your pursuit of abs leaves you looking like a malnourished meth addict. There's even something called "exercise induced bulimia." That's where the person doesn't purge by throwing up food, but instead tries to purge every calorie he or she eats through excess exercise, usually cardio. (Yeah, that ends badly.)
The obsessive pursuit of PRs leaves you busted up and unable to do real-life things, like walking up stairs or getting out of the car without psyching up first. Strength is awesome, but true 1RM attempts are largely unnecessary outside of a competition.
The pursuit of size leaves you fat or playing a reckless game with bodybuilding drugs.
A love of running leaves you beat up and constantly hurt instead of feeling good.
When a trendy diet starts doing you more harm than good. The key to this one is that you KNOW deep down it's not working for you anymore, but the idea of it is so compelling, so "scientifically backed," or is such an ego-inflating virtue signal that you can't give it up.
The Competitor's Dilemma
What about athletes? Christian Thibaudeau recently wrote on the T Nation Facebook page, "Every single competitive sport is bad for the body when done at the level required to compete at the highest level."
For those folks, it's not really about fitness. It's about winning. But you're probably not an elite or pro level athlete. And damaging your body probably isn't putting retire-at-40 money into your bank account.
Health First
The lesson here? Health first. Whenever health falls down to the number two or number three spot, or disappears altogether, your fitness plan, well, isn't about fitness anymore.