TLDR: Toe walking is likely not "unhealthy".
There is a study that classifies Idiopathic Toe Walking in children as a cosmetic deformity. It also briefly mentions adult toe walking.
"Anecdotally, adult toe walkers have a “bouncing” or “mincing” gait with less than normal heel contact during stance phase. Whether this results in any problems is unknown. The adult foot and ankle surgeons at our institution do not see patients with forefoot or midfoot problems or Achilles tendonitis with a history of persistent childhood ITW. It is quite possible that it is a physiologically benign condition. Evidence to the contrary is lacking."
There are a few things that you should consider as possible side effects to voluntarily choosing to toe walk.
Higher energy expenditure
- This study explores energy expenditure for different foot positions while walking. It found that walking on your toes does cost significantly more energy, 53-83%, low-digitigrade and high-digitigrade respectively (walking low or higher on your toes). Really fascinating study that I would recommend reading, if you are interested.
Decreased balance and therefore an increased chance to fall.
- This common argument makes sense intuitively due to lower surface area contact. However, even though ITW is commonly associated with this, there doesn't seem to be data backing up the claim that it causes decreased balance. Lessened balance could simply be a side effect that occurs in tandem with conditions such as muscular dystrophy, which are also associated with ITW.
Shorter Achilles Tendons have been associated with ITW
What came first, the chicken or the egg? Is it the loss of range of motion that causes someone to toe walk, or is it toe walking that causes the loss of range of motion?
How toe walking might cause a shorter Achilles Tendon, IF this claim has any validity. Disuse Syndrome is basically described by "Use it or lose it." Our bodies are great at adapting to change, and if it doesn't think that it needs to allocate resources for something, it will stop doing so.