High heels distribute your weight unevenly and force the arch of your foot into an unnatural position. This impacts your gait as well as the way the force from walking and other activity is distributed–putting strain on your arch and causing tearing and inflammation.
High heels also typically fail to support your heels with cushioning, meaning that the pad of your heel is pressed into a hard, unsteady surface. And that’s not all. Even not wearing high heels can cause plantar fasciitis (if you wear them regularly enough!) Since high heels leave you with a weakened arch, suddenly switching to more supportive shoes after chronic high heel use still leaves you with an arch that can’t as effectively absorb impact or support your weight.