The top seven results of a Google search for the terms “skin” and “yoga” are all about the most superficial aspect of skin – not the health of the skin, but how it appears.

Search results promise yoga for naturally glowing skin, 6 powerful yoga asanas for glowing skin, 5 yoga poses for beautiful skin and more.

In her book Yoga Cures: Simple Routines to Conquer More Than 50 Common Ailments and Live Pain-Free, Tara Stiles offers practices for four specific skin conditions: acne, cellulite, dark eye circles, and wrinkles.

Working under the theory that stress causes acne, Stiles prescribes stressful asanas—plank, chataranga dandasana, side plank, and bow. By simply learning to stay calm through challenging asanas, Stiles asserts, practitioners will limit the negative impacts of stress, thereby reducing acne.

We can appreciate this idea, and recognize that learning to stay calm in stressful situations is a general benefit of practicing many yoga asanas. But the truth is, the development...