"That kind of broke my heart, said Kerr, a yoga instructor and author of "Big Yoga, a Simple Guide for Bigger Bodies." "Overweight people feel out of the loop. If you're big you might be uncomfortable in a class of 'normies,' " she said, even if the instructor is welcoming.

Kerr says some yoga teachers don't know how to adapt to bigger bodies.

"There's fitness yoga with the bendy girls in their cute little outfits, then there's the more mystical side which attracts a lot of people, then there's the plus size, which is becoming more visible," she said.

With almost two-thirds of American women either overweight or obese, according to Centers for Disease Control, and more than 15 million people practicing yoga in the United States, according to Yoga Journal, that comes as no surprise.

Kerr, who lives in Michigan, started teaching yoga 32 years ago.

"I was young and plump but not as big as I am now," she explained. "I got bigger and I needed to adapt my practice to the belly and the chest." She said while you don't have to be thin to do yoga, you do have to modify poses to suit the more curvaceous body. In her book Kerr demonstrates classic poses with a chair or a wall for extra support.

"Most people who are bigger can't start from a lying down position," said Kerr. "I'm 64. I do a modified headstand. I don't go all the way up." On the plus side she said people who are bigger don't need a lot of cushioning. Kerr said the yogic practice of pranayama, or breath control, is especially good for bigger people.