LeAnn Rimes in Cabo San Lucas, Mexico
and her trainer want critics of her lean frame to know one thing: she's fine, thank you very much.
tells PEOPLE the "hoopla about my body" – which intensified after photos of her in a bikini
during her recent honeymoon emerged – has been hurtful.
"For someone like me who is healthy, who works hard for my body, it's very frustrating," says the country star, 28, who hosted "An Evening with Leann Rimes to Benefit Tornado Relief" (raising $30,000) alongside new husband Eddie Cibrian
, 37, in Florida on Sunday. "I work out and take care of myself, and not in an over-obsessive way."
"People are calling me bulimic or anorexic," she says, "and these are real issues and diseases – that I don't have."
Adds her trainer, Michael Jackson at Equinox in Woodland Hills, Calif.: "My main concern with her is that she's toned and healthy. And she is."
For more on Rimes's diet, workout and health, check out the new issue of PEOPLE, on stands Friday