Demi Lovato had to give up her raw food, gluten-free diet at a recent house party because she did not want to offend host Robert Rodriguez or special guest President Barack Obama.

The singer is obsessed with healthy eating after learning she has allergies to gluten and dairy, but she had to dine and dare at moviemaker Rodriguez's home in Austin, Texas last month (Jun14), when she realised he was making pizza for everyone.

She tells Extra, "I try to eat raw food whenever possible. I don’t eat it all the time just because I’m the type of person that if I do something, if I go all one way, I get burnt out... I’m gluten-free and dairy-free because I’m allergic to them. I just eat vegan and raw as much as possible and it's really changed my body and made me feel better.

"But you kind of can’t turn down pizza that Robert Rodriguez handmade - and that you are also eating with the President."

Rodriguez's star-studded house party served as a fundraiser for the Democratic National Committee. Jessica Alba and Rosario Dawson were also among the guests.