Katharine McPhee used to have "a lot of issues" with food

She told this week's edition of UsWeekly: "The problem is [when] you're having, like, three milkshakes instead of one. So I've been into intuitive eating for a long time.

"I had a lot of issues around food. And the more pressure that I had put on myself, like, 'Oh, my God, it's the holidays. Don't go crazy. You can't eat this,' the more crazy that I went."

The singer - who first found fame on 'American Idol' in 2006 and later starred in the NBC musical drama series 'Smash' - no longer feels the "pressure" she once did when it comes to her diet.

She said: "You can indulge a little bit, but it's no different than indulging on Valentine's Day and indulging on the Fourth of July.

"I don't feel pressure on myself, just the more pressure you put on a certain time, the more you're likely to overindulge. So that is the principle I live by - not setting such rigid rules for myself."

Katharine is a "big believer" in gut health, and is thrilled to have discovered Bio.me's new Daily Prebiotic Fiber.

She said:"I'm a big believer in that the gut is essential to great, strong immunity. I've always been into probiotics and yoghurts.

"We all know fibre is important. I'm thrilled to have another thing to make it easier to just feel good.

"I have a lot of joint issues, even for only being 40, I have a lot of aches and pains from years of dancing. So all that kind of [fiber] stuff is a [godsend]."