Oprah Winfrey once declined a party invite because she thought she was "too fat".

The 70-year-old TV star embarked on a weight-loss journey in the late 1980s - but Oprah found that in spite of her best efforts, she quickly regained the weight that she had lost.

During an appearance on 'The Jamie Kern Lima Show', Oprah shared: "I didn't have a morsel of food for five solid months in losing that weight on [the all-liquid diet] Optifast.

"Three days later, I was 5 lbs. heavier, and a week later I was 10 lbs. heavier.

"The week before Christmas, I remember Don Johnson - the Don Johnson, of 'Miami Vice' - was having a party and had invited me and some members of my show to come, and I wouldn't go because I thought I was too fat to go."

Oprah recalled feeling a sense of shame about her weight struggles.

She said: "I'd gone from 145 [lbs.] on the day of the show. I think I was 157 [lbs.] in the course of, like, a week and a half or two. And the shame started again."

Despite this, Oprah previously confessed to being a "steadfast participant" in America's diet culture.

The veteran TV star acknowledged that she's played an influential role in shaping the conversation around diet and health in the US.

Oprah - who hosted her own TV talk-show for 25 years - said on a YouTube special earlier this year: "I want to acknowledge that I have been a steadfast participant in this diet culture.

"Through my platforms, through the magazine, through the talk show for 25 years and online, I've been a major contributor to it. I cannot tell you how many weight-loss shows and makeovers I have done and they have been a staple since I've been working in television."