The survey found 8 per cent of women did not apply for a job that they felt they were qualified for because of doubt about their physical appearance.
Kellogg's Australia New Zealand spokeswoman Tamara Howe said the campaign aimed to counter the negativity women directed at their bodies.
"While we may not be able to eliminate self-doubt for women, we can be their ally in the fight against it, by exposing how widespread it is and becoming an advocate for body confidence and inner strength. When Kiwi women are able to take control of self-doubt, they are stronger, more confident and ultimately empowered."
Women's Health Action, a charitable trust aimed at improving body image among young people, is also involved in the campaign.
Director Julie Radford-Poupard said body image was a critical health issue, particularly for women and girls.
"The Special K #OwnIt campaign is a welcome addition to the cause. It highlights the role body image can play in such damaging practices as depression, bullying, eating disorders, reduced physical activity, poorer sexual health, diminished sexual negotiation, risk taking behaviours and lower self-esteem."