However, an independent expert has found the study by Johnson and Johnson was flawed because it lacked objective measures, records and corroborating photography.
"We concluded the ad was misleading," the Independent quoted the ASA, as saying.
The watchdog has banned the advert and warned the US medical, pharmaceuticals and consumer giant to consult the Committee of Advertising Practice before advertising again.
Johnson & Johnson had claimed that women who used RoC CompleteLift would experience a "measurable lift".
A patented ingredient in the product called THPE was "clinically proven to work in just 8 weeks of use," the advert said. A footnote explained: "Clinical study, 41 women, 8 weeks of use."
Members of the public complained after noticing another statement in the small print that the product did not give a "physical lift".
The cosmetic giant said in its defence that its research showed the product gave a "measurable lift" as long as people used it - rather than a permanent lift.