A survey of 470 female undergraduates claims two thirds reacted "favourably" to adverts using thinner female models.
University of Bath researchers found those preferring thinner models thought diet or exercise controlled weight and were "more likely" to like the product.
Those who believed weight was not controllable tended to be "larger" and less likely to be impressed by a thin model and the advertised product.
It follows calls for a ban on "stick thin" models at London Fashion Week.
The survey also suggested thin models were "more elegant, interesting and pleasant"
Professor Brett Martin, from the university's marketing group in the School of Management, said: "This study shows us why using thin models is a successful strategy used by advertising companies."
The survey's results come after the organisers of last week's Madrid Fashion Week imposed regulations banning "super-skinny" models from the catwalks.
At the weekend, Culture Secretary Tessa Jowell "applauded" the decision, and urged the organisers of this week's London Fashion Week to do the same.
But Prof Martin said the study suggested that the idea that women would respond better to models of "average" build was wrong.
[Thinner women models] "..tend to be more likeable and pleasant too - an idealised version of themselves.
"Women who don't feel weight is under the control of individuals feel the model has just got lucky genetics and are less inclined to see the model as possessing more attractive psychological qualities, though they don't favour larger models either.
"So the recent idea among some commentators that women will respond to models who are average size is generally not right," he said.