Research conducted at Simon Fraser University suggests the inclusion of plus-size models in advertising results in less motivation to have a healthy lifestyle, but critics say the results are overly-simplistic.

The study, The (Ironic) Dove Effect, claims one of the reasons why being larger-bodied appears to be "contagious" when seen in advertising is because it's seen as more socially permissible, especially when it's coupled with certain types of messaging.

The research suggests after having seen plus-size models along with those types of statements, the study's subjects made poor food choices, had lower intentions to exercise, and had lower support for programs that serve to curb obesity.

SFU assistant professor Brent McFerran says it's probably best to use a variety of body types in advertising and not make judgement calls on their sizes. (CBC)

"There's some downside to using larger models and then coupling that with statements like, 'these people are real' or normal,' making some value judgements saying that it's ok to be overweight or obese," says study co-author Brent McFerran, assistant professor of marketing at SFU's Beedie School of Business.

McFerran said research has shown that under-sized models in advertising also have negative effects, as has using larger models and "fat-shaming" them.

"Swinging the pendulum too far in either direction ... is probably problematic," said McFerran.

"The usage of a range of body types is probably a good thing, so long as we're not holding up either one of those bodies, be it large or be it small, and saying this is what you should strive to, or this is good."

Study 'overly simplistic'

Plus-size model Ruby Roxx decried the research, saying it's "overly simplistic."

Plus-size model Ruby Roxx says the latest research out of SFU is overly-simplistic. (CBC)

"I don't watch these ad campaigns and go, 'There's my excuse not to go to the gym that day,'" she said. "It doesn't work that way."

She says regardless of the results, a person's size has nothing to do with how healthy they may or may not be.

"Only a doctor can tell you that," she said.

"You just need to think, the weight I'm at: Am I healthy? Am I happy? If I'm not, what can I do to change that? It's not about being something unrealistic."

The models used in the research were women who met the medical requirements for obesity, meaning they had a BMI of over 30. The series of five studies included in the research had about 800 subjects all together. The research was published in the Journal of Public Policy & Marketing.