Going for food labeled 'healthy'? Think again

Trying to watch what you eat? Do you reach for the foods labeled “healthy” rather than treats marked “indulgent” in order to cut down?

Not so fast.

New research by a professor of marketing in the W. P. Carey School of Business at Arizona State University found that study participants ate more potato chips after drinking a shake labeled “healthy living” than people who drank one marked “indulgent.”

The results surprised the professor, Naomi Mandel, who was originally trying to see whether a high-sugar shake would prompt more snacking.

“I got into this for personal interest. I’m a sugar avoider. I haven’t eaten sugar in 10 years,” she said, because eating sugary foods makes her hungry.

“There’s not a lot of research and some of it is conflicting, but some nutrition experts say that if people satisfy their craving for sugar, they’ll eat less later. Whereas I propose the opposite.”

The study results found that it depends on whether people think the food is healthy.

Mandel and her co-author in the study, Daniel Brannon of the University of Northern Colorado, who was a doctoral student at ASU at the time, first concocted two kinds of chocolate protein shakes — one that was high in sugar and low in fat and one made with heavy cream and stevia that was low in sugar and high in fat. Both types had the same calorie and protein content. Then they ran a test to make sure people perceived the two to be similar-tasting.

They then ran another pre-test asking 237 people to rate how healthful they believed protein shakes to be. Very healthful, it turns out — 5.2 on scale of 1 to 7, with 7 being "very much so."

Naomi Mandel

The first study involved 76 people, randomly assigned to drink one of the two types of shakes. After drinking the shake, they were asked to do a task that took about 20 minutes, and then they watched a video while eating as many potato chips as they wanted. The subjects believed they were going to rate how well the chips went with the video, but actually, the volume of chips they ate was measured.

Subjects who drank the high-sugar shake did consume more potato chips than the low-sugar group.

The next study is where it got really interesting. The team kept the two kinds of shakes, but some were labeled “healthy living,” with nutrition information showing they were low in fat, sugar and calories, and others were labeled “indulgent,” showing they were high in fat, sugar and calories.

The 193 subjects went through the same procedure: drinking the shake, doing a time-consuming task and then watching a video while eating potato chips.

People who drank a high-sugar shake labeled “indulgent” ate the least amount of potato chips. Those who drank a high-sugar shake labeled “healthy” ate the most. 

“That’s the part that’s a little bit of a puzzle — at some level they seemed to know that it had more sugar and to compensate for that,” said Mandel, who studies issues of overconsumption. The protein shake study is published in the research journal Appetite.

A few years ago, Mandel worked with a doctoral student and other ASU researchers on a study that found that chronic dieters ate more from 100-calorie snack packs.

“We got some attention from that, and we started attracting more PhD students who applied to come here to do these food studies,” she said.

She has two other studies under review — one that investigates messaging around genetically modified foods and another that looks at different types of dieters.

“Although nobody likes the term ‘dieter’ anymore. It’s all about ‘clean eating.’ ”