We all know that eating too much leads to obesity and that a healthy diet can go a long way toward turning the tide. But does "healthy eating" really always equal healthy results? A new study suggests half the battle may be psychological. Scientists at the Cornell Food and Brand Lab say there is evidence that when people eat what they consider to be healthy food, they eat more than the recommended serving size because they associate "healthy" with less filling.
Published in the Journal of the Association for Consumer Research, the team employed a multi-method approach to see whether the notion is true that food regarded as healthy really does leave us feeling less than full. Their first study looked at 50 undergraduate students at a large public university using what researchers call the "Implicit Association Test." This technique, developed by psychologists, attempts to discover the unconscious bias — the hidden beliefs and prejudices — a participant may have about people and things in their environment.
The second study was of 40 graduate students and measured participants' reported hunger levels after they had eaten a cookie that was said to be either healthy or unhealthy to test the effect of preconceptions on levels of hunger. The third study took 72 undergraduate students and placed them in a realistic scenario — watching a short film. Researchers measured the effect of the perceived healthiness of food on the amount of it ordered before watching the film and the actual amount consumed during the film.
The researchers showed that portraying food as healthy by using a clearly visible nutritional scale on the packaging impacts consumer judgment and behavior. When food was seen as healthy, rather than unhealthy, participants ordered larger portions, consumed greater amounts and reported lower levels of hunger after they'd finished eating. Significantly, even those participants who said they disagreed with the idea that healthy foods are less filling were subject to the same biases.
However, the researchers also found they could reverse the overeating of food portrayed as healthy by highlighting its nutritional aspects. The researchers say their findings add to the understanding of the psychological causes of weight-gain and obesity and point to a way of overturning the assumption that healthy food is somehow less filling. The findings, they say, conclude that, ironically, healthy food labels may actually be contributing to society's obesity problem rather than fighting it and that this knowledge can help consumers take a levelheaded approach to their diet in the future.