Overweight And Thin People Might Actually See Food Differently

It isn't an inability to understand nutrition.

16/04/2016 7:55 AM AEST | Updated 16/04/2016 7:58 AM AEST
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When presented with hypothetical food choices, overweight and lean people made similar choices. When presented with those same foods in real life, overweight people were more likely to consume unhealthy options. 

Educating people about healthy eating is a nice idea, but does it result in healthier habits? Not necessarily, according to researchers at the University of Cambridge who published a study on the subject in this month's issue of eNeuro.

Their study of lean and overweight people concluded that education wasn't the problem when it comes to poor dietary choices. When presented with hypothetical food choices, both groups made similar choices about which foods they preferred -- indicating a common understanding about what constituted a healthful food. But when the study's participants were presented with those same foods at a real-life buffet, the overweight group was more likely to consume the unhealthy options. 

"One possibility is that there are powerful (perhaps subconscious)
stimulus effects of the real foods," study author Nenad Medic, a researcher in the psychiatry department at Cambridge, told The Huffington Post via email.

In other words, the way overweight people experience available food may override their ability to stick to the healthy choices they'd planned before being presented with food, Medic explained. "Among the overweight people, those who were more impulsive were vulnerable to the attractive effects of the unhealthy foods."

The difference between overweight and lean people might not be limited to conscious decision-making: A companion study, published in the International Journal of Obesity in March, used fMRI technology to find that the brain area responsible for processing value judgements was thinner in overweight and obese people than it was in lean people.

The underlying message is that environmental factors might play a bigger role in obesity than researchers previously realized. Without overhauling the environmental triggers that lead to unhealthy eating, health education probably isn't enough to change people's behavior. 

Brain differences don't fully explain what causes obesity

While the eNeuro study was relatively small -- just 23 lean and 40 overweight study participants -- the researchers adjusted for age, gender, income, education and IQ. But although they noticed demographic differences between study participants with high and low educational attainment and between high and low earners, the study wasn't sufficiently powered to examine those differences in a meaningful way. 

"We have not directly examined the contribution of inequality or poverty on value judgements or eating behavior," Medic said. "Our findings do, however, suggest that the food environments, or the availability of foods, may promote unhealthy food consumption, despite people’s intentions to eat healthily."

To be clear, the study didn't find a connection between eating unhealthy foods and inequality. But previous research suggests that food availability affects eating patterns. According to a study published in the Journal of the American Osteopathic Association in September, food insecure children have the greatest risk for developing obesity. Among adolescents, those with "marginally low,” “low,” and “very low” food security were 33 to 44 percent more likely to be overweight and 1.5 times more likely to be obese than those who had sufficient access to enough food. And according to the Centers for Disease Control and Prevention, obese children are more likely to become obese adults.

Hunger and obesity are often flip sides to the same malnutrition coin,” Joel Berg, executive director of the New York City Coalition Against Hunger, told the New York Times in 2010. “Hunger is certainly almost an exclusive symptom of poverty. And extra obesity is one of the symptoms of poverty.”

The new study should serve as a warning about the efficacy of information-only public health campaigns -- such as calorie counts on menus -- that focus solely on educating people about the healthiness of food.

"It seems that this is not enough, given that the food environment -- the presence of unhealthy foods -- is likely to override people’s judgements," Medic said.

On the other hand, the new study could serve as fodder for pro-taxation advocates, who argue that taxing unhealthy foods, such as soda, could encourage consumers to eat or drink less of it. 

According to a study published in the British Medical Journal in January, soda sales in Mexico fell across all socioeconomic groups after the country enacted a beverage tax in 2012. That drop-off was highest among low-income households, who averaged a 9 percent decline in soda purchases during 2014, and a 17 percent decline in soda purchases by the end of 2014, compared to their pretax purchasing habits.

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