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Think about health when faced with tough decisions

Posted Aug 18 2011 12:50pm

Planning in advance to eat healthfully is quite easy – but what happens when you are confronted with an immediate decision between healthy and unhealthy food – especially when you are hungry?

Here’s an example: you’re at a party where everyone is munching on chips, cheesy dips, and greasy finger foods. You see a platter of raw vegetables and fresh fruit, but you feel tempted by the junk food. Do you stick with the produce or indulge in the calorie-laden snacks?  What goes on in your brain while you’re making that decision?

Subconsciously, we assign a certain value to each food, asking ourselves, “How will each of these foods taste? How healthy is each one? What is more important to me right now, taste or healthfulness?”

Vegetable platter. Flickr: Bruce Guenter


Junk food. Flickr: bloomsburys

Decision-making is thought to be controlled by part of the brain called the ventromedial prefrontalcortex (vmPFC), which also plays a role in regulating emotions and emotional reactions.  A 2009 study found that another region, the dorsolateral prefrontal cortex (dlPFC), may help the vmPFC to decide that healthfulness is more important when making food decisions.   In people who showed more self-control in their food choices, the vmPFC was activated by pictures of foods they had as healthy and foods they rated as tasty; however, in people with less self-control, the vmPFC was only activated by foods they rated as tasty, not the ones they rated as healthy. Also, those with more self-control had more activity in the dlPFC during food decisions.  These results suggest that the dlPFC may reduce the value that the vmPFC assigns to tempting unhealthy foods, helping us to exert self-control in our food decisions.1

So, can we choose to activate the dlPFC to have more self-control when making food decisions?  If so, how? 

That’s exactly the question that this research group’s newest study tried to answer. Subjects were asked to fast for at least three hours prior to the experiment. They were shown pictures of 180 different foods and asked to respond within three seconds “yes” or “no” to whether they’d want to eat the food.  Before they experiment, they were told that one of their choices would be randomly selected, and if they answered “yes” for that food, it would be served to them later. 

Before each group of 10 food photos, a message would be displayed on the screen saying either "consider the healthiness," "consider the tastiness," or "make decisions naturally." These messages were designed to shift the subjects’ attention toward either taste or health – if they were reminded to think about health, would it change their brain activity and cause them to make a healthier choice?

The answer was yes. After seeing the “consider the healthiness” message, subjects were less likely to choose unhealthy foods, and more likely to choose healthy-untasty foods.  They also said “no” to foods more often after seeing the “healthiness” message than after seeing the “naturally” message.  

What was going on in the brain? In response to pictures of healthy foods, the vmPFC showed more activity in the presence of the “healthiness” message compared to the other messages.  The dlPFC was more active in response to all of the food pictures in the presence of the “healthiness” message compared to the other messages.  This result suggests that the dlPFC was more able to help the vmPFC put more value on healthiness after the “healthiness” message.   The subjects made healthier choices when they were reminded to do so.2,3

The message here is that making the tough decisions between taste and health is easier than we think – if we can remind ourselves that health is the more important quality, we can alter the way the brain values the foods involved.  When faced with a decision between delicious healthy food and tempting unhealthy food, we can use reminders to shift our attention toward health:

According to this research, reminders like these do work.  We can train ourselves (and our dlPFCs) to use healthfulness as the most important quality by which we value foods.

*GOMBS  = Greens, Onions, Mushrooms, Beans, Berries, Seeds

 

References:

1. Hare TA, Camerer CF, Rangel A: Self-control in decision-making involves modulation of the vmPFC valuation system. Science 2009;324:646-648.

2. Think healthy, eat healthy: Caltech scientists show link between attention and self-control. EurekAlert! http://www.eurekalert.org/pub_releases/2011-07/ciot-the072611.php . Accessed August 15, 2011.

3. Hare TA, Malmaud J, Rangel A: Focusing Attention on the Health Aspects of Foods Changes Value Signals in vmPFC and Improves Dietary Choice. J Neurosci 2011;31:11077-11087.


 

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