The Dieter’s Paradox: When More Feels Like Less (Psychology / Food)

Why we pay attention to what we are eating, but not how much.

He thought, “this has a lot of calories, I really shouldn’t eat it.” It was a rich, creamy serving of ice-cream and he was already pretty full.

So he added some chopped nuts and strawberries. Somehow convinced that it now had fewer calories, and guilt free, he dug in.

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Only a twisted mind would think you can decrease calories by adding more. So I guess I have a twisted mind, because “he” is me. I laugh about it, but my attitude has a lot to do with the epidemic of obesity in this country.

Is it only twisted minds that do this, though? Or do we all do it? Let’s look at some data.

Chernev (2011) asked people to estimate the number of calories in various meals, including a cheesesteak condition (yum).

There were two conditions:

• Unhealthy alone — for example a cheesesteak sandwich.
• Unhealthy plus healthy — for example the same cheesesteak sandwich plus a side of healthy vegetables.

Calorie ratings were higher for the unhealthy meal alone. Adding the healthy side made the meal seem to have fewer calories. In other words, x + 1 is less than x. Chernev (2011) called it the dieter’s paradox.

There was more. Weight conscious individuals were especially likely to show this effect. They thought the carrots and celery decreased calories by a lot, which is surprising if you assume they’d be most tuned in about estimating calories.

This study, and my ice-cream consumption, is an example of scope neglect. When we make judgments we aren’t very good at paying to attention to how big something is. Another example is that people will pay about the same amount to save 2,000 birds as to save 200,000 (Desvouges et al., 1993).

The dieter’s paradox is fundamental to the obesity epidemic in America. We pay attention to what we eat but not how much. When we look at the French, with their rich food, we wonder why they aren’t overweight. When we look at ourselves, with our huge servings that (sometimes) aren’t as calorie-dense, we wonder why we are overweight. That’s like wondering why ice cream alone has fewer calories than ice-cream with nuts and fruit on it.

References: (1) Chernev, A. (2011). The Dieter’s Paradox. Journal of Consumer Psychology, 21, 178–183. doi:10.1016/j.jcps.2010.08.002 (2) Desvouges, W.H., Johnson, F., Dunford, R., Hudson, S., Wilson, K., and Boyle, K. 1993. Measuring resource damages with contingent valuation: Tests of validity and reliability, in: Contingent Valuation: A Critical Assessment. Amsterdam: North Holland.