The Dieter's Paradox – When more seems less

Imagine Karl, indulging in a juicy meal containing lots of fat and carbs. It’s very yummy but he knows it’s not the healthiest food so he adds a fruit salad on the side, thinking that it will make the meal more healthy and less calorie filled. You reading this might think that Karl is being quite irrational. “When did adding more mean less calories?” But you (and I) are probably not as rational ourselves when it comes down to it... 

In a study by researcher Chernev (2011), people were asked to estimate the number of calories in different meals. The first food options were high-calorie meals such as a hamburger or cheesesteak sandwich. The second option were the same meals but with a healthy meal on the side, for example a salad or celery sticks. Rationally, one would expect that adding another item to a meal would increase the calories. However, that's not what the data showed. On average the respondents thought the unhealthy meal alone to average 691 calories and the meal that also had a healthy item would contain 648 calories. Thus, adding a healthy item decreased the estimated calorie content of the entire meal by an average of 43 calories. This bias (called "The Dieter's paradox") was observed in all four meals tested.

More interestingly? People most concerned with managing their weight were most likely to underestimate the calorie content of meals containing both healthy and unhealthy items. 

This study might be written off as an interesting and fun little insight but since the Dieter’s Paradox shows that people tend to pay attention to what we eat but not how much, this could have negative implications to everyone who has a weight-loss goal. Thus, public policy should not only encourage consumers to manage their weight but also raise awareness about the importance of monitoring the overall quantity consumed.

Adding a salad to our hamburger is great (it adds healthy nutrients to the meal), but it doesn’t miraculously remove calories from the meal. Food for thought…


Chernev, A. (2011). The Dieter’s Paradox. Journal of Consumer Psychology, 21, 178–183. doi:10.1016/j.jcps.2010.08.002