While people have a good sense
of the calories contained in smaller portions
of fast food, they sharply underestimate the
calories in "super size" servings, research
hints.
In the study, people who chose a smaller-size
fast food meal guessed it contained 419 calories,
on average, which was not far off the mark,
given that the actual calorie content was 514.
However, people who picked a larger serving
estimated its calorie content at 675 calories,
when in reality the calorie count was 1,188.
Almost everyone underestimates the amount
of calories they consume, and people who weigh
more do so to a greater degree, but it's not
clear why, Dr. Brian Wansink of Cornell University
in Ithaca, New York and Pierre Chandon of
the graduate business school INSEAD in Fontainebleau,
France note in a report released this week.
The researchers hypothesized that the difference
might occur because it's easier to estimate
calorie content of smaller meals, while heavier
people will choose larger meals and thus have
more trouble gauging how many calories these
meals contain.
To investigate, they performed two experiments.
In the first, they asked 105 people eating
in a fast food restaurant to estimate the
amount of calories contained in the meal they
had just eaten. In the second, 40 students
were asked to gauge the calorie content of
15 different portion sizes of a meal of chicken
nuggets, French fries and cola.
Study participants gauged calorie content
of smaller meals much more accurately, with
guesses within 3 percent of the actual calorie
content. In contrast, they underestimated
larger meals' calorie content by 38 percent
in the first part of the study, and by about
23 percent in the second.
The findings disprove the idea that overweight
people underestimate the amount of calories
they eat because they are in denial or want
to hide their eating habits from others, Wansink
and Chandon conclude. Instead, both normal-
and overweight people misperceive calories
contained in larger portions, and heavier
people are more likely to choose big portions.
"Exhorting good-faith overweight persons
to pay more attention to their meals or to
stop lying to themselves and to their physicians
is unfounded and probably is counterproductive,"
they write.
A better approach, they conclude, would be
to help people find more effective ways to
gauge the calorie content of larger portion
sizes.
SOURCE: Annals of Internal Medicine, September
5, 2006.
