Why Are We So Bad at Counting Calories?

Do you know how many calories are in a Big Mac? What about a Subway sandwich? If we could get better at realizing exactly how much we eat, we’d have a better shot at controlling our weight—and our health.

"Mmmmm...donuts." Many Americans aren't very good at estimating how much we actually eat—which has a huge impact on our health. (Getty Images/katesea)

May 27, 2013· 2 MIN READ
Lorie A. Parch is a Los Angeles-based writer specializing in health and lifestyle topics.

The evidence is damning: As calorie counters, Americans pretty much suck. That may be self-evident when you look around at how much millions of us weigh, but research has backed it up. When asked how much we’ve eaten, we reliably underestimate the amount—by a lot.

A new study, just out in the journal BMJ, bolsters previous research and further proves that very often we simply don’t realize how much we’re eating. The new study looked at the calorie content of meals from 89 fast-food restaurants in New England and asked adults, teenagers, and school-age kids to guesstimate how much they were eating.

What did the researchers find? The actual median calorie counts for the adults’ and teens’ meals were 836 calories and 756 calories, respectively. But both underestimated their food by 175 calories. “That may not sound like a lot, but it is because it adds up over time,” says Lisa Young, Ph.D., R.D., a nutritionist in New York City, adjunct professor at New York University, and author of The Portion Teller Plan. “Also, this is not the only thing they are underestimating,” she adds, meaning that those surveyed also are likely to fail to account for extra fat and sodium, for instance.

“At least two-thirds of all participants underestimated the calorie content of their meals,” wrote the study authors, “with about a quarter underestimating the calorie content by at least 500 calories.” Eat 500 extra calories every day for just one week and you’ve added one pound right there.

Think you could do better at guesstimating what you’re eating? Take this short quiz and see how you do (the correct answers are at the bottom):

1. A McDonald’s Big Mac has:

a. 550 calories

b. 730 calories

c. 865 calories

2. A Subway Chicken and Bacon Ranch Melt (6-inch sub):

a. 490 calories

b. 570 calories

c. 780 calories

3. A Burger King Double Whopper has:

a. 200 calories

b. 255 calories

c. 830 calories

4. Two Dunkin’ Donuts chocolate frosted doughnuts have:

a. 300 calories

b. 540 calories

c. 735 calories

5. Three KFC Extra Crispy Tenders have:

a. 380 calories

b. 455 calories

c. 800 calories

How can we better figure out what we’re really putting into our mouths so we can get a handle on our weight and health? Keep it simple: “We underestimate larger portions more, so having a small [size] is a better bet,” says Young, adding that most Americans need more education about why it's important to pay attention to nutrition counts (the fast-food chains in the BMJ study did have nutritional information available, but only 5 percent of adults and 2 percent of teenagers used that information to guide the food they chose). And don’t forget to note foods that can have hidden calories, adds Young: “Sauces, mayo, cheese—many people forget to include these” when totaling up how many calories are in a dish or meal.

Also, be aware of fast-food (and other) restaurants that seem to be healthier, but potentially aren’t. “There is a health halo with places like Subway,” notes Young. “People think they are healthier, so they may underestimate those items even more, as they perceive them as healthy.” The new study showed that diners were more likely to underestimate their calorie counts at Subway than they were at McDonald’s, in fact.


1. a

2. b

3. c

4. b

5. a

How did you do on the quiz? If you keep an eye on what you eat when you eat out, how do you track it?