Could we better gauge how much we eat if we counted calories?  Maybe not.  Our experience with thousands of people suggests that most of us are terrible at estimating how many calories we have eaten so far today, or yesterday, or last week. On average, we generally think we have eaten 20% less than we actually do.[i]  Those three pieces of pizza you thought were 1000 calories were actually 1200, and that 200-calorie donut was actually 240.  But the real concern is with overweight people.  They typically underestimate how much they eat by 40%. They think they eat about half as much as they really do.

This has been a mystery.  Scientists, physicians, and counselors have often blamed overweight people as trying to fool others (or themselves) about how much they are eating. Consequently, some dieticians, physicians, and family members blame and even berate overweight people as “lying” or “being in denial” as to how much they really ate.  Hurtful accusations like these only make diet counseling effective at scaring overweight people off rather than changing them.[ii]

Over the years we have had some overweight people in the Food and Brand Lab. Counter to what the experts say, these people always seemed to be pretty accurate at estimating the calorie content of all sorts of different foods.   They were certainly no less accurate than the skinniest people in the lab.  This was just the opposite of what all the classic scientific studies report.  Why?

To better understand this, we teamed up with a clever French researcher and good friend, Pierre Chandon.  Together we discovered an important key to this mystery in research in an area called psychophysics. It seems that when estimating almost anything – such as weight, height, brightness, loudness, sweetness, and so on – we consistently underestimate things as they get larger.  For instance, we will be fairly accurate at estimating the weight of a 2 lb. rock but will grossly underestimate the weight of an 80 lb. rock. We will be fairly accurate in estimating the height of a 20 foot building but will grossly underestimate the height of a 200 foot building. Chandon believes this is the key to the calorie mystery.  At high levels all of us – normal weight and overweight alike – underestimate calorie levels with mathematical predictability.[iii]

The secret to this mystery may not in the size of the people, but in the size of the meal.[iv]  The bigger the meal, the less accurate we all are at estimating how many calories it has. To test this idea, we started in the lab and moved to a food court.

First, we recruited 150 people who were either normal weight or obese.  We then bought a dozen different meals of all different types – small sandwiches, huge sandwiches with chips, small chicken dinners, large chicken dinners with fries and a 32 ounce Coke, and so on.  We asked each person to estimate the number of calories in each of the 12 meals.  The results were alike, regardless of a person’s weight.  The smaller the meal, the more accurate people are at estimating its calorie-level.  The larger and larger the meal, the fewer and fewer calories they thought it contained. Everyone estimated huge 2000 calorie meals as only having 1200 calories or so. There were no differences in the estimates of the skinniest people or of the largest people.

If normal weight and overweight people are equally biased in their estimates of calories, why is it that overweight people are almost always off by 40%?

We ran a second study in a number of food courts to find out why.  In these food courts, we asked 200 people randomly selected people what they had for lunch and how many calories they thought they ate (and drank).  The more people had eaten, the less accurate they were.  Someone eating a small, 300 calorie hamburger and a salad would underestimate the calories by about 10%, but someone eating a 900 calorie Monsterburger would underestimate it by a whopping 40%. It did not matter whether the person was skinny or huge, male or female, the bigger the meal, the less they thought they ate.

It is “meal size,” not “people size” that determines how accurate we will be at estimating how many calories we have eaten. That popsicle-stick skinny person eating a 2000 calorie Thanksgiving dinner will underestimate how much they have eaten by just as much as the heavy person eating a 2000 calorie pizza dinner. The trouble is that the heavy person tends to eat a whole lot more of these big meals. 

It's meal-size, not people-size.

​References
​
[i]This gap in our calorie estimation and the exaggerated gap among obese peole has been widely reported by top scholars over the past 20 years.  The classic studies include: David Lansky and Kelly D. Brownell, "Estimates of food quantity and calories: errors in self-report among obese patients," American Journal of Clinical Nutrition (1982), 35:4, 727-32.  Steven W. Lichtman, Krystyna Pisarska, Ellen R. Berman, Michele Pestone, H. Dowling, E. Offenbacher, H. Weisel, S. Heshka, D.E. Matthews, S.B. Heymsfield, "Discrepancy Between Self-reported and Actual Caloric Intake and Exercise in Obese Subjects," New England Journal of Medicine (1992), 327:27, 1893-1898.  M. Barbara E. Livingstone and Alison E. Black, "Markers of the Validity of Reported Energy Intake," Journal of Nutrition (2003), 133:3, 895S-920S.  Janet A. Tooze, Amy F. Subar, Frances E. Thompson, Richard Troiano, Arthur Schatzkin, and Victor Kipnis, "Psychosocial Predictors of Energy Underreporting in a Large Doubly Labeled Water Study," The American Journal of Clinical Nutrition (2004),79:5, 795-804. 

[ii]Shirley S. Wang, Kelly Brownell, and Thomas Wadden, “The Influence of the Stigma of Obesity on Overweight Individuals,” International Journal of Obesity (October 2004), 28:10,  1333-1337. 

[iii]  This is mathematically predicted by a compressive power function.  The math is so painful, it even makes me weary. Anyway, the details (including the math) can be found in the very dense and very cool following article in one of the top journals in this field: Pierre Chandon and Brian Wansink, “Obesity and the Calorie Underestimation Bias: A Psychophysical Model of Fast-food Meal Size Estimation,” Journal of Marketing Research, (2006). 

     No one goes to bed skinny and wakes up fat. Most people gain (or lose) weight so gradually they cannot really figure out how it happened.  They do not remember changing their eating or exercise patterns.[i]  All they remember is once being able to fit into their favorite pants without having to hold their breathe and hope they can get the zipper to budge. 

       Sure, there are exceptions.  If we gorge ourselves at the all-you-can-eat pizza buffet, then clean out the chip bowl at the Superbowl party, then stop by the Baskin-Robbins drive-through for a “Belly Buster” Sundae on the way home, we realize we have gone too far over the top.  But on most days we have very little idea whether we have eaten 50 calories too much or 50 calories too little.  In fact, most of us would not know if we ate 200 or 300 calories more or less than the day before.

          This is the Mindless Margin.  It is the margin or the zone in which we can either slightly overeat or slightly undereat without being aware of it.  Suppose you can eat 2000 calories a day without either gaining or losing weight.[ii]  If one day, however, you only ate 1000 calories, you would know it.  You would feel weak, light-headed, cranky, and you would snap at the dog.  On the other hand you would also know it if you ate 3000 calories.  You would feel a little heavier, slower, and more like flopping on the couch and petting the cat.

          If we eat way too little, we know it.  If we eat way too much, we know it.  But there is a calorie range – a Mindless Margin– where we feel fine and are unaware of small differences.  That is, the difference between 1900 calories and 2000 calories is one we cannot detect, nor can we detect the difference between 2000 and 2100 calories.  But over the course of a year, this mindless margin would either cause us to lose ten pounds or to gain ten pounds.  It takes 3500 extra calories to equal one pound. It does not matter if we eat these extra 3500 calories in one week or gradually over the entire year.  They will all add up to one pound.  

            This is the danger of creeping calories.  Just 10 extra calories a day – 1 stick of Doublemint gum or 3 small Jelly Belly jelly beans – will make you a pound more portly one year from today.[iii]  Only three Jelly Bellies a day.
            Fortunately, the same thing happens in the opposite direction.  

One colleague of mine, Stacy, had lost around 25 pounds during her first two years at a new job.  When I asked how she lost the weight, she could not really answer.  After some persistent questioning, it seemed that the only deliberate change she had made two years earlier was to give up caffeine.  She switched from coffee to herbal tea.  That did not seem to explain anything.

            “Oh, yeah,” she said, “And because I gave up caffeine, I also stopped drinking Coke.”  She had been drinking about six cans a week – far from a serious habit – but the 139 calories in each Coke translated into 14 pounds a year.  When she quit, she was not even aware of why she had lost weight.  In her mind all she had done was cut out caffeine.

            Herein lies the secret of the Mindless Margin.  This Mindless Marginis that small range where we make slight changes to our routine that we hardly notice.  Nevertheless, these changes can have a gradual – but eventually big – impact on our weight. They can make the difference between being 10 pounds heavier next New Years Day or 10 pounds lighter. 

     Cutting out our favorite foods is a bad idea. Cutting down on how muchwe eat is mindlessly doable.  Many fad diets focus more on the typesof foods we can eat rather than how much  we should eat.  The problem is not that we order beef instead of a low-fat chicken breast. The problem is that the beef is often twice the size. A low-fat chicken breast that we resent having to eat is no better for our long-term diet than a tastier but slightly smaller piece of beef.
​
         If we are looking at only a 100 or 200 calories difference a day, these are not calories we will miss.  We can trim them out of our day relatively easy – and unknowingly.   The key is to do it unknowingly – mindlessly.  

       We sometimes hear that a child “inherited” their sweet tooth, or their love for vegetables, or for spicy foods from a parent. Although the genetics jury is still out, it is clear that children adopt some of their mother’s tastes when they are still snoozing away in the womb.   For instance, pregnant women who drank carrot juice in their last trimester significantly increased how much their children preferred carrot-flavored cereal months later.[i]

Not only do they develop prenatal munchie preferences, children also start learning what they like and don’tlike before they are four months old.  They do this by picking up on signals a parent or caretaker unconsciously gives about whether a food is tasty or not.  

This was first discovered in the Massachusetts Reformatory for Women during the 1940s.  The women incarcerated here were able to keep children under 3 years of age and to frequently visit them and their carekeepers in the nursery. Records were kept on what the children ate, so it became suspicious when all of a sudden their juice preferences abruptly changed.  The psychologist at the reformatory, Sibylle Escalona, began to suspect that the caretakers were unconsciously influencing what the children preferred.[ii]

Her report starts out, “It came to attention accidentally that many of the babies under four months of age showed a consistent dislike for either orange or tomato juice.”  She then went on to report that babies who had refused to drink orange juice for about three weeks would all of a sudden turn into orange juice lovers within two or three days.  She traced these abrupt changes to changes in caretakers.  Upon being interviewed, it was found that a couple of the new carekeepers had a strong preference for orange juice and a dislike for tomato juice. Somehow this was passed along to the four month infants.

But how?  Interestingly, even two-day-old babies are thought to be able to imitate facial expressions of adults.[iii]  It could be that these caretakers subconsciously showed subtle signs of acceptance or rejection based upon what they personally felt toward the foods.  A fleeting smile or grimace might go a long way toward explaining why one baby has daddy’s sweet tooth and another has mommy’s love for vegetables.  This also makes good sense that people feeding babies pretend to taste the food (Mmmm . . . yummy!”) and to open their mouths and play “airplane hanger” when feeding the little tykes.[iv]

Escalona’s accidental discovery has aged well. Watching someone smile or grimace when eating food scares elementary children away from even an otherwise tasty food.[v]  And this also works with being friendly – you can attract more children to new foods with honey than with vinegar.  When a friendly adult repeatedly gave children either canned unsweetened pineapple or cashews, they quickly learned to like this food more than when it was given to them by a less friendly adult.[vi]

It is not only our tastes that our children can inherit.  It can also be our attitudes about food and eating.  In one Yale study of normal weight one-year olds, mothers who were highly preoccupied with weight issues were more likely to be erratic in their behavior during meals.  Sometimes, they urged their one-year-olds to eat more, sometimes to eat less, and sometimes they rushed their feedings.  They were also much more emotionally aroused when feeding their babies compared to mothers who were not concerned with weight issues.[vii]  Children see this anxiety and these food obsessions at a tender tabla rosa age. 

Just as our children can inherit our eye color and hair color, they might also be behaviorally imprinted with our obsessions with food or with weight.  Fortunately, when they start to talk we can even more quickly imprint a passion for balanced meals, smaller portions, vegetables, and fruits.[viii]

​References
[i]A good example of the power of availability is Marsha D. Hearn, Tom Baranowski, Janice Baranowski, Colleen Doyle, Matthew Smith, Lillian S. Lin, and Ken Resnicow, “Environmental Influences on Dietary Behavior Among Children:  Availability and Accessibility of Fruits and Vegetables Enable Consumption,” Journal of Health Education(1998), vol. 29, pp. 26-32.

[i]See Julie A. Mennella and Gary K. Beauchamp, “The Early Development of Human Flavor Preferences,” in Why We Eat What We Eat:  The Psychology of Eating, ed. Elizabeth D. Capaldi, Washinton, DC: American Psychological Association, 1996.

[ii]This is a classic:  Sibylle K. Escalona, “Feeding Disturbances in Very Young Children,” American Journal of Orthopsychiatry(1945) 15:76-80.

[iii]T.M. Field, R. Woodson, R. Greenberg, and D. Cohen, “Discrimination and Imitation of Facial Experssions by Neonates,” Science, (1982) 218:179-181. 

[iv]Thanks to Alexandra Logue for this example from her incredible book, The Psychology of Eating and Drinking, 3rdEdition, (New York: Brunner-Routledge, 2005).

[v]F. Baeyens, D. Vansteenwegen, J. De Houwer, and G. Crombex, “Observational Conditioning of Food Valence in Humans,” Appetite,(1996) 27:235-250.

[vi]Much of the most interesting research in this area is by LeAnn L. Birch.  See, “Generalization of a Modified Food Preference,”  Child Development, (1981), 52:755-758.

[vii] Pike and Rodin , "Mothers, Daughters and Disordered Eating", Journal of Abnormal Psychology, 1981.

[vii] B Wansink,  Mindless Eating: Why we eat more than we think,  p. 168-171.  

[xi]  Excerpted from the American Dietetic Association’s excellent book, Dieting for Dummies (Wiley, 2004).