Research Reviews

Research Review: Lying (food) labels

by Helen Kollias

I’m sure you’ve heard of vanity sizing, in which clothing companies change the clothing labels so it looks like you’re a smaller size. For instance, they might relabel a size 16 as a 12, a medium as a small (thus creating the puzzling categories of sizes 0 and 00, or XS and XXS).

That seems silly to me. When I first figured this out, I couldn’t believe anyone would really care so much about a label.

I was wrong.

I didn’t believe in the power of vanity sizing until I had a roommate who was supposedly a size 0 (yes, go ahead, hate her) and found a perfectly fitting pair of pants with one problem: They were a size 6! She told me the story justifying her rejection of said pants:

“I’m a size 0, not a size 6, so I couldn’t buy the pants.”

What does a size 16, 8, or 0 mean? How can you be a size 0 (or weirder, 00) and still exist? Isn’t that some kind of mathematical paradox?

Even though many labels are arbitrary and have no meaningful reference point, they affect how we see ourselves.

Having clothes that are smaller sizes make us feel skinnier. Can the same thing happen with food labels?

If a food package is labelled as smalI will you eat more of it than the same package labelled as large?

Sounds crazy? Just like vanity sizing.

Guiltless gluttony

Over the years you’ve probably noticed that a large sized portion at your local fast food place has magically become a small and what would’ve been called feeding a small village is now called large.

Could your memory be misleading you? Nope.

Studies have found that from the 1970s to late 1990s French fries, hamburgers and soda portions have more than doubled (1).

Big deal. We’ll just eat half a portion, right?

If we were completely objective or used systematic processing then we’d take a look at the Fred Flintstone-sized container of fries, realize they were bigger, and eaten only until we were satisfied, but that doesn’t happen.

Systematic processing

Systematic processing (2) is what a completely logical and objective person would do (think of Spock or Data from Star Trek).

Basically, you take in all the information:

This medium container holds 750mL.

Then you scrutinize the information:

Yup it looks like it holds 750mL; last time a medium was 500 mL.

And then you make a judgment call:

This container has 50% more than last time. Thus I will only consume 500 mL, because that satisfied me last time.

Logical, but a lot of work. And it’s not really how most humans think. (Even though that’s how we would like to think we think.)

 Research Review: Lying (food) labels
“So, I told them it would be totally illogical to supersize this… I mean, the plate has a 10.16 cm radius already…”

Heuristic-systematic model

Unlike systematic processing, heuristic-systematic model (HSM) processing (3) is impulsive and simple (think of a 2 year old).

In this decision model there is little to no information gathering or processing, no scrutinizing, and no judgement. It is quick and takes less effort.

Some researchers suggest that this makes us less logical but more efficient in evolutionary terms — we don’t have to spend time figuring out all the factors involved. We see teeth and fur, we smell feline funk, we think tiger and run like heck. And we remember the tiger for next time. We don’t need to re-learn that a tiger-shaped object is bad news. Our brain creates a mental shortcut.

In the heuristic-systematic model, you get a medium container and don’t notice it’s bigger than last time. You consume all of it without noticing you consumed 50% more than last time.

Your heuristic-systematic processing system has put the pieces together, called that collection of characteristics medium and archived it. You don’t mentally update that file. A medium is a medium. Mental shortcut.

Although it’s an evolutionary advantage in terms of thinking efficiently, this is a disadvantage in a food world where things are not what they seem. That tiger could be a stuffed animal or a house cat. That medium could be… well, you’ll see.

Research question

This week’s review looks at a series of studies examining guiltless gluttony.

  • How do size labels change how much you think you eat?
  • How much you actually eat?
  • How do distractions make things worse?

Ayinoglu NZ, Krishna A. Guiltless gluttony: The asymmetric effect of size labels on size perceptions and consumption. Journal of Consumer Research, April 2011 Vol 11 ahead of print.


This article covered 5 studies, all of which looked at how food size labels affected people’s decisions.

The studies tested how food labels affected people’s food perception, food intake, and sense of fullness.

Researchers gave different people food (peanuts, cookies, pretzels or mini-sandwiches) with different labels (small, medium or large). All packages were in fact the same size.

  • Some studies showed that labels changed participant’s estimates of size. For example, if a package of nuts was labelled small instead of medium, people tended to underestimate the number of nuts in the package.
  • Other studies showed that labels changed how much food the participants ate and how much they thought they ate. For example, if a package of nuts was labelled as small instead of medium, people ate more, but didn’t realize it.
  • Some studies looked at how distractions or unconscious decisions affected people’s awareness and consumption of mislabelled food consumption and size estimates.

All in all, the series looked at how food size labels affect:

  • how much food you estimate there is;
  • how much food you eat;
  • how full you feel after; and
  • how much attention you give to eating.


Labels affect correct estimation

Two studies found that when mini-pretzels or peanuts were labelled as small (instead of medium) people estimated the packages contained fewer pretzels or peanuts.

In study 1, if an 8-pretzel package was labelled as medium, people guessed there was about 4 pretzels (not a very good guess). If the 8-pretzel package was labelled as small then people guessed that there were 3. Thus, people thought there were about 25% fewer pretezels in a smaller-labelled package.

Labelling a bigger package as smaller causes people to decrease their estimates by 25%, but the opposite (labelling small packages as larger) isn’t true.

Study 2 was similar. Packages of peanuts (60 peanuts) were labelled as medium or small.

When people got 60 peanuts in the medium labelled package they guessed there were 64 peanuts. When they got the same package labelled as small they guessed 52 peanuts — or about 20% fewer peanuts.

Remember the only difference in both these studies is the package label.

jelly bean jar 268x300 Research Review: Lying (food) labels

Labels affect food consumption

Okay, big deal. People thought there were fewer peanuts. Not only does the label size change how many peanuts people thought were in the package, but also how much they ate and how much they thought they ate.

  • When given a 60-peanut package labelled small, people ate 40 grams of peanuts.
  • When given the same package labelled medium, people ate 30 grams.
  • With packages labelled as small, participants thought they ate 20% less than with the same size package labelled as medium.

Yet the reverse wasn’t true. Smaller packages (50 peanuts) labelled small or medium didn’t affect estimates. In this case, people guessed 54 peanuts in the small and 56 peanuts in the medium. (This principle also existed in the previous study, which tested 6-pretzel packages instead of 8-pretzel packages.)

In other words, when larger packages are labeled small:

  • People think the package contains about 20-25% fewer items (even if those items are easily countable, like 8 pretzels).
  • They eat more from that small package… but they think they eat less.

When smaller packages are labelled as larger:

  • People judge there to be about the same amount in both packages.
  • People eat about the same amount from both packages.

Things aren’t looking too good so far.

Mental distraction

Study 3 found that mental distraction matters too.

While participants ate mini-sandwiches from two types of plates, researchers asked them to memorize a list of names. Each plate had the same amount of mini-sandwiches (ten), but one plate was labelled small; the other large.

Same as the first two studies, people estimated there were fewer sandwiches when the plates were labelled small. And participants’ estimates were even farther off when they were distracted.

When they were not distracted, folks recalled 8 sandwiches on small plates, but 10 when plates were labelled large (a 20% difference). When they were distracted, participants mis-estimated even more: they guessed 11 sandwiches on large plates and 7 sandwiches on small plates (36% difference).

So eating while distracted means that you don’t judge your portions accurately. Think of going to the movies and how easily you can eat a giant bucket of popcorn without noticing — now try to imagine eating that same giant bucket of popcorn while sitting alone in an empty room with it.

As with the previous two studies, though, folks didn’t mis-estimate smaller portions. People pretty much correctly estimated the plate with 8 sandwiches regardless of its label.

Nutritional consciousness

Study 4 offers some hope. People were grouped based on how nutritionally conscious they were and asked to estimate the number of mini-Oreos.

Researchers figured out nutritional consciousness using a questionnaire that asked the participants how concerned they were about nutrition intake, and how this concern was reflected in their daily lives (4). The questionnaire included questions like Do you try to make sure that the food you eat has high nutritional value?

Now to break open the bags of mini-Oreos! Each bag had about 30 g of Oreos (about 10 Oreos).

  • In the nutritionally conscious group, mis-labelling the bags small or large didn’t matter much. Participants guessed 10 Oreos when labelled small and 10.8 when labelled large. (Pretty good — much better than the pretzel people!)
  • In the not-so-nutritionally conscious group, labelling the same package of Oreos small caused the participants to reduce their estimate over 30%. Thus, people guessed 13.75 Oreos when the package was labelled large and 9.4 Oreos when the package was labelled small.


Labelling food portion sizes as small, medium, or large makes people estimate the true amount differently.

If larger sizes are labelled as smaller sizes, people underestimate how much food there is. They eat more but think they eat less.

Yet the opposite isn’t true. Labelling smaller food portions as large doesn’t lead to overestimation of how much food there is, eating less, or overestimating how much one has eaten. People don’t eat less or think they ate more than they did.

This mis-estimating is a one-way street that the researchers call guiltless gluttony.

With guiltless gluttony you can eat more, but believe you ate less. As far as you’re concerned, the reason you can’t lose weight or are gaining weight is a mystery. You truly believe there is less in the package and you ate less… while eating more. All because of package labelling.

The saving grace is that if you are more aware and nutritionally conscious, you will notice when bigger portions are labelled as small. You can protect yourself from inadvertently overeating.

Overeating Research Review: Lying (food) labels

Bottom line

Don’t assume that food producers have your best interests at heart. Don’t trust them to judge your portion sizes for you.

Don’t judge a correct portion size by the label. Use both your thinky brain and your physical fullness cues to determine when you’ve had enough.

Help your brain and body do their jobs by staying aware and mindful. The more distracted you are when you eat, the bigger the difference between reality and perception. If you’re really rushed and busy, you might chow down a meal and then wonder who stole your burger and left only crumbs behind.

The more nutritionally conscious and aware you are, the less likely you’ll be misled. Pay attention and don’t believe the hype!


Click here to view the information sources referenced in this article.

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