Unit Bias, Segmentation, and Sneaky Portion Control Tricks
You Don’t Miss the Calories You Don’t Know You Didn’t Eat
I first heard about “unit bias” from Gretchen Rubin in her book, Better than Before. I have always been fascinated by habits, and by the ingrained and unconscious qualities of most of our behaviors. However, this particular concept of the unit bias was new to me.
I’ll let Gretchen explain “unit bias” in her own words:
We tend to finish a serving if it seems like a natural portion of ‘one,’ and we tend to take one serving, no matter what the size. In a study where people could help themselves to big pretzels, people took one; when people were instead offered big pretzels cut in half, they took one half-pretzel.”
These researchers call unit bias a “consumption norm”:
People choose, and presumably eat, much greater weights of Tootsie Rolls and pretzels when offered a large as opposed to a small unit size (and given the option of taking as many units as they choose at no monetary cost). Additionally, they consume substantially more M&M’s when the candies are offered with a large as opposed to a small spoon (again with no limits as to the number of spoonfuls to be taken).”
In other words, we can’t tell – and, more importantly, don’t care – whether we’ve had a large cookie or a medium cookie, or even a small cookie. We just know we had a cookie. Our brain computes our portion intake in terms of servings, or “units,” regardless of the size of the serving.
Another consumption norm closely related to unit bias is “segmentation.” This one’s simple: if you cut food like pizza or cake into smaller pieces, your unit bias can kick in and cause you to see one cake slice (halved) as two slices of cake. Your brain doesn’t consciously put it together that these are two halves of one slice – you just see two slices.
In other words, a large part of our satisfaction and fulfillment with food is visual and mental, not physical or caloric.
I have coined my own term for this: “visual appetite.” We all do it. Even if we have developed mindful eating practices, we still have a biological tendency to rely more easily on our eyes for external portion cues, than we can reliably tune in to our internal satiety cues. We do not have calorimeters attached to our stomachs that accurately tell us when we have eaten a certain number of calories – the equivalent of this that does exist in our stomachs (producing leptin, the fullness hormone) is not informed of your diet plan, and may have a different approach than you want.
This mis-match – the combination of poor eyeballing skills and a biologically advantageous proclivity for overeating hyperpalatable foods – can be a liability for your weight loss goals, causing you to underestimate your intake, and have difficulty reining in calories.
But this inability to estimate portion size can be transformed into an asset. When you are seeking to trim excess calories from your diet, this blindspot for estimation can be leveraged to help you feel more satisfied with smaller serving sizes.
In other words, you don’t miss the calories you don’t know you didn’t eat.
Particularly when it comes to rich, snacky treats like pretzels, slices of pizza, cake, cookies, and other delectable foods, it is incredible how much less we can eat, without noticing and perhaps with even greater enjoyment, when we intentionally employ heuristics to trick our brains to our secret benefit.
Let’s go back to the example of dividing one slice of cake into two. Now… might you eat both halves? Absolutely. But – and this is a very important “but” – when people are trying to lose weight without dieting or unreasonable restriction, having two slices of cake feels positively decadent compared to “limiting yourself” to just one piece. Or worse, a half of one slice. To be realistic, it is quite likely that the same person would have had two slices of cake anyway, even if they were double the size.
This means, in practical terms, that separating food into smaller sections (“units”) can affect the overall amount that you eat, even if you help yourself to multiple servings. You may get more satisfaction out of the eating experience, but actually eat less calories.
This study’s subjects confirmed that people often prefer more than one unit, regardless of unit size:
Participants served multiple smaller units did eat less than did participants served a single larger unit, even when the overall portion size was the same, but the amount eaten was consistently more than a single unit.”
As I pointed out last week, portion control strategies do, however, reach a point of diminishing returns. Once your overall caloric intake dips to a point that your body’s alarm system is kicked into gear, your brain will actually begin producing hormones that trigger a stronger desire for – and obsession with – food. These overwhelming cravings are difficult to negotiate for important biological reasons, and often cause binge episodes that effectively erase your caloric deficit. This is a self-protective physical mechanism, designed to keep your body in equilibrium and prevent excessive weight loss. This is why it is essential that, when you cut calories, you only do it to the extent that you still feel content with food. You need to find your sweet spot.
This sweet spot zone is where “tricks” like unit bias and segmentation are going to be most effective – not if you are being overly-restrictive.
Here are a few practical ways to take advantage of this blind spot in our reasoning:
Slice food into smaller pieces. This is a simple way to increase the satisfaction of your meals (especially meals out) without eating more. If your pizza comes sliced in six large slices, it’s incredible how much more food your eyes perceive if you re-divide into 12 small slices. You may not even eat it all, because it may actually seem like too much food. That’s the unit bias kicking in – 12 slices seems like a lot, whereas six slices would have seemed socially acceptable.
Buy lower-calorie-per-serving foods. Get smart about label reading. Get the granola that’s 60 calories per quarter cup instead of 120 calories per quarter cup. You won’t detect the difference.
Buy smaller foods. Buy the smaller cookies. Buy the smaller ice cream bars. Most of the time, these treats will be no less gratifying than their larger counterparts. When I was in Italy this spring, I had a gelato on the street one day. It was incredible – I still vividly remember it. I did not think about the unit bias aspect until I arrived home and had an ice cream out in New Jersey. The gelato in Italy was served in a container the size of a shot glass (no exaggeration). The ice cream at home was in a pint-sized container. The effect of unit bias is that I did not notice how small the gelato was in Italy – in fact, my husband and I actually split it! Unless something is small to the point of the absurd (like a slice of pizza the size of a Totino’s Pizza Roll), you will enjoy the smaller version as much as (if not more than) the bigger version.
Use measuring cups and spoons and give yourself the correct serving size of carbohydrates like pasta, rice, or quinoa. We have a tendency to serve these foods in uncontrolled qualities, with a large ladle or serving spoon. The portion sizes often end up being quite large, and we don’t even know how much we’ve eaten. Simply by using a measuring cup to dole out one half of a cup, or even one cup, you could potentially be reducing your caloric intake by 50%.
Dividing treats like chips or pretzels into smaller-than-prescribed servings. If the bag says 6 servings, divide it into 10. You won’t know the difference between having 100 calories of pretzels and 150.
There are many more, but these are just some starter ideas. You can almost endlessly manipulate your visual appetite to be more satisfied with less mindless eating. It’s just more trick in the toolbox to make a healthy lifestyle easier, without getting bogged down by anxiety over “good” or “bad” foods.
Remember, however, that all the tips and tricks in the world are only bandaids if you struggle with using food for self-soothing, distraction, comfort, or entertainment. Check out this blog post to learn more about how to transform your relationship with food.
Follow-Up Questions from Last Week
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Last week in “Outsmarting Yourself: Strategies for Effortless Portion Control,” we explored the strategies for making portion control easier.
Answer the following questions about your experiences with last week’s post:
- Question 1: Do you find that you are a person who struggles disproportionately with “food reward”? How does this manifest in your life?
- Question 2: Did you try pre-packaging your leftovers into individual containers this week?
- Question 3: Did you try pre-packaging your snacks into individual bags this week?
- Question 4: What is your game plan for leveraging your portion control blind spots to your advantage this week?