This is why you should cut cake into smaller pieces

Bigger portions make people overeat, that’s already well established.

A meta-analysis found that doubling a portion increases intake by 35 percent, and a Cochrane review estimated that the growing portions of food and soft drinks lead to an extra 215-280 calories consumed per day on average.

Portions can grow in two ways, however: A portion can grow in size, or by increasing the number of units in the serving.

So here’s a question for you: What would induce more eating, a super-sized sandwich, or 3 normal sized sandwiches that weigh the same as that super sized one? A mega 8-ounce chocolate bar or a package of the same weight with 8 pieces of 1-ounce chocolate treats? In other words, does increasing the volume of the food have the same effect as increasing the number of units?

To answer this question researchers from Belgium and Australia, led by Jolien Vandenbroele, conducted a series of experiments. Their findings appear in a new paper in the journal Appetite.

Visual cues 

In the first experiment 186 participants watched a video during which they could snack on chocolate brownies. The brownies were presented in different sizes (8, 16 and 32 grams), and different numbers of pieces (1, 2, 3 and 8 pieces). That enabled 12 different brownie plates, in which the total weight of brownies served varied from 8 grams all the way to 256 grams. The different plate presentations also play with brownie size vs. number: People who got 64 grams of brownies (about 2 ounces), for instance, could be presented with 8 small pieces, 4 medium pieces, or 2 large pieces. The participants were unaware that their consumption was being monitored.

And the result: When presented with more food people ate more overall, but the way the treat was presented mattered too.

For the example of the 64 grams of brownies above, when these were comprised of 8 pieces, only 18 percent of people ate the full portion, while 40 percent consumed the entire plate when the brownies were presented as 4 medium pieces, and 60 percent ate the full 64 grams when the brownies were cut into 2 large pieces.

So, the bigger the portion the more people ate, but larger slices rather than a greater number of smaller ones produced more overeating.

The second study, involving 193 participants, tested the perception of amounts as it relates to food’s piece size and the number of pieces. People were shown photos of chocolate in 4 different sizes (12.5g, 25g, 37.5g, 50g) and four different unit-numbers (1, 2, 3, 4 pieces), so that the photo could depict total portions from 12.5 grams to 200 grams.

In this study, portions made up of more units were perceived as containing more than portions made up of larger chocolate pieces, for instance, a total of 100 grams of chocolate made up of 4 pieces was perceived as having 114 grams, while 100 grams presented in just 2 pieces were perceived as 83 grams – less than their actual size.

Judging by the results so far, it seems like our mind perceives greater number of items as greater quantity, and that might be why multiple pieces adding up to a large portion don’t lead to as much overconsumption as one big oversized piece of food.  

Which leads us to study number 3. In this study 189 people were made to concentrate on either size increase or number increase before they were presented with food. This was done through showing them pictures of gradual increase in quantity of garbage bags, machine oil or water. They were shown either growth of unit, i.e., the water bottle starting at 16 ounce and growing gradually to 32 ounce, and eventually to 1.3 gallons, or growth in number, i.e., one 16 ounce bottle growing gradually to 10 bottles of 16-ounce each.

After this exercise, the volunteers watched a short movie, during which they were given a snack: brownies, much like in the first study. They were all given 100 grams of brownies (about 3 ounces) – the total portion weight remained the same – but half of the people got these as 2 large pieces, and the other half got them as 6 small pieces. The researchers calculated how much of the brownies the volunteers ate, and participants were also asked to estimate the weight of the brownies on the plate they got.

And the results: Participants who focused of changes in size seemed to estimate the 2 larger brownies plate as weighing more than the 6 smaller brownie plate. They also ate less when their plate had 2 large cakes. Those who focused on number of units perceived that the plate with 6 brownies weighed more than the 2-brownie plate, and tended to eat less when the brownies were small.

Larger or more, is there a difference?

These three studies suggest that we subconsciously quantify food on the plate, and that a larger number of pieces impress us more than a large piece of the same weight.

Ask young kids what’s more valuable, 4 quarters or 10 dimes, and their intuitive answer is invariably 10 dimes. We see the number of items much more clearly that we see size or monetary value, at least when we’re young and uninitiated.

Multiples of smaller food units can register as more food, may lead to greater satiety, and may also suggest to us that each small unit is a “normal” and appropriate serving size.

Useful tips

Divide foods you want to eat less of into small pieces: cut cakes into small portions and shape cookies smaller. When presented with a very large portion, consider cutting it to several pieces and then stare at your plate for a second.

For fruits and veggies, try the opposite and supersize them.

And although family sized highly processed snacks and drinks are sold for lower prices per weight, beware of those. Larger bottles of soda, bigger packages of snacks and supersized meals require much self-control, and make overconsumption the default.

Dr. Ayala