Beware the multipack: it may hinder rather than help your diet

Offering smaller portions is one way of encouraging people to eat less. But while a single, smaller portion does lead to less consumption, having multiple smaller portions on offer can encourage some people – notably the diet-conscious – to eat more.

Based on evidence that portion sizes have been growing since the 1970s, some researchers have speculated that this is the cause for obesity’s increasing prevalence. But correlation doesn’t equal causation. Since the 1970s, our lifestyles have also become very much more sedentary. The rise in obesity is probably a function of what we eat as well as how active we are.

Shrinking portion sizes

Nonetheless, controlling portion sizes can at least help. We have compelling evidence that smaller portions lead people to consume less, for instance. Encouragingly, a number of longer-term studies show that smaller portions have led people to lose weight.

The power of smaller portions has encouraged at least some public health agencies to actively promote related ideas, such as 100-calorie snacks. And a willingness by customers to choose smaller portions has encouraged food manufacturers to respond by providing them.

Coca-Cola, for instance added a 250-millilitre can to its range last year and already has 200mL mini-can multipacks. But smaller portions and multipacks are distinct packaging formats with subtle but important effects.

A number of other food companies have introduced large packs partitioned into multiple, smaller “snack-size” packs. The presumption is that partitioning a larger portion into smaller portions will encourage people to eat less in line with the portion-size effect.

But research shows providing multiple smaller packs leads to a paradoxical effect among the diet-conscious. They tend to eat more when offered multiple smaller packs.

In 2008, two independent research teams showed that when participants in lab studies were provided with multiple packs of M&Ms or cookies or chips, people who identified as diet-conscious tended to eat more than people presented with the same quantity in one single, unpartitioned pack.


Smaller packets can ‘trick’ some people into eating more. Mike Mozart/flickr, CC BY

But the results from the three studies (two from one team, one from the other) were equivocal. While partitioning reduced consumption among non-diet-conscious people across all three studies, the difference was statistically significant in just one. Partitioning also increased consumption among the diet-conscious in all three studies, but again the effect was significant in just one.

Mind what you eat

We conducted additional research replicating key elements of the previous three studies. We then combined our study with the previous published studies in a meta-analysis. This confirmed the operation of two opposing effects: partitioning reduces consumption among the non-diet-conscious, but increases consumption among the diet-conscious.

But does the effect work beyond the artificial setting of the laboratory? One striking feature of all the studies showing this contradictory partitioning effect was that participants were blind to the fact that their food consumption was being monitored. They were actively engaged in another study (completing a questionnaire, or evaluating advertisements), with the snacks being offered as an incidental treat.

To examine the importance of participant awareness, we did another study examining an additional sample of diet-conscious participants who were explicitly told they would have to provide an evaluation of the snacks afterwards. They no longer ate more.

It appears that the partitioning effect is sensitive to whether people are aware that their consumption is being monitored. This finding is consistent with a recent meta-analysis showing consumption is generally reduced when people are aware they’re participating in a food study.

Smaller portions do appear to help reduce consumption, but people who are diet-conscious, those who are watchful of their weight and what they eat, ought to be careful about multipacks containing multiple smaller portions. This packaging format seems to encourage them to eat more.

The effect of multipacks fits with other research showing the way food is presented can unconsciously affect consumption. If you serve the same amount of food on a small plate, for instance, it may look bigger and lead people to eat less. And tall, thin glasses look bigger than small, squat ones with an equivalent volume; they encourage people to serve and drink less.

The key is to trick the mind into eating less. As eating behaviour scientist Brian Wansink says in his book, Mindless Eating:

The best diet is one you don’t know you’re on.

If you are diet-conscious and intending to buy snacks, you’re better off buying large, unpartitioned packages, or a single small pack. But the best option would be not to buy the snacks at all.

The Conversation

Stephen S Holden, Honorary Associate Professor, Macquarie Graduate School of Management and Natalina Zlatevska, Assistant Professor

This article was originally published on The Conversation. Read the original article.

How marketers condition us to buy more junk food

Fast food giant McDonald’s has been under a cloud in recent years as its US customers turn to alternatives. In this “Fast food reinvented” series we explore what the sector is doing to keep customers hooked and sales rising.

While excess weight and obesity is a growing global concern, there has been more and more advertising and promotional effort encouraging the consumption of unhealthy food.

In many cases this marketing is targeted at children, and takes place online. In our recent study we investigated the impact of online marketing communications on children and their intention to consume unhealthy food. We found fast food ads on social networking sites can manipulate young audiences – their purchasing likelihood, their views of fast food and their eating habits.

The qualitative study included a sample of 40 Australian children who use social networking sites. Half (21) of the children were male and the average age was 14 (the youngest being 12 and the oldest 16). Their parents were also present during the interview, however they agreed not to intervene during the conversation.

A growing problem

The prevalence of excess weight and obesity among Australians has been growing for the past 30 years. Between 2011 and 2012, around 60% of Australian adults were classified as overweight, and more than 25% of these fell into the obese category. In 2013, more than 12 million, or three in five Australian adults, were overweight or obese. On top of that, one in four Australian children were overweight or obese. Excess weight and obesity is only beaten by smoking and high blood pressure as a contributor to a burden of diseases.

Despite this, the food industry is succeeding in using marketing communications to change attitudes, perceptions and perceived norms associated with unhealthy food.

Consumers are lured by surprisingly cheap deals, which are especially attractive to teenagers and young adults with low income. But sales promotions such as discounts and coupons often offer only short-term benefits to consumers and are usually not effective among middle-age adults.

However, if a promotion is offered for a long period of time (i.e. more than three months), it can actually influence customer habits, encouraging repeat purchases – for example, the $1 frozen Coke.

Similarly, sales promotions can make other brands be perceived as less attractive by customers after a period of time. For instance, the $1 frozen Coke campaigns by McDonald’s and Hungry Jack’s affect the perception of frozen Coke in terms of monetary value. Many consumers become less willing to buy a frozen Coke that is more expensive than $1. The same can be said of $2 burgers or $5 pizzas.

The role of social networks

More than half (16 out of 30) of the respondents admitted they tended to change their eating habits after repeatedly being exposed to advertisements on social networking sites.

“Yes, many people say that it is not good to eat fast food. I used to think so but not anymore. Look at their ads, they are colourful, many options and cheap.”

“I just cannot resist it… I had been looking at the ads day after day and I decided that I needed to try these”.

Interestingly, fast food was associated with socialisation and fun among young consumers.

“The ads make me feel like this is where we belong to. This is our lifestyle…where we hang out and can be ourselves.”

“This is about our culture, young, active and free. We are kids but also not kids. We are different.”

Peer pressure

Peer pressure is heavily related to eating habits, especially during puberty when there is usually a shift from home influence to group motivation. Teenagers and young adults in particular tend to choose a particular type of food under peer pressure.

More than 70% of teenagers will choose a food according to the preference of their friends. This means marketing communications promoting fast food consumption can create a snowball effect within this group of customers. For example, Jack, Sara and Park go out together. If Jack and Sara order Big Burgers with extra cheese, the likelihood that Park will order another Big Burger with extra cheese is approximately 75%. In contrast, only 2.7% of people aged over 40 choose fast food because of their peers.

It’s clear marketing efforts by fast food chains can promote unhealthy eating habits. Also, peer influence plays an important part in forming eating habits. This means the intervention of government and health organisations should concentrate on increasing customers’ attention to health issues, self-efficacy and perceived norms, and at the same time, lessening the influence of marketing efforts aimed at motivating unhealthy eating habits.

The Conversation

Park Thaichon, Assistant Professor of Marketing, S P Jain School of Global Management and Sara Quach, PhD Student, Swinburne University of Technology

This article was originally published on The Conversation. Read the original article.