– Pelle Guldborg Hansen, Ph.d.


In the summer of 2012 New York mayor Michael Bloomberg suggested banning the sale of super-sized sodas and other sugary drinks more than 16 ounces at venues across the city of New York, including restaurants, movie theatres, and street carts. The ban did not apply to diet sodas, fruit juices, dairy drinks, or alcoholic beverages. Nor did it apply to drinks sold in grocery stores. The ban, which has been labelled the “big gulp ban”, was explained by mayor Bloomberg to be a ‘nudge’ aimed at promoting more healthy behaviour, i.e., a non-invasive public policy intervention cast along the lines of the policy approach of Libertarian Paternalism by guiding consumers towards making healthier choices, while preserving their freedom to choose.


In September 2012 the ban was about to be made effective when the New York City Board of Health accepted it [1]. Dr. Joel A. Forman, member of the board and prof. of medicine, explained, “I can’t imagine the board not acting on another problem that is killing 5,000 people per year… The evidence strongly supports a relationship between sweet drinks and obesity.” Had it been made effective, establishments that failed to comply with the ban would have faced fines of up to 200 dollars. However, just one day before it was set to take effect, New York state Supreme Court Justice Milton Tingling invalidated the “big gulp ban” calling it “arbitrary and capricious” [2]. Tingling found that the board of health had overstepped the authority it was granted to fulfil its mission: protecting against and preventing diseases. That authority, he stated, does not include the power to “limit or ban a legal item under the guise of ‘controlling chronic disease.’” What’s more, Tingling noted, the regulations wouldn’t have applied equally across eating establishments. For example, sugary milk products would have been exempt, as would 7-Eleven and other convenience stores, and supermarkets [3].

Although the legal discussion is interesting in and by itself, the “big gulp ban” has raised some interesting questions at the intersection of public policy and applied behavioural science. While mayor Bloomberg has continuously defended it as a mere ‘nudge’rooted in behavioural science and aimed at promoting more healthy behaviour along the lines of libertarian paternalism, some of the most prominent advocates of this approach have rejected both its policy interpretation as well as its efficacy. Thus, first the two authors of the best-selling book Nudge: improving decisions about health, wealth & happiness (2008), behavioural economist and Nobel laurate Richard Thaler and professor of law and former advisor of President Barack Obama, Cass Sunstein, openly rejected the idea that the “big gulp ban” should be considered a nudge along the lines of libertarian paternalism [4]. Then, adding insult to injury, two of the, then, most prominent researchers in food science exploring what may be described as nudges in nutrition and health, Brian Wansink and David Just, declared the likely ineffectiveness of the proposed regulation.

In this post we argue that – contrary to the opinion of Thaler and Sunstein – the “big gulp ban” actually does qualify a ‘nudge’. We also argue that the findings of the very same scientists rejecting the likely effectiveness of the ban points to its likely efficacy in the targeted contexts. Finally, we argue that the reason for the rejection of the ban as an effective nudge may be motivated by a fear of what the implementation of “the big gulp ban” may reveal: that policy makers may apply bans on the industry in order to indirectly nudge consumers into more healthy behaviours at the cost of the seemingly non-aggressive nature of the nudge approach to behaviour change.



Throughout the world of public policy in developed countries health authorities are trying to find avenues for implementing preventive health measures to protect consumers from a range of negative health impacts caused by an aggressive food industry catering to ancient unreflected desires and preferences. This is especially the case when it comes to sugary, salty and fatty foods. Sugary soft drinks have been a central target for policy interventions traditional sugar taxes as recommended by the WHO as well as behaviourally informed versions such as the multi-tiered soft drinks levy introduced in the UK and Mexico. However, the “big gulp ban” is the first of its kind in the US, and predictably it has turned out to be controversial, especially as seen from the viewpoint of the industry.


Some expected reactions

While Mayor Bloomberg motivated his proposal saying, “I think that’s what the public wants the mayor to do” [5], the reaction of the industry was somewhat predictable: it didn’t agree. The New York City Beverage Association called the proposal “zealous” and added “Soda is not driving the obesity rates”. Coca Cola went for the standard sweet-talk of citizens by sending out a statement saying, “New Yorkers expect and deserve better than this. They can make their own choices about the beverages they purchase” [6]. In addition, the ever-present voice of Fox News found the ban flawed pointing out that, “The ban, though, doesn’t seem to take into account the obvious work-around. Want more than 16 ounces? Just buy two bottles. There’s no Big Apple ban on doing that – yet” [7]. Thus, common to these statements is that they sought to undermine both the efficacy and acceptability of the end as well as the means of Bloomberg’s intervention.

However, as few even half-way sensible people would doubt that soda is in fact driving obesity rates, the public debate quickly came to focus on the efficacy and acceptability of the means. In a response Bloomberg told that, “Your argument, I guess, could be that it’s a little less convenient to have to carry two 16-ounce drinks to your seat in the movie theater rather than one 32 ounce… I don’t think you can make the case that we’re taking things away” [5]. In particular, he added, the ban constituted a ‘nudge’ towards more healthy behaviour in the sense of Thaler and Sunstein (2008). By this he meant that the ban, while influencing consumer behaviour in a predictable way, would not take away pre-existing choice options or introduce new incentives. That is, by banning super-sized sodas and other sugary drinks of more than 16 ounces one would not be removing the option of buying and drinking more than this. Just as Fox News noticed, one can just buy two bottles. Ultimately, then, the choice set does not appear to be impaired as more than 16-ounces of sugary drinks may still be legally obtained and consumed without, it’s assumed, additional costs.


Some unexpected reactions

However, there were also some unexpected reactions. In a tweet made in the wake of this explanation, Richard Thaler declined the interpretation of the Big Gulp Ban as a nudge [4]. Cass Sunstein subsequently did the same in a talk at Copenhagen Business School. Thaler as well as Sunstein’s argument was that Mayor Bloomberg’s proposal no matter how you interpret it is a ban or mandate and hence cannot qualify as a nudge by definition.

Another unexpected reaction came from food researcher Brian Wansink, the author of the best-selling book Mindless Eating, and his colleague David Just when they criticized the ban saying:

We fear that this ban on large soft drinks will be a huge setback to fighting obesity for two reasons: … If it fails, no one will trust that the next big – and perhaps better – idea will work because “Look what happened in New York City” … Second, 150 years of research in food economics tells us, “People get what they want.” Someone who buys a 32-ounce soft drink wants a 32-ounce soft drink and will find a way to work around the ban. [8]

These reactions left the public debate in a state of confusion. Bloomberg discussed the Big Gulp Ban as a nudge, and in turn commentators came to see bans as a characteristic of the nudge approach to behaviour change. Prominent behavioural scientists, on the other hand, rejected its interpretation as a nudge as well as deny its intended effect. In the end businesses, community organizations, and the beverage industry sued NYC to prevent enforcement of the regulation. Two lower courts ruled against the city and, in June 2014, the New York Court of Appeals struck down the law.


Is “The Big Gulp Ban” a Nudge?

While the confusion about whether “the big gulp ban” qualifies as a nudge and whether it would have its intended effect had little to do with the court ruling, the confusion did subsequently seem to dampen the broader policy interest in applying behavioural insights and nudging more aggressively in public health promotion and prevention. If the efficacy and status of what seemed to be a straightforward application of nudging in public health promotion would be undermined by the most prominent advocates of this approach, then who would know what to make of it?

However, later theoretical as well as experimental work in the behavioural sciences and public health promotion and prevention, have shed light on the issues causing the confusion. Here we begin by looking into whether the Big Gulp Ban is a nudge or not – and to do this we begin by asking how the Big Gulp Ban is supposed to work, if not by banning people from drinking more than 16-ounces.


The Intervention Model: How is the Big Gulp Ban supposed to work?

To determine whether something is a nudge and whether it could work and under what circumstances, you first need to know why it works (Hansen 2019). So how is the Big Gulp Ban supposed to work? Bloomberg tried to explain this in an interview with MSNBC: “We’re not taking away anybody’s right to do things, we’re simply forcing you to understand” [9]. According to the Wall Street Journalby this, he supposedly meant that anyone will still be free to make the “conscious decision to go from one cup to another cup” [10]. we think, this is a good and charitable interpretation.

Keeping in line with this interpretation, we may take that Bloomberg by the ban particularly intended to force a new psychological decision-point into the existing settings at venues for buying and consuming soft drinks. This would be a decision-point of whether to opt-in for more, and where – for serial consumption – the preference of the consumer for more sugar is likely to have been calmed by the first 16-ounces. At the algorithmic level of psychological explanation as cast with the Dual Process Theories adopted by the Behavioural Insights and Nudging paradigm, the Big Gulp Ban is thus supposed to work by a decrease of serving size prompting a new decision point requiring a reflective decision for continued consumption at a time when much of the thirst has been quenched.


What defines a ‘nudge’?

Next, in order to determine whether the Big Gulp Ban is ‘a nudge’, we need to evaluate the interventions according a definition of the concept of ‘nudge’. But what is the proper definition of ‘ a nudge’? Originally, Thaler and Sunstein proposed that

A nudge, as we will use the term, is any aspect of the choice architecture that alters people’s behavior in a predictable way without forbidding any options or significantly changing their economic incentives. To count as a mere nudge, the intervention must be easy and cheap to avoid. Nudges are not mandates. Putting fruit at eye level counts as a nudge. Banning junk food does not. (Thaler & Sunstein 2008: 6)

However, as has been pointed out by commentators, this does actually not constitute a definition as it does not state what a nudge is, but rather what a nudge is not (Hansen 2016). Therefore, commentators have focused on providing an actual definition along the lines of the theoretical underpinnings upon which the concept of nudge is constructed by Thaler and Sunstein viz. as a non-rational influence – or as they formulate it themselves “… a nudge is any factor that significantly alters the behavior of Humans, even though it would be ignored by Econs” (Thaler & Sunstein 2008: 8), where Econs is their term for agents acting according to the standard rational model of agency found in politics, philosophy and economics, and Humans are the empirical agents studied in cognitive and social psychology as well as in Behavioural Economics.

Further, the discussion of a proper definition has also required that nudges are defined as intentional interventions rather than ‘any factor’, and here we follow (Hansen 2016) in ultimately defining a nudge as follows:

A nudge is a function of (I) any attempt at influencing people’s judgment, choice or behaviour in a predictable way (1) that is made possible because of cognitive boundaries, biases, routines and habits in individual and social decision-making posing barriers for people to perform rationally in their own declared self-interests and which (2) works by making use of those boundaries, biases, routines, and habits as integral parts of such attempts. (Hansen 2016, 174).

Thus, to determine whether the Big Gulp Ban is a nudge the simple question to ask, then, is whether it will affect behaviour change in what Thaler and Sunstein refers to as Humans while at the same time leave Econs unaffected (Thaler & Sunstein 2008); or in more details, whether it satisfied conditions (I), (1) and (2). This means that we first need to find out what a standard economic decision-model would predict.


Rational consumption with preferences over outcomes

In the standard rational model, agents hold preferences over subjectively expected outcomes. These preferences are independent of how actions leading to these outcomes are described or labelled. This is called the principle of description invariance. As a consequence, actions leading to identical outcomes are collapsed under the same disjunctive choice description. Thus, a rational agent (assuming, for now, no effects on cost or inconvenience) would not only be indifferent between obtaining 32 ounces of soft- or sugary drinks in one cup or bottle or two cups or bottles. He wouldn’t even distinguish between the two. If this is hard to imagine just think of your own preferences when getting change back at the grocery store. Ignoring costs of inconvenience, you probably don’t care whether you get €20 back as one €20 note or two €10 notes.

Further, a rational agent would be able to perfectly estimate the amount of soft drink that would suffice to quench his thirst. In so far that the choice-options presented to him require him to acquire a larger amount of soft drink than he needs – say, 32 ounces when he only needs 27 – he will just stop drinking when his thirst is quenched.

In the end this implies that a ban on 32-ounce soft drinks wouldn’t affect the buying as well as consumption behaviour of a rational agent when we, as here, ignore possible inconvenience as well as possible additional costs. At a more detailed level of analysis, costs and inconvenience can also be included in the analysis, but for the purpose of simplicity we refrain from doing that here.


So, is it a nudge?

So, what about Humans? When it comes to these empirical creatures, behavioural insights from food science, behavioural economics and cognitive psychology indicate that a ban of 32-ounce soft drinks is very likely to affect their buying and consumption behaviour exactly because (1) cognitive boundaries, biases, routines and habits in individual and social decision-making seems to pose barriers for people to perform rationally in their own declared self-interests; and because a Big Gulp Ban would (2) work by making use of those boundaries, biases, routines, and habits as integral parts to curb excessive consumption.

Beginning with condition (1), research indicates that many consumers find that (a) portion sizes are generally too large, see e.g. (Schwartz et al 2012), but that since (b) consumers tend to overestimate the amount of soft drink necessary to quench thirst, plus (c) fail to attend to how much they are actually eating or drinking when in the process of consuming, thus (d) consumers tend to finish their drinks anyway due to (e) mere inattention, or (f) sunk cost as they have now paid for too large a drink. Thus, condition (1) is satisfied. That is, although few consumers can “drink a horse”, but many tend to believe so when thirsty, and because consumers fail to attend to how much they are actually drinking when in the process of consuming, too big portion sizes will have people continue to consume even when their thirst is quenched as they will not take much notice and just keep on drinking until they hit the bottom; or, alternatively, even if consumers should notice that their thirst have been quenched at say 18 ounces, it seems that consumers tend to finish their 32 ounces now that they have paid for it, as it would be a waste to throw the rest out. Either way it creates the so-called ‘portion size effect’.

Turning to condition (2), given the intervention model of the Big Gulp Ban, it is clear that this is supposed to work by creating a “conscious decision to go from one cup to another cup” with cups aka portion sizes being smaller and thereby reduce excess consumption. That is, aligning default portion sizes better with reflective consumer preferences, i.e. (a), and creating a salient decision point counteracts (c) and reduces the effects of (d) whether caused by (e) or (f) causing consumption to approximate (a) better. Of course, this does not counteract (b), but it does mean that the intervention is supposed to work by making use of cognitive boundaries, biases, routines, and habits as integral parts of the intervention.

Finally, the fact that it is an intervention satisfied (I). In conclusion, then, the Big Gulp Ban is a nudge according to the definition of a nudge adopted here.


Can something simultaneously be a nudge and a ban?

Ultimately, then, the conclusion is that the Big Gulp Ban is actually a nudge with regard to the behaviour of consumers. However, as tweeted by Thaler, it is clearly also a ban – but, that is, with regard to how it affects industry (recall, a rational agent would not make a distinction). So, what to make of this?

The point seems to be that there are multiple agents involved in a policy intervention like the Big Gulp Ban. The first agent is the target subject, i.e., the citizen, consumer, parent, pupil, taxpayer etc. whose reflected preferences we want to support by the nudge-approach – in casu, the consumer. The second agent is the choice architect, i.e., the government agency, institution, lecturer, employer, organization, company or producer that is responsible for the choice-architecture in question – in casu, the venues offering soft drinks. The third agent is the regulator, i.e., the policy maker, government, health agency, competition and consumer authority – in casu, the New York City Board of Health.

In this model, the role of the choice architect as traditionally described by Thaler and Sunstein has actually separated into two. The regulator putting restrictions on the choice or transaction architecture (the ‘interaction tube’) through the policy intervention R2 on the one hand, and those who usually designs the choice or transaction architecture R1 within the interaction tube in question, on the other hand. From this model is it also clear how the ‘Big Gulp Ban’ creates a nudge relative to the target subject through a ban limiting the options of the choice architects as to the range of legal choice architectures. Said differently, the regulator is mandating the choice architect to nudge the target subject in one way (reduced consumption), rather than another way (increased consumption).


A philosophical twist to the story

However, knowing how much Richard Thaler loves philosophy, we may add a twist to the story. This comes by as from a conceptual point of view Bloomberg’s Big Gulp Nudge-Ban also provoked a meta- or framing- or 2nd order preference (yes, such exists!) that gives an ironic conceptual twist to the whole discussion. This is because the introduction of a Big Gulp Ban thereby led people to suddenly form preferences such as the preference of “I prefer whatever Mayor Bloomberg is trying to ban” over any alternative, as well as the more general ‘conservative’ preference of preferring “a choice between the status quo types of soft-drinks” over “a choice between the status quo types of soft-drinks, minus the 32-ounce soft-drink”. That is, suddenly people began to hold preferences over descriptions of actions and choice-sets that were instrumental or weighted relative to quite different purposes than merely quenching their thirst.

From a philosophical point of view, this changes the game. When such preferences about descriptions are formed, the principle of description invariance no longer holds. Instead, the description of choice sets over soft drinks has become an object of preference with the result that the Big Gulp Nudge-Ban seems no longer to be a nudge relative to consumer behaviour. Instead, it has become a ban due to the politicisation of the choice set.

Fortunately, there is a comeback to this – and it is to be found in condition (I) of the definition of nudge. Since Mayor Bloomberg did not intend the Big Gulp Ban to be implemented under the politicised descriptions of the choice-sets, and because the descriptions were not politicised at the time, it is actually still a nudge. This point probably only seems to matter to connoisseurs and philosophers, yet it does serve to show why thorough definitional work is often needed. So, with this issue settled, let us turn to the issue of whether a nudge like the Big Gulp Ban would be effective.

Will a Big Gulp Ban Be Effective?

Too important to test?

As mentioned in section 2.2 food researcher Brian Wansink and his colleague David Just find the Big Gulp Ban of crucial importance since future opportunities for fighting the obesity epidemic may depend on our first attempts. In fact, to Wansink and Just, it is so important a feature of the Big Gulp Nudge-Ban, that it provides a reason not to do it! However, as this reason for not testing ultimately pertains to any attempt we could think of, it is best disregarded. Still, in the light of the emphasis within Behavioural Insights on randomized controlled trials in policymaking it does point to an important reason why science and politics are often difficult to mix: scientists learn from a failed experiments – politicians get fired.


What does Wansink and Just actually mean?

More importantly, though. food researcher Brian Wansink and his colleague David Just argued that: “Second, 150 years of research in food economics tells us, “People get what they want.” Someone who buys a 32-ounce soft drink wants a 32-ounce soft drink and will find a way to work around the ban.” To us this seems a very, very, very strange comment.

Yes, behavioural economics (and history) has taught us that if somebody really wants a 32-ounce soft drink, then, yes, he will find a way to work around the ban. But even more importantly, behavioural economics has also taught us that just because someone buys a 32-ounce soft drink he doesn’t necessarily want a 32-ounce soft drink. How, or perhaps why, Wansink and Just fails to see this is a complete mystery.


How Wansink and Just’s own research suggests that the Big Gulp Ban would be effective

This is especially mysterious as Wansink and Just’s own research seems to strongly suggest that a Big Gulp ban would be effective in cutting calories in at least some settings. If they fail to agree they would have to answer at least the following four questions:


  • If people eat less calories when eating from smaller plates, why wouldn’t it be the same for a smaller soft drink?
  • If people eat more soup when portion size is larger, or even infinite, why isn’t that why many people actually end up drinking 32-ounces?
  • If people will eat even stale popcorn and do this in incredible amounts when in the cinema, then why should we expect a different outcome when it comes to soft drinks?
  • If people will eat fewer potato crisps, if a decision point is made salient by colouring a crisp by intervals, why should this mechanism work different for soft drinks than for crisps?


Of course, Wansink and Just are not the only scientists who have published research that strongly suggests the effectiveness of a Big Gulp Ban, but that will be left for future blog-posts.

Closing Remarks

In conclusion, then, the Big Gulp Ban is a nudge for consumers and a ban on industry – and it is likely one which would be effective in achieving its purpose. So why the confusing reactions from prominent scholars and scientists in the field? This remains a mystery to us, but one thing is certain. When science – behavioural science included – becomes relevant to policy and politics, there is a danger that science may become politicised. We speculate that this might have been the reason for the reluctance of behavioural scientists to support the Big Gulp Ban.  



[1] Health Panel Approves Restriction on Sale of Large Sugary Drinks, New York Times, September 13, 2012.

[2] https://www.wnyc.org/media/resources/2013/Mar/11/SugaryDrinks.pdf

[3] http://www.npr.org/blogs/thesalt/2013/03/11/174037195/judge-overturns-new-york-city-ban-on-big-sugary-sodas

[4] Richard Thaler, Tweet on Twitter, 31 May 2012, available on the internet: <https://twitter.com/R_Thaler/status/208273339507150849> (last accessed on 27 December 2014).

[5] https://reason.com/2012/05/31/bloomberg-insists-his-plan-to-limit-new/

[6] https://www.reuters.com/article/usa-sugarban-newyork-idUSL1E8H197A20120601

[7] https://www.foxnews.com/politics/nyc-plans-to-ban-sales-of-sugary-drinks-over-16-ounces

[8] https://www.usnews.com/debate-club/should-the-sale-of-large-sugary-drinks-be-prohibited/soda-ban-will-fail-and-jeopardize-future-public-health-efforts

[9] https://www.forbes.com/sites/realspin/2012/09/18/goodbye-big-gulps-in-mayor-bloombergs-new-york-hello-big-government/?sh=142457f42f1d

[10] https://www.wsj.com/articles/SB10001424052702303640104577438680975574046



Hansen, P. G. (2016). The Definition of Nudge and Libertarian Paternalism: Does the Hand Fit the Glove? European Journal of Risk Regulation7(1), 155-174. http://www.lexxion.de/pdf/ejrr/Pelle_2016_01.pdf

Hansen, P. G. (2019). Nudging: To know ‘what works’ you need to know why it works. Journal of Behavioral Economics for Policy, 3(Special Issue), 9-11.

Schwartz, J., Riis, J., Elbel, B. & Ariely, D. (2012). ‘Inviting consumers to downsize fast-food portions significantly reduces calorie consumption, Health Aff (Millwood), Vol. 31, No. 2, 399-407.


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