"Quick question: How many kilojoules have you consumed today?"

What about the number of kilojoules you consumed at breakfast? Even an estimate will do.

Most of us wouldn’t have a clue.

A study by published in the Journal of the American Medical Association in September 2014 found that that “adolescents underestimated their meals by about 250 calories (1,050kj). Adults were off by about 175 calories (730kj) on average, but one quarter thought their meals had nearly 500 calories (2,090kj) less than they actually contained.”

Just to put that into context, the recommended daily allowance for a mostly sedentary, but healthy adult, who is 180cm tall, and currently weights 77kg, would be 8900kj.

So, the obvious response would be to post kilojoule counts with the food, so that people know how much they are consuming.

It seems logical and highly rational. Give consumers information and those with the motivation to change will use that information.

Kilojoule estimates are now commonplace in fast-food shops, along with kilojoule intakes on packaging of most prepared and processed foods in the supermarket.

The overwhelming support by Australians for a compulsory health star rating system suggests that, for most of us, labeling makes sense.

And research is showing that this labeling does have some impact on consumer decision-making, but there are still many questions about what type of labeling does and doesn’t work, and on whom.

For example, in a study that looked at 100 million transactions at Starbucks in New York City, Boston and Philadelphia, those stores that had calorie labeling next to their food saw a significant calorie reduction (6 per cent) from those without.  In a different study, researchers found that the posting of calories in particular restaurants such as McDonald’s and KFC did result in a significant, but small, reduction in the calories consumed in these restaurants. The same study, however, also found evidence of the ‘halo effect’, in that people also ate more calories at Subway than any other chain, because of their belief that the food was healthier and therefore lower calorie.

Other research has shown that most people have trouble calculating nutrition information with respect to serving size and recommended amounts (Percent Daily Values), hence the call for a simpler labeling system such as the health star rating.

Researchers in this field continue to try to understand at a more detailed level why some interventions work, while others don’t. This is nothing out of the ordinary – science is constantly refining findings.

A 2014 study published in the journal, BioMed Central, highlighted the potential for exercise equivalents as a guide to calorie counts and those unaware of the negative health implications in consuming fast food.

So, instead of esoteric kilojoule counts, such as 4800kj (Whopper Value Meal), 4897kj (medium Big Mac Value Meal) or 3780kj (Ultimate Burger Meal), that require you to draw upon both your calculating knowledge, and your memory of everything you have eaten so far today, you would be confronted with something more concrete like 55 minutes of sprinting (Whopper Value Meal), or a 75 minute game of squash (Big Mac Value Meal), or, perhaps 70 minutes of fast swimming (Ultimate Burger Meal). And yes, these are estimates, but so are the kilojoule counts.

A study published this month in the Journal of Marketing Research, takes this idea of more concrete information in a slightly different direction, and shows that the inclusion in the menu of an unhealthy label, such as ‘this food has an above average level of fat or sugar’, plus a price surcharge, such as a fat tax, has a significant effect on the ordering behaviour of consumers in a restaurant, in comparison to a menu that has one of them, or none.

Avni Shah and her colleagues at Duke University in the US found that making the price increase (the tax) explicit and framing it as a penalty for choosing unhealthy food encouraged people to make healthier choices. It doesn’t prevent them from eating food high in sugar and fat if they want to, it simply gives them a more informed perspective when making their choices.

This approach shouldn’t be too controversial, it is exactly what businesses also do – provide you with the information that they believe will get you to buy their product.

What all of these findings tell us is that the provision of information is helpful, but it has to make sense to the person processing that information.

A few years ago, when speaking at an ASIC annual forum, I told the financial and consumer regulators present something that is constantly reinforced by research; that information on its own isn’t enough to change behaviour.

For people to change, they need that information to be direct, immediate and personal. Any information that requires calculation, additional effort, or is hypothetical, such as ‘this may happen to you’, results in people delaying thinking about it and acting upon it.

For many people, kilojoule counts on their own are too abstract, complex and removed from reality. What this new research is telling us is that, in addition to kilojoule counts, people need relevant information that has an impact on their decision-making. Otherwise, they will respond to their automatic responses and eat the food that we have evolved to be drawn toward – food that is high in fat, sugar and salt.

Of course it is cultural engineering to help people make choices, but we intervene all the time for the broader safety and good of society. You don’t get to choose what side of the road you drive on or the speed that you would like to travel. That’s what governments do; they intervene to modify behaviour when there is risk to the community. That isn’t ‘nanny state-ism’, it’s just what elected officials are meant to do.

There is no doubt that the obesity epidemic – and it is an epidemic, with three in five Australians overweight or obese – is one of the gravest health risks facing us. Obesity is a risk factor for a range of conditions including cardiovascular disease, Type 2 diabetes, some musculoskeletal conditions, infertility, stroke, and some cancers. All of these have an impact on families, on workplaces and more broadly, our way of life (and yes, that includes the economy).

The substantial rise in overweight and obese Australians suggests that doing nothing, blaming individuals for their behaviour or telling people to simply stop eating, doesn’t seem to be working.

If the framing of information that has been shown to have an influence on behaviour is an example of a nanny state, then every major corporation seems to be behaving like a nanny. I’m not suggesting that we remove freedom of choice, I am simply suggesting that we provide people with the right kind of information so that they can make better choices.