Joules on the menu, please

The very worthy proposal of the Food Standards Agency (FSA) that menus should state energy values is undermined by its failure to use proper measurement units.  UKMA has responded by advocating joules rather than so-called “calories” (whatever they may be).

Consultation closes today on the FSA’s proposal that restaurants (including fast food bars) should state the energy value of the food on their menus.  The purpose of this proposal would be to enable customers to relate their energy intake to their daily energy requirement – an important factor in leading a healthy lifestyle.  (In principle, if your energy intake exceeds your energy use you will gain weight – and vice versa.)

The catering industry has been wary of this proposal (not least because many fast food outlets rely on people eating unhealthily!) and the FSA’s proposal is for a voluntary rather than a statutory scheme.  It would be difficult if not impossible to enforce against the thousands of individual fish and chip shops and Chinese or Indian takeaways, so it is mainly targeted at the chains of fast food restaurants that populate every High Street, shopping mall, and motorway service station.

In its submission to the FSA, UKMA has not commented in detail on the (obviously laudable) principle of including energy values on menus, but has recommended that any scheme that is agreed with the industry should use proper measurement units that are compatible with those used in nutritional science.  In particular it has advocated the use of the joule (J) as the primary (or preferably the only) measurement unit rather than the obsolete and unsatisfactory “calorie” – or “kilocalorie” – or “Calorie”.

Unfortunately, the FSA consultation paper set a very poor example by equating the physical concept of “energy” with the misused word “calorie” – for example, writing “calorie intake” rather than “energy intake”.   This is in direct contradiction to the recommendation of the Royal Society – as long ago as 1972 – that “calories” should be discontinued – including in the media.

We give below an extract from UKMA’s submission (text in blue):

“The use of the kilojoule (kJ) vs. the use of the calorie (cal), Calorie (Cal), and kilocalorie (kcal)

We applaud the principle of giving consumers the ability to make purchasing decisions based on the energy content in food. However the consultation document’s proposed continued use of obsolete measurement units presents several issues:

The “calorie” is often confused with, or used in equivalence to, the “kilocalorie”.

A convention is sometimes applied which attempts to avoid the inevitable misunderstanding that this causes. This involves the use of a capital letter ‘C’ when “calories” are to read as “kilocalories”, such that:

1000 calories = 1 kilocalorie = 1 Calorie

Indeed, the consultation document itself is a good illustration of this issue as it uses the word “calorie” erroneously in several instances where the word “kilocalorie” or “Calorie” is intended. e.g. Annex H, 7.3 (text in green):

“Note: “kcal” is used in these statements but “calories” should be substituted if        “calories” are declared as the energy information at point of choice.”

The consultation document acknowledges that …

“36. To aid consumer understanding and contribute to consistency of labelling only one        form of expression (either kcal or calories) should be used in an outlet. “

However, this stipulation will not prevent inconsistency of labelling across different establishments.

In their 1972 report on nutritional sciences, the Royal Society identified the problem of the continued use of calories to describe energy content of food. Its conclusions remain valid nearly 40 years later (text in dark red):

“We are very much aware of the problems that arise because as a result of 30 years of education the public has an awareness of the term ‘calorie’. We cannot see any easy solution to the problem of substituting the concept that man has a requirement for the energy-yielding constituents derived from food, and this is measured in joules, …”

“We recommend that editors of journals should not allow the use of the word ‘calorie’ and list below some obvious alternatives :

calorie intake                                  energy intake

calorie requirement                         energy requirement …”

The Units Of Measurements Regulations, which implements Directive 80/181/EEC, requires that energy should be measured using the SI derived unit, the joule. The fact that the calorie is not an SI unit, and is not listed in the Directive, means that calories can only be authorised for use as supplementary indications, and should not appear more prominently than the primary measurement, in joules (J) or kilojoules (kJ).

Many packaged foods are already labelled in kilojoules (kJ).

Progressive countries such as Australia, have already adopted the kilojoule as the primary unit of energy to indicate energy content of food.


A single unit, the joule, used for all purposes regarding energy (not just food), will both benefit the consumer, and increase the general public’s understanding of the concept of energy in general.

It is for these reasons that we strongly recommend that the opportunity that this consultation presents should be taken to begin the phasing out of the obsolete unit “calorie” in favour of the “joule” (which incidentally is named after the British scientist, James Prescott Joule).




Report of the Subcommittee on Metrication of the British National Committee for Nutritional Science

Proc Nutr Soc. 1972 Sep;31(2):239-47.

[UKMA submission ends]

Further comment

Some have argued that the general public is familiar with “calories”, and to replace them with joules would be confusing and would reduce the effectiveness of the proposal to include energy values on menus.  This is to patronise the general public and underestimate their intelligence.  It is not difficult, for example,  to remember that the average daily energy requirement of an adult male is approximately 10 megajoules (10 MJ) and hence to relate that to a meal of, say, 4 MJ, or a bottle of wine at 2 MJ.  Moreover, to continue the dumbing down of energy information by using non-scientific units helps to maintain the gulf between the educated scientific community and people who have to rely on the popular media for their information.

The question of how best to measure energy (and also power) is a theme to which we shall return in a forthcoming article.

Technical footnote:

What the above Royal Society quotation does not explain is the reason why the joule is a better unit than the “calorie” (in all its variations).  This is because, whereas the value of the “calorie” is determined experimentally (by heating water), the joule is defined in terms of other SI units.  Thus, since energy = force x distance, a joule is a newton times a metre, or in other words the quantity of energy needed to accelerate a mass of one kilogram at a rate of one metre per second squared over a distance of one metre.  Similarly, a joule can be directly related to the watt (1 W = 1 J/s).  By contrast  the “calorie” is simply an unrelated anomaly that – unfortunately – has gained some currency in the popular media and some parts of the weight-watching industry.  It should be phased out as soon as possible, and the FSA should be helping in this – rather than prolonging its life.

34 thoughts on “Joules on the menu, please”

  1. ‘Weight watchers’ have a point system which combines a measure of the amount of saturated fat with energy intake. It actually works out that a point is about 300 kJ (actually its 70 kcal but I round it to 300 kJ) or 4 g of saturated fat. It works by reckoning both e.g. a meal with energy content of 1.2 MJ and 8 g of saturated fat would be about 6 points.

    The daily allowance during a fat reducing diet varies with body weight but it’s about 30 at 100 kg. The WW regime is aimed at 10% loss in body mass over 8 weeks.

    It’s just a pity they don’t seem to recognise how much easier all this is in SI units!


  2. Great submission . Concur absolutely with the point being made. I have suggested this approach many times to the FSA and never been given the courtesy of a reply let alone actioning this simple idea.

    Recommend that the technical footnote be amended to show the correct unit symbols. As ISO 1000 points out unit symbols are always printed in upright font even if the surrounding text is being printed in italic. [Quite right. We have amended it accordingly – Editor]


  3. An excellent and coherent disposition in favour of using the joule, again indicating the logical interconnectedness of the SI measurement


  4. People often claim that they want to stick with imperial measures because they “understand” them. But calories are a great example of a unit that people claim to understand, when in fact they do not. Advertisers prey on our lack of understanding to promote “calories” as being bad (hence low-calorie foods from the weight-loss industry), and “energy” as being good (for example energy drinks). How many consumers really appreciate that calories and energy are the same thing? Surely with soaring obesity rates there is a need for a public education campaign. That cannot be undertaken seriously without retiring the woefully outdated energy unit “calorie” and replacing it with the international standard joule.


  5. The apparent refusal by the FSA to replace the calorie with joule may be motivated by the same thinking as the department of health resisting the centilitre in place of the “unit” of alcohol.
    Government departments tend to draw upon the techiques of advertising for publicity campaigns. They are more used to manipulating public perception rather than informing it.
    The calorie and “unit” are buzz words used to connect with an otherwise apathetic audience who lack curiosity or interest in a proper understanding.
    The aims of such campaigns may be laudable but it raises the question as to whether the ends justify the means.
    A weak understanding of basic science must underpin a poor understanding of basic nutrition. Like the wider issue of a single system of measurement, it isn’t the only factor but it should at least be recognised as a key enabler.


  6. The British Science Association doesn’t want to take a position on this matter.

    In a letter dated 17 March 2010 from the BSA’s Chief Executive, Sir Roland Jackson he states “I have to say this is an area in which the British Science Association does not take a position”.

    Way back in 1972 The Royal Society recommended doing away with the Calorie/calorie/kilocalorie; now almost four decades later the British Science Association doesn’t support this.

    Considering this position, does the BSA support the speedy completion of metrication in the UK?


  7. Has the BSA given any reason for not having a position on this? Surely it would work in their favour somehow if they supported this proposal. Don’t say that this is another ignorant refusal against progress. Seems to be a British trait which needs to be stopped.


  8. The British Science Association (BSA); no reason was given.

    In the letter dated 17 March, Sir Roland Jackson the Chief Executive of the BSA did go on to express his personal views about this matter.


  9. It’s now the responsibility of health departments to ‘Shed Calories’.
    The statement below is from the Food Standards Agency’s website
    “[Thursday 30 September 2010]
    Responsibility for nutrition policy will transfer tomorrow (1 October) from the Food Standards Agency to the Department of Health in England and to the Welsh Assembly Government in Wales.
    These changes will mean that the health departments in these countries will be responsible for:
    *nutritional labelling
    *nutrition and health claims, dietetic food and food supplements
    *calorie information in catering establishments
    *reformulation to reduce salt, saturated fat and sugar levels in food and *reducing portion size (including in catering)
    *nutrition advice, surveys and nutrition research
    The Department of Health will also be responsible for supporting the work of the Scientific Advisory Committee on Nutrition (SACN).
    In England, the transfer to Defra of food labelling and food composition policy (where not related to nutrition or food safety) has already taken place.
    The devolved administrations are considering whether they want to make any other alterations to their current arrangements for food policy.”


  10. So, they mention England and Wales, but who now has responsibility for food labeling in Scotland and Northern Ireland?

    Let’s hope this is an opportunity for the organizations newly responsible for nutritional labeling to be persuaded to adopt “joules” instead of “calories” or “kilocalories”.


  11. “Who now has responsibility for food labeling in Scotland and Northern Ireland?”

    Food labelling policy in Scotland & Northern Ireland is currently still the responsibility of the FSA.

    Unfortunately, I cannot see the recent changes in England & Wales having even the slightest effect on the use of “calories” in food labelling


  12. 19 February 2011
    Today’s Daily Mail has an article – Health Secretary Andrew Lansley, says Calories on menus could come into effect as early as September.

    “Mr Lansley set up the Food Network, a collection of food industry leaders and consumer bodies, to draw up voluntary measures to improve the health of the nation under a so-called ‘responsibility deal’.”

    The Department of Health has NOT had a public consultation on this.


  13. The British Nutrition Foundation’s Education News (issue 61, March 2012) has an excellent poster, it shows plates of different meals and the energy values are in kJ.
    The word calories does not appear. The values in kcal are shown as a supplementary unit. I have an paper copy of the poster. The following link may assist, however I don’t see an online version of this poster called Small change, big difference:-


  14. Use joules …
    The editor of the Wellcome Trust’s education resource the ‘Big Picture’ has sadly failed to use the SI unit for energy.
    On page 3 of the latest issue, which is about plants, there are the following:
    “387 calories in 100 g table sugar”, and “77 calories in 100 g of potato”

    It’s disappointing that, in what is an excellent publication for schools and colleges, the editor has used ‘calories’; failing to give the energy values in SI units.


    [BigPicture Issue 24 Summer 2016 published by The Wellcome Trust,
    ISSN 1745-7777.
    Address: The Wellcome Trust, 215 Euston Road, London, NW1 2BE and]


  15. Published today (24 June 2018) by Health and Social Care Secretary Jeremy Hunt …
    New measures to halve the number of obese children by 2030.

    “ The Department of Health and Social Care will consult on introducing clear, consistent calorie labelling on menus in restaurants, cafés and takeaways, so parents can make an informed choice about what their families are eating. ”

    The “Childhood obesity: a plan for action – Updated 20 January 2017 ”

    This document does include the sentence “ … at its root obesity is caused by an ENERGY IMBALANCE: taking in more energy through food than we use through activity. ” [The capital letters have been put in by me!]

    It includes reference to ‘sugar targets’, ‘calorie caps’ and ‘calorie intake’.
    The document mentions the work of HEALTH EDUCATION ENGLAND which has updated existing materials and its ‘E-learning for Health Platform’

    I haven’t checked this E-Learning site to see if NHS professionals are still taught to use calories (kcal).

    Above you’ll see it was in 1972 The Royal Society recommended doing away with the Calorie/calorie/kilocalorie.

    In 2018 what is the official NHS position?
    In 2018, in schools and their exams, calories are still used; except for Physics where the proper unit for energy is used!


  16. Hospital dietitians and nutritionists continue to use kilocalories.
    It’s very difficult to get them to change and use kilojoules.
    Today I saw a small display for Nutrition and Hydration Week.
    The display was at Redditch’s Alexandra Hospital (run by Worcestershire Acute Hospitals NHS Trust). Like last year all the (food) energy values were in ‘kcal’; nothing at all in ‘kJ’.


  17. Political Party ‘promoting’ the calorie!
    2019 Liberal Democrat Manifesto:
    ” Require labelling for food products, in a readable font size, and publication of information on CALORIE, fat, sugar and salt content in restaurants and takeaways. ”

    Almost half a century ago The Royal Society identified the problem of the continued use of calories to describe energy content of food. [Details in the article above].
    How many members of The Royal Society, and its employees are aware of this report published in 1972?
    How many members of the Liberal Democrat Party and also those thinking of voting LibDem. are aware the continued use of calories is a problem?

    *Do any of the other 2019 Election Manifestos feature the use of calories?


  18. Mary:

    This comment may come a bit too late for the UK as/if it’s leaving the EU, but food labelling is regulated across the EU by the European Commission, with the cooperation of the member state governments, of course. I’m sure a move to drop calories and replace them with joules could well be tackled at the ‘European’ level. The fact is that many if not most other European countries also use calories. The problem is it’s so ingrained.


  19. Include alcoholic drinks …
    On 21 January 2020, Hansard Volume 801 records:
    Health: Alcohol Abuse; Question asked: 2.46 pm by Lord Brooke of Alverthorpe….

    A COMMENT IS PROVIDED BY: Baroness Williams of Trafford

    “Under EU regulations, companies do not have to put the calorie content on any drinks with an alcohol volume above 1.2%. I utterly agree with my noble friend that, if people knew how many calories they were consuming in just a glass of wine, they might think twice about how many glasses of wine or other drinks to have. A fact for today is that some canned cocktails contain the equivalent of six Krispy Kreme doughnuts’ worth of calories”.

    It’s sad she uses ‘calories’. Wikipedia says ‘ she has a BSc in Applied Nutrition ’
    Perhaps she is unaware of what The Royal Society said about half a century ago.


  20. More government announcements about obesity … more calories!
    Public Health England published a report yesterday:
    On page 38 – Drivers of Obesity …it says ‘It is estimated that on average adults in England are consuming 200-300 excess CALORIES per day’
    and ‘In combination with CALORIE deficit diets, physical activity can support maintenance of weight loss. ‘
    [I put it in CAPITALS].
    I can see no use of the proper terminology – what was recommended way back in 1972.


  21. @ Philip 2020-07-25 at 19:25
    The French Calorie reigns supreme in the eyes of PHE, the media and our saviours the consumer groups!
    Britain only wants to be British when it fits the agenda, French (calories) trumps British (Joules) when it suits, is too much trouble to try to change or just out of pure ignorance.
    If the EU were to vote on that issue now, without UK support the French would never get to use the calorie again but UK could carry on. Interesting that.


  22. The daftest thing about this is it would be just as easy to use the word “energy” instead of “calorie” (and the similar “power” instead of “horse power”) in most instances. It would create a better understanding that energy content is the subject, not trying to “count calories” maybe giving the impression there are some little granules or something in the food.


  23. Today’s Government press release:
    One bullet point is:
    ‘ •CALORIES to be displayed on menus to help people make healthier choices when eating out – while alcoholic drinks could soon have to list hidden ‘liquid CALORIES’ ‘
    *Calorie labelling – new laws will require large restaurants …
    *Alcohol calorie labelling – a new consultation will be launched before the end of the year …
    The recommendation by The Royal Society (in 1972) is still being ignored; it’s probably an absolute waste of energy to submit The Royal Society’s view as a contribution to this new consultation.


  24. I submitted comments about this yesterday to something called “Government Digital Service” Support.
    I do not expect much even though I requested a reply, it has never worked before.
    When I entered the word “metres” it told me I spelt it wrong, so that about sums that up.
    Posting that link just now I see /en-us/ in there, so no prospect of using British English then?


  25. @BrianAC

    What, you never heard about what an Imperial power can do?
    USA! USA! USA! Make America Great Again! 😉

    Man, I cannot wait until the election here in November.
    What scares me is what can happen between then and Inauguration Day for Joe Biden.
    You-know-who is capable of anything and everything.

    I seem to recall a time back in the day when Microsoft Word would try to “correct” words like “colour”, “neighbour”, “cheque”, “kerb”, “tyre”, etc. What a tragedy.

    Well, fingers crossed we can get some sanity back here in the good ol’ US of A next year and maybe at least pass legislation to allow metric only packaging on goods. That would be a tiny start, anyway!

    From across The Pond in solidarity …


  26. Ezra wrote “Well, fingers crossed we can get some sanity back here in the good ol’ US of A next year and maybe at least pass legislation to allow metric only packaging on goods.”

    I’m sure Metric Views readers like myself will find nothing to disagree with in the above quotation from your comment. As far as political comments are concerned, be they about the USA, the UK or wherever, the UKMA generally maintains a neutral line on political issues, as it did on the British situation re membership of the EU. Just sayin’, as you might say!


  27. Ezra should review US history with a stronger magnifying glass. Going back to 1789 with the founding of the United States and the Americans even playing a role in the development of the metric system, every opportunity to move forward was always lost. Even to the point of the US Congress never adopting a standard even though it is called for in the Constitution.

    Whether the US was run from the left or from the right very little changed in the governance of the country and even with the momentum at its strongest in the 1970s there was never a political motivation from either side towards metrication. The chances of a switch in government will not bring about any hope for metrication.

    The American media, the guardians of the status quo would have a field day if any serious contender to the presidency ever announced a desire to metricate. Metrication remains voluntary but those who do volunteer to metricate are labeled unpatriotic and those large industries that have faithfully metricated have to not only keep it a big secret from the public but have to pretend to not be metric and put on a USC face for the media and public.

    The US for the foreseeable future will remain a hybrid company with industry using metric behind the scenes and presenting a USC face for the ‘muricans.


  28. On the issue of ‘Calories on the menu’ I think we are going to loose out on this big time.

    From 1st January 2021 there will be no obligation for UK to use the very English Joule on UK FPL unless it was specifically put into, and not removed from UK law by the ‘great’ repeal act, even then it will be ignored.
    UK will be free to use the French Calorie on its own without the contamination of the great English Joule.


  29. This is a reply from my MP. [ Rachel Maclean MP ]
    ” The rules that the UK must follow on food information are set out by EU Regulations. These cover labelling and presentation, selling and advertising of food stuffs. Currently there is no specific regulatory requirement to provide information on the environmental impact of production methods.”
    And … ” It is imperative that consumers are provided with the necessary information to make informed choices. After the transition period, responsibility for legislation on the issue will revert back to the UK. The Government has stressed that it will investigate ways to ensure consumers have a clearer understanding of the labelling and marketing of food products in the future.”
    There is nothing about ‘shedding calories and promoting the use of joules’.
    Nothing about following the advice of scientists (The Royal Society).
    And nothing about the Government insisting that the unit joule is used in all areas of the school curriculum to enable students to gain a much better understanding of energy.


  30. The Government has announced today there will be a ‘New Office for Health Promotion to drive improvement of nation’s health’. Here is the link:
    I wonder whether the Government will put ‘Joules on the menu’ plus ensure joules (and kJ and MJ)appear in all their documents. Unfortunately, I don’t think the Government will bother to archive (or shed) calories yet.
    When, or IF, the Government decides to have a ‘consultation’ on this, then perhaps UKMA will be asked to submit comments. Of course, the Government needs only to look at The Royal Society’s recommendations made in 1972.


  31. Re: 29 March (MetricViewer)
    The New Office for Health Promotion
    Three months ago I asked my MP to raise the issue of using joules (and not calories) with the Department for Health and Social Care. Despite several reminders, I’m still waiting for a response.
    And today the following was published:
    It is an Independent review for Government.
    -Food-Strategy-Recommendations-in-Full.pdf which includes calories; I didn’t see any reference to joules.


  32. Re: 29 March 2021
    The new Office for Health Promotion
    My MP eventually received a reply.
    A letter from Jo Churchill MP (Parliamentary Under Secretary of State for Primary Care and Health Promotion, at the DEPT. OF HEALTH & SOCIAL CARE dated 30 July.
    “We know that eating out accounts for a significant proportion of people’s energy intake. When eating out, however, there is limited access to energy information, making it difficult for consumers to identify healthier options for themselves and their families.
    In 2018, as part of our measures to improve diets and reduce obesity, we consulted on mandating calorie labelling in the out-of-home sector. In response to feedback to the consultation, we have confirmed we will introduce legislation to require large out-of-home sector businesses – that is, those with 250 or more employees – to calorie label the food they sell. The consultation included a question about kilojoule content being displayed alongside information on calorie content.
    The consultation feedback showed that kilojoules is a unit of energy measurement used by only a minority of the population; we therefore believe there is little benefit in requiring kilojoules to be displayed alongside kilocalories.
    We have consulted on how the policy on calorie labelling should be enforced, and we have published our response. The outcome of the consultation can be found at by searching for ‘calorie labelling for food and drink served outside of the home’. Regulations were laid in Parliament on 13 May. The regulations and explanatory memorandum can be accessed at”


  33. Today I complained to the BBC about the use of BTUs in a programme.
    Details: 5 October 2022, BBC Radio 4, 09:30 ; a cooking programme, called ‘One Dish’.
    I expect I’ll receive the standard type of response.

    Cheers, Philip


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