this is a montage of food

Calories vs. Kilojoules: Why the Kilojoule is an Ineffective Measure if You Want to Stay Thin

Metric and imperial – will the war ever end? As a child, I spent two years in the American school system, learning about inches, quarts, pounds and dimes. Then it was back to the Australian school system for me where I learnt about centimetres, millilitres, kilograms and ten cent pieces. To make things even more confusing, I was transferring in grade school, when many of these important measures are first learned and committed to memory.

Bar far, the metric system is superior for measuring.

No, no… don’t get mad – we all know it’s true. It makes a lot more sense, for a start. It’s quite funny because things only started to get metric here in Australia in the 60s, meaning that half the population is still very confused daily.

Technically, the calorie and the kilojoules are BOTH part of the metric system. The calorie was first defined by Nicolas Clément in 1824 as a unit of heat, deriving from the Latin word calor meaning “heat”.

Sadly – and much to my horror and chagrin, calories have “now been superseded in the International System of Units by the joule” according to wikipedia. The site does go on to mention “in spite of its non-official status, the large calorie is still widely used as a unit of food energy in the US, UK and some other Western countries.”

And this is where my rant comes in (you knew you were about to get one of my rants, didn’t you?).

For my money, the calorie is by far the more efficient method of measuring the energy vales of food. Why? Because it’s a smaller unit. For this reason, I am also in favour of the kilogram versus the pound, but that’s a whole other story – we don’t need to count those hourly and daily, do we?

It’s easy for me to understand that I should be eating 300 to 400 calories for lunch, but my brain fades when the figure turns to 1260 and 1680. My mind automatically tends to round those figures up, saying, “well, ok, that’s approximately 2000 kilojoules”. Every day I can eat 7560 – so if my burger is 1570 then how much is left?

Kilojoules will drive you insane.

“One calorie is approximately 4.2 joules. The factors used to convert calories to joules are numerically equivalent to expressions of the specific heat capacity of water in joules per gram or per kilogram. The conversion factor depends on the definition adopted.”

Righto then.

So how do nutritionists measure the amount of calories in your thickshake?

First, they actually burn the food in a bomb calorimeter, which is a similar to a box with two chambers, one inside the other. The nutritionist will weigh a little bit of the food and put a sample of it onto a dish, and into the chamber of the calorimeter.

From Nutrition for Dummies “They fill the inner chamber with oxygen and then seal it so the oxygen can’t escape. The outer chamber is filled with a measured amount of cold water, and the oxygen in the first chamber (inside the chamber with the water) is ignited with an electric spark. When the food burns, an observer records the rise in the temperature of the water in the outer chamber. If the temperature of the water goes up 1 degree per kilogram, the food has 1 calorie; 2 degrees, 2 calories; and 235 degrees, 235 calories — or one 8-ounce chocolate malt!”

The argument from lots of nutritionists is that this is an inexact science, because who is to say that every human body burns calories in the same way. My body is always burning calories but does it burn more when I am awake, more in summer? More on Tuesday and less on Thursday?

I dislike kilojoules – we have this wrong in Australia. Switch to calories – oh fair country of mine!

Do you agree? Do you find kilojoules difficult to measure?

Great photo by chotda thanks


4 thoughts on “Calories vs. Kilojoules: Why the Kilojoule is an Ineffective Measure if You Want to Stay Thin

  1. I’ve come to Australia a number of times, but really never paid attention to the labels. This last time, I’ve stayed on a one year work/holiday visa and (because I’ve got a heart condition -no caffeine- and allergies now) I have to pay attention to the labels this time.

    (Don’t even get me started on the caffeine thing here…It seems like it’s not a requirement to put on the label whether or not caffeine is present. All the coffee here says nothing unless it’s specifically marketed as Decaf – then it’s kinda self-explanatory. Back home we have flavored coffees that are caffeine free, but not labelled decaf….I’m so…un-coffeed here.)

    Note: I don’t count calories at home. Never had a need to. My metabolism is a force to be reckoned with.

    When I saw kilojoules everywhere, though, I started laughing. The whole system just seems ridiculous. When I asked people why they were measuring their food in kilojoules…they had no idea. Just because “it was” and that’s “what energy is.”

    At least when you ask most people back home what a calorie (or kilocalorie is) they can recall something from grade school or their fitness programmes. So far, the most intelligent answer I’ve gotten on kilojoules here is a guy who went into this long explanation about James Joule and how heat is converted into energy and his own personal fascination with light bulbs.

    But food?

    In order to try to figure out why people thought this was a more effective way of measuring food, I’ve gone and read articles, downloaded fitness apps and done all sorts of things I normally wouldn’t bother to, because it’s ri-di-culous.

    My favorite is a PhD endorsed app that gives you a list of common foods and drinks, and then a list of common actions and activities.

    Apparently, in order to maintain my kilojoules balance for the day…After drinking one Guinness, I could play video games for one hour and 46 minutes.


    But wait…After three small doughnuts (which normally would have less calories back home than a stout beer), I would have to play video games for SIX hours and 34 minutes to maintain balance.

    So…Australia has super unhealthy doughnuts, a totally fucked system of measurement for food and some pretty intense video games.

    But I still don’t see how kilojoules is more effective than calories.

    • Hi Tara-

      What a great comment – this totally made my day. I know – kilojoules are STUPID!!! You’ll see a million posters here telling you that the average adult daily kilojoules intake is 8700 and that the burger you juts at was 2060 kilojoules. It hurts my brain trying to work it out – and given that Australia is a nation of big-fat-fatties … I am not the only one!

      Thanks again for your remarks. You are right – it is a totally f****ed system of managment.


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