Why Calorie Counting Will Always Be Flawed [Infographic]

Why Calorie Counting Will Always Be Flawed [Infographic]

You can meticulously count every single Jelly Bean or lick of peanut butter you’ve had, then calculate the number of calories you’ve burned to offset them. But this actually hurts your weight loss efforts (and sanity) more than it helps. Here’s why you shouldn’t rely on “calories in” and “calories out”.

Cake calorie image from Shutterstock

At their core, the laws of thermodynamics do not lie: if you use more calories than you take in, you will lose weight, and vice versa. It all sounds simple, except we’ve already discussed why calculating calories in and calories out as if it’s plug-and-chug maths can sabotage your weight loss efforts.

The truth is that there are numerous variables that will affect both the number of calories that your body will actually get from the foods you eat and the amount that will be expended. These infographics from Precision Nutrition simplify what’s happening in both instances.

On the “calories in” front, the first infographic discusses how not all calories from foods are absorbed. That’s because not all foods are created equal. For example, the amount of fibre a food has or whether the food is cooked could impact the calorie count. Plus, nutritional labels and how much people think they’re eating are both highly inaccurate to begin with.

The problems outlined in the second infographic get really interesting. Basically, you cannot accurately predict how many calories you’ve burned because of variations in individual metabolism, lifestyles (like not getting enough sleep, for instance), genetics, and your history of dieting. Adding to the conundrum are the overblown “calories burned” counts you may see on cardio machines and fitness trackers, along with this nasty bias called the licencing effect, where you are likely to overeat only because you exercised and now think you deserve to eat more.

Clearly, the whole “calories in versus calories out” is not straightforward. This doesn’t mean you should stop caring about calories. Let’s be clear: They still matter a lot, but not to the point of obsessing over neurotic accounting methods and detracting from your enjoyment of life.

If you’re trying to lose weight, tracking calories or macronutrients for a while will give you a better idea of portion sizes and how much you’re eating.

In the end, exercise and diet are merely two complementary pieces to the weight loss puzzle. In the words of Dr. Yoni Freedhoff, author of The Diet Fix, /”You lose weight in the kitchen, you gain health in the gym.”

Why Calorie Counting Will Always Be Flawed [Infographic]
Why Calorie Counting Will Always Be Flawed [Infographic]

[Via Precision Nutrition]


  • I’ve always had a problem with the “Calories in, calories out” thing. As an (ex-)scientist, the calorie is NOT a measure of mass. Since we are not moving at relativistic speeds, the connection between energy and weight is not obvious – and I have found no expert who is able to explain it clearly.
    A more useful value (and more easily measured!) would mass in vs mass out. Again actual composition and individual metabolism will affect how long the weight says on your body, but at least the connection is easier to make.
    BTW – a few years ago a TV presenter showed that the main way that metabolic waste (“burnt” fat) leaves the body is via CO2 exhaled. Interestingly the scientists he asked had never thought about the question because had focused on energy content rather than the actual substance.

    • A calorie is a unit of energy. Mass in vs mass out does not work because objects of the same mass do not necessarily contain the same amount of energy.

      Energy in minus energy out = energy stored.
      Mass in minus mass out does not equal mass stored.

      Unless you are trying to say 1kg of water contains the same amount of energy 1kg of sugar does.

      You probably cannot find an expert to define it because you are treating the units of measurement incorrectly.

      • I think that was exactly my point, the units are incorrect. The question is: why does energy content matter? Energy stored is NOT weight gained. As you say, energy is not weight, but M-in – M-out = M-stored; by definition. Conversation of mass is a basic principle of physics.

        If I stand on the scales with 100g of water, or a 100g of apple, or 100g of meat, or 100g of chocolate – my weight is 100g heavier than without it. Whether it is in my mouth or in my hand is irrelevant. If I eat the item then some gets digested and some leaves as solids within the next day or so. Substance leaving the body = weight drop (again basic physics).

        Now the complex part starts: The digested part undergoes some (very complicated) chemical reactions and the residue leaves my body, usually as liquid or gas. My weight does NOT drop when the energy is taken from the digested food, it drops when actual matter – atoms and molecules – leaves my body. If it doesn’t leave, for example being stored as fat molecules (or intramuscular glycogen, or fluid held in my bladder), then I don’t lose that weight.
        Weight gain (or loss) is then all about how long the substance says within your body. And for some reason the only factor most people look at, out of the possible variables, nutrients, reactions and physiological responses that may occur, is the energy content.
        As I see it, the purpose of the infographics above is to explain why this is such an inaccurate process, but it does not address why nutritionists started doing it in the first place when it so obviously flawed.
        As I said – the connection between energy and weight is not clear.

        • Energy is typically stored as fat though, that’s why we measure intake and output against weight gained. Though the food you eat does loose weight as you digest and burn the energy stored inside it, those atoms and molecules do disappear through body heat and conversion into other forms of energy and emissions of others means eg, sweat. You are stripping matter away and converting it to other things. Hence loosing weight. If I shat as much as I ate, I would never leave the toilet. I will have a 750g steak, chips and veggies for dinner and that’s just dinner, I wont do a 1.5kg shit the next morning, plus all my other food so say 2kg and I wont put on weight over a period of time. Why? because that matter is converted into energy that energy is burned because active lifestyle. Like you said its a basic principle of physics.

          I am also yet to see a weight loss programme that tell you to measure yourself once and that it. Its a measure trend over time. So counting calories is a good way to do it. you can measure things likes inputted energy vs energy output vs weight gained and lost over a period of time and use that information to calculate optimum energy inputs to achieve what ever goal you are after.
          It is in a way fairly clear, it is just radically different from person to person, so it’s not a one fits all solution.

          • You seem to still be mixing up energy and mass as if they are the same thing. Matter and energy are only the same thing when we are talking about close to light speed. Chemical and biological processes do NOT convert mass to energy.
            The food does NOT lose weight as you digest it, burning calories (an oxidation reaction) just means converting complex chemicals into simple ones. Atoms and molecules change form but they do NOT disappear. The main form of excretion is through metabolic waste in urine (dissolved salts) and breath (CO2). It is only once these substances leave the body that weight will drop [Faeces are almost entirely undigested material – that is, the part of food which is NOT digested].
            The question is; Why do weight loss programmes talk about calories? I have no doubt that they do, but why is it significant given that mass of food is a much more reasonable measure than energy content? Where is the connection? Why does measuring weight involve calories and not just weight?
            BTW – you are correct with it varying person to person. The way that a fit person processes nutrients is radically different to the way an unfit person does. The combination of foods, the heat and your individual bioflora also have a significant impact – so why is calorie content so important?

      • I have a PhD in physics, am a qualified fitness leader and have done some research in biochemistry – so, yes, I have a background in this area, although I am not a nutritionist. I still can’t find anyone who can explain the importance of calorie content or why I should care about energy when my interest is in weight. At least, not in a logical, coherent manner. Ruben Meerman was the closest with an article he did for Catalyst a year or so ago, but it still does not address the underlying issue.

  • Peter_guest is right. Physics terms get commonly misused outside of physics. Energy and mass get interchanged constantly in discussions of metabolism, burning calories, losing weight, and so on. As with all chemical reactions, there is NO conversion of matter into energy or vice versa. This only occurs in nuclear reactions or other high energy physics interactions. However, there is likely a strong correlation between Calories burned and weight lost because they both result from the same cause, the process of metabolism. If there’s more metabolic processes occurring, then there is more chemical energy from food converted to heat, and there’s also more atoms in the food that get converted to ‘waste’ products, which primarily leaves the body during exhalation as carbon dioxide. The phrase ‘burning Calories’ is shorthand for doing whatever activity leads to these metabolic processes, but using this language may very well obscure and confuse these discussions. If we want to discuss weight loss, then I agree we should focus on mass in vs mass out, not energy. Count the number of each type of atom in, and compare to what’s leaving the body. The difference will tell you weight gain or loss, not ‘energy’ gained or lost. It’s not that all the information out there is useless because it’s inaccurate, it’s just that the language is sloppy and obscures the details, and the details could likely matter.

Show more comments

Comments are closed.

Log in to comment on this story!