Why the Calories In, Calories Out Argument is False (How to Eat Well and Live Right)

by Tom Ewer

Back in 2009 I did quite a lot of running and followed a pretty strict diet.

I would calorie count down to the last gram of food, keeping a detailed log of everything I ate. It was utterly ridiculous. However, it seemed to be effective — over the course of nine months or so I lost nearly 30lbs and was the lightest I have ever been in my adult life.

It doesn’t mean that my method was optimum though. After all, if you’re running 20-30 miles per week and eating less than you normally would, the weight is bound to fall off you. Back then I subscribed to the calories in, calories out myth like most people do. Fortunately, I have since seen the light.

In this post I want to reveal the fallacy that is calories in, calories out, suggest that you do away with calorie counting altogether, and finally present a more enjoyable, sustainable and intuitive method for weight loss.

Defining the Calorie

The calorie (or to be precise, the kilogram calorie or kcal) is a unit of energy that was defined by the French physicist and chemist Nicolas Clément in 1824. It is the amount of energy required to raise the temperature of one kilogram of water by one degree Celsius.

But what does this have to do with food? Well, the human body requires energy in order to operate. Everything from brain activity to blood flow requires energy, which is where the calorie comes in.

Conventional thinking assumes that the interaction between food and the human body is as follows:

Calories In – Calories Expended = Calorie Deficit/Surplus

For example, let’s say your body requires 2,000 calories every single day to keep things ticking. If you consume 1,800 calories then you will be at a calorific deficit and the body will seek the necessary extra energy from another source (such as your fat reserves or your muscle mass). Conversely, if you consume 2,200 calories, your body will store the surplus energy as fat.

Many popular diets are based upon nothing more than a simple calorie deficit. We know that a pound of fat is equivalent to approximately 3,500 calories. Therefore, if you enforce a calorific deficit of 3,500 over the course of a week, you should lose a pound of fat.

It’s a simple concept and makes dieting straightforward (in theory) and highly marketable. If you want to lose weight, consume fewer calories (and eat our “specially formulated” and wildly overpriced meals while you’re at it).

However, the theory is fallacious at best. For those of us who are willing to think beyond the calorie, a greater understanding of the effect of food on the body can enable us to lose weight without putting ourselves through grueling calorie-controlled diets.

Exploring the Three Main Nutrients

Calories are all alike, whether they come from beef or bourbon, from sugar or starch, or from cheese and crackers. Too many calories are just too many calories.

~ Fred Stare, founder and former chair of the Harvard University Nutrition Department.

Fred’s made a fool of himself.

The theory that the number of calories you consume vs. calories you expend determines your weight is false. In reality, the equation is far more complicated than that, due to the fact that human beings are incredibly complicated biological machines. If you take more than a moment to contemplate the notion that a unit of energy as simplistic as the calorie can precisely determine the makeup of your body, you’ll realise just how absurd conventional thinking is.

In reality, the way that different types of food influence the chemical reactions within our body has a huge impact on how many of the calories your consume will ultimately be converted into fat.

Let’s start by considering the three main nutrients we consume: protein, fat and carbohydrates.


Protein contains 4 kcals per gram.

You’ll find it in animal sources such as meat, fish and dairy products. However, protein can be found in a wide variety of other sources such as whole grains, legumes, nuts and seeds.

Protein is the second most abundant molecule in the body (after water). It is required for a number of functions within the human body — everything from building and repairing muscle tissue to replicating DNA. It cannot be wholly synthesized by the human body and as such is essential for life.

The body is unable to store protein for a long term period. Excess protein can be converted into alternative energy sources (such as glucose) or is excreted in urine. These processes require energy.


Fat contains 9 kcals per gram.

It is actually a general term for a number of different compounds that share key characteristics. In terms of what you eat, fats are found in a wide variety of sources such as oils, butter and nuts.

Fat has a number of functions within the body. It is most commonly understood to be a source of energy (within fat reserves), but it is also vital for the absorption of certain vitamins, maintaining healthy skin and hair, maintaining body temperature and even providing shock protection for the body’s organs.

The ingestions of fat is largely unnecessary for life. The human body only requires two types of “fatty acids”: alpha-linolenic acid (an omega-3 fatty acid) and linoleic acid (an omega-6 fatty acid). Foods such as fish, eggs, certain oils and leafy vegetables contain these essential fats. Theoretically, you could take omega 3 and omega 6 supplements and live without any additional fat in the diet (although I wouldn’t recommend it).

Fat can be stored within the body then converted into glucose and used at any point in the future as an energy source. You’ve no doubt come across many people who attempt this (the storage part, not the energy usage part).


Carbohydrates contain 4 kcals per gram.

You’ll find highly concentrated numbers of carbohydrates in a wide range of refined foods such as bread, pasta, breakfast cereals, candy and chocolate. You can also find it in unrefined foods such as beans, tubers and rice.

Carbohydrates are typically broken down into glucose to be used as energy in the body. They are what your body will first call upon when it wants to do something beyond the functions that require protein or fat. That’s why runners “carb-load” before a marathon — to maximize the amount of energy stored within the body for the huge effort ahead.

Carbohydrates are completely unnecessary for life. You can exist entirely without them. If you consume no carbohydrates, your body will synthesize the necessary glucose from the available protein and/or fat in the body.

Dispelling the Calories In, Calories Out Myth

If you’ve got this far then your intuition may have already convinced you that the calories in, calories out myth is a fallacy. While conventional thinking states that your body will treat a calorie of protein like a calorie of fat like a calorie of carbohydrate, nothing could be further from the truth.

Let’s start with protein. Its primary function is to make your body fit and strong. Protein is not a good source of energy — it has to go through a process of synthesis to be turned into glucose, while the rest is lost in the urine. Furthermore, a higher percentage of calories are lost during the digestion of protein when compared to fat and carbohydrates. On a theoretical level, this effectively means that eating 100 grams of protein will make you no fatter than eating 80 grams of carbohydrates.

Furthermore, it has been argued that protein increases satiety, increases the metabolic rate, prevents muscle wastage and promotes muscle growth. Incidentally, more muscle requires more calories.

But what about fat? While it may be demonized by dieters across the world, fat is necessary for human life and really rather good for you — especially if you stick to the essential fatty acids. You need fat.

What you don’t need are carbohydrates. They just can’t wait to get you fat. Excess carbs are converted into fat and stored for later usage. The only problem is that you probably won’t use that spare fat as you’ll be too busy consuming more carbohydrates.

When it comes to carbs, your body is living in the past, when food was scarce and excess fat stores were a good thing. It doesn’t know that you’ll have just as many carbohydrates available to you tomorrow as you did today.

While I won’t suggest that you eat zero carbohydrates (as certain carb-heavy foods are rich in vitamins and minerals), if you kept your consumption down to a very modest level (say 100g per day) you’d probably be far healthier than you are now and at no risk to your health.

Intuitively, one might assume that a “normal” person embarking on a high protein, moderate fat, low carbohydrate diet would lose weight. But how does that relate to the calories in, calories out myth? For instance, would someone eating the exact same amount of calories but with a far greater consumption of carbohydrates experience the same amount of weight loss?

Scientific Evidence Against Calories In, Calories Out

A number of recent studies have concluded that a diet low in carbohydrates can result in greater fat loss when compared to alternative (yet calorically comparable) diets.

In 2003, a study conducted by Green et al. at Harvard University observed participants over twelve weeks as they followed one of three diet regimes:

  1. A low fat diet
  2. A low carbohydrate diet with the same amount of calories
  3. A low carbohydrate diet with 300 more calories per day

The first group lost 17lbs on average, the second group lost 23lbs and the third group lost 20lbs. Greene concluded that, “There does indeed seem to be something about a low-carb diet that says you can eat more calories and lose a similar amount of weight”.

In fact, the study proved the calories in, calories out argument wrong in two separate ways. Firstly, diets with identical calorie amounts resulted in drastically different outcomes. Secondly, the third diet’s total excess of 25,200 calories compared to the other two diets should have resulted in a net weight gain of 7.2lbs, as opposed to a loss of 3lbs (compared to the first diet) or a gain of just 3lbs (compared to the second diet).

In 2004, a study conducted by Yancy et al. for the Annals of Internal Medicine concluded as follows:

Compared with a low-fat diet, a low-carbohydrate diet program had better participant retention and greater weight loss.

So what you eat (rather than simply how much you eat) can not only affect your weight, it can also affect the likelihood of you sticking to a particular eating regime.

Anecdotal Evidence Against Calories In, Calories Out

I am walking, talking evidence of how fallacious the calories in, calories out argument is.

I’ve already mentioned that I married a high-mileage running routine with a calorie-controlled diet in 2009 and lost a lot of weight as a result. What I haven’t mentioned is that in the latter part of 2009, I continued running but abandoned my diet algother. I started eating whatever I wanted, which included a lot of Domino’s and Ben & Jerry’s ice cream.

But I continued to lose weight — right up until the end of October when I stopped running. It seemed that no matter what I ate, the fat was still dropping off me.

The potential reasons for this are myriad, but one particularly strong argument is that my metabolism had been heavily boosted by the running. In short, I was able to eat more food than I could have before (even with the calories burned through running accounted for) and lose more weight than I otherwise would have.

In other words, my body was changing the way it dealt with the calories that entered my body.

Examples of such outcomes can be found with ease. Consider this: when Ray Cronise, a material scientist at NASA, heard that Phelps consumed 12,000 calories per day, he couldn’t believe his ears. The calories in, calories out theory told him that to do so and not become morbidly obese simply wasn’t possible. The following excerpts are from The Four Hour Body:

In order for Phelps to burn those kinds of calories above and beyond what his resting metabolic rate was…he would have to sustain more than 10 hours of continuous butterfly every day. Not even he can do that.

After a great deal of thought Cronise hit upon a theory: that the thermal load of the water was affecting Phelps’ metabolism.

The effect was the same as pouring hot coffee into a metal cup instead of a ceramic mug; the former loses calories (heat) much faster.

Cronise discovered that while the simple theory of calories in, calories out might technically be correct (in its most literal form), the popular interpretation of the theory is completely wrong.

Why? Because it assumes that calories can only follow two pathways once they enter the body: exercise or storage. The concept of excretion (through heat or waste) is largely ignored.

Mountain climbers lose enormous amounts of weight while scaling the tallest peaks in the world because their body needs far more energy simply to exist. Extreme temperatures can have a drastic effect on how calories are expended by the body (and thus, how much fat is stored).

Alternatively, we could talk about the astonishing number of other factors that can affect your weight, such as the amount of sleep you get, the times at which you eat and the type of exercise that you do.

While these examples aren’t directly relatable to the main argument of this article (that protein, fat and carbohydrates are all treated very differently by the body), they serve to highlight that the calories in, calories out theory is hopelessly flawed. While you can lose weight by simply adopting a calorific deficit, there are far easier (and more enjoyable) ways to lose weight.

What This Means for Being Healthy Enough

It makes logical sense that a diet high in the nutrients that the body needs most would be good for you. But what does this mean for us? Should we all immediately jump on high protein, low carbohydrate diets?

I’ll say this first: do whatever you want. Don’t feel that you have to get sucked into something like the Atkins diet (which, incidentally, is not a diet I would ever recommend). If you replace your daily chocolate bar with a can of tuna then that in itself is an improvement worth of applause (and will result in net weight loss in the long term).

The Healthy Enough way is not to encourage eating regimes that are difficult to sustain. If you take anything away from this article, I want it to be that even the smallest of changes can help you to lose weight in the long run. You don’t even need to reduce your caloric intake or even worry about how many calories you are actually consuming – just eat different things.

With the above in mind, let’s look at a four simple adjustments you can make to what you eat that will enable you to lose weight.

1. Eat a Protein-Rich Breakfast

Replace your cereal, bagel and or toast with bacon and eggs (go for free range or organic if you can afford it to derive the best nutritional value, but don’t sweat it if you can’t).

Seriously — starting the day with bacon and eggs can be good for you. I shit you not. Just try it for a couple of weeks and see if your weight loss increases (or weight gain reduces).

2. Eat Protein-Rich Snacks

I personally like a couple of slices of smoked salmon in the late afternoon (I have a serious smoked salmon obsession). It’s high in protein and essential fats and is delicious to boot. You can try anything you like though — pre-cooked chicken breast, cooked meats (make sure you get the good stuff) and boiled eggs work too.

3. Replace Carbs With Lesser Evils

One of my favorite things to do with curry is first halve the rice and double the amount of chicken, then halve the rice again and add some broccoli and cauliflower to the mix. You’ll still be eating the same mass of food (i.e. your eyes will still see a full plate and tell your brain that you’re not trying to starve yourself), but the carb hit will be much lower.

Alternatively, you can do complete swaps. I really like lentils in place of rice. You can try cauliflower mash in place of potatoes (it’s surprisingly good, especially when you throw in some salt, pepper, butter and mustard). Or spaghetti squash in place of pasta.

4. Swap Your Carbs to Protein Ratio in Your Meals

If you can’t bear to let go of your favorite carbs, try swapping your carbs to protein ratio. Most meals have a high carbs to protein ratio — i.e., you’ll have a load of carbs on your plate and a relatively low portion of protein. Turn that ratio on its head.

This is easy with say spaghetti bolognese — use half the amount of spaghetti and twice the amount of mince. You can do the same with curry (half the amount of rice and twice the amount of chicken). Have twice as much meatloaf and hold the potatoes. You can achieve this with just about any meal and you probably won’t even notice the difference. Even if you do, you probably won’t mind.

What About Candy?

The biggest problem I have with a low carb diet is the lack of chocolate. I love chocolate.

Put simply, it can’t be substituted. While I can cut out potatoes from a meal and not feel like I’ve cheated myself, missing out on chocolate is a pretty big deal for me. Nothing beats it.

So my advice here is simple: if you can make some sustainable changes to your diet but continue to eat chocolate and start losing weight, you’re golden. Remember — if you’re losing weight week by week on a sustainable diet, you will keep losing weight for a long time. You’re running a marathon, not a sprint.

If you’re not losing weight then you will have to consider sacrifices. However, I would still not advise that you cut out candy from your diet in the long term — that’s a relapse waiting to happen. What you can do is cut it out sporadically — for periods of time (say a week) where your willpower will hold out. If you can do this every now and then you may find that you lose weight in the long run.

Alternatively (or additionally), you can try out alternative snacks that are higher in fat and lower in sugar.

Is There Still a Place for Calorie Counting?

Proponents will argue that even if the calories in, calories out theory is imperfect, it can still be used as part of a weight loss program.

I can’t disagree with that — after all, I’ve counted calories to lose weight in the past. However, I have never been on a calorie restricted diet that has satisfied me. Going hungry is not the Healthy Enough way, which is one of the main reasons that I do not recommend calorie-controlled diets.

If you are calorie counting but still consuming a diet that is high in carbohydrates, not only will your weight loss be less efficient than it would on a low carb diet, but you will also find yourself going hungry. This is due to the decreased effect on satiety that is brought about by the consumption of carbohydrates (when compared to protein or fat).

It’s exactly why you can eat a pint of ice cream with little trouble but can’t so easily eat an enormous slab of steak. In layman’s terms, the ingestion of carbohydrates leads to a spike in blood sugar that leads the body to want more of the same. This same reaction does not occur in the body when you consume protein or fat, which both release glucose into the system in a far less impactful manner.

In my opinion, it is far better to cut down your consumption of carbs and carry on eating without concern for calories. If that doesn’t result in weight loss then you should take another look at the amount of carbohydrates you are consuming – it is probably still quite high.

Put simply, if you live off a low carb diet you will almost certainly not gain weight (regardless of how much you eat). Eating enough food to satisfy yourself and keep hunger at bay while maintaining or losing weight is definitely the Healthy Enough way.

Forget Calories

I’d like to wrap things up by formally inviting you to forget about calorie counting. It’s an onerous and ultimately misleading method of weight management.

Instead, think intuitively and practically about what you eat. While I love carbs, the decision to have two breasts of chicken and half the amount of rice with my curry is a no-brainer. I like rice and want it in my meal, but I love chicken and have no problem having less rice for more meat. On a similar note, starting the day off with bacon and eggs is highly satisfying and tends to keep me going all the way through to the lunch.

Understanding the effect of different nutrients on your body can give you pause for thought, which can be enough to discourage you from gorging on carbohydrates. Next time you pick up a chocolate bar, take a moment to realize that your body may convert every last bite into fat and send it off to some unsightly place on your body. Yes, it’s damned tasty (and I’m not going to tell you to put it down), but eating it is not really a natural act. If you feel comfortable with grabbing a chicken drumstick instead, be my guest. Your body will do far more good with it.

In conclusion, the more educated you are on what happens to the food you eat, the more likely you are to eat right. Forget about calories and pay intention instead to what you eat. The rest will follow.

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