Most of us know in our heads that not all calories are equal.
A bar of chocolate and an apple may contain similar numbers of ‘calories’, but we know the apple is clearly better for us and the bar of chocolate ‘less good’.
But after a lifetime of hearing about the calorie and its role in diet advice we could be forgiven for being confused about how best to eat to gain weight, lose weight, or maintain weight. After all many weight loss experts in the world constantly use the term.
It’s time to lay the calorie confusion to rest and to ignore (or even blame) those that perpetuate the lie.
Using the 'Calorie' as a unit of energy in relation to weight is so misleading as to be absolutely meaningless.
The reason why some people still hold onto using this ‘measure’ is that they believe in a general principle that fat storage is simply a question of equalising calories in versus calories out, aka CICO (pronounced psycho). This is the ‘energy balance’ theory: More calories out than calories in = fat loss. More calories in than out = weight gain.
But that theory is inherently wrong and unscientific.
If used because the concept of ‘calories’ linked to weight is misunderstood (usually as the result of outdated academic textbooks or personal training conventional wisdom), then the user is unwillingly incorrect and requires re-educating.
If used to protect a methodology that traps people into the 'energy balance' vicious cycle of more exercise, creating a faster metabolism, creating more hunger, creating less compliance to energy needs, more hunger, not losing weight and creating more exercise, then it's a business model that is deceptive and abusive.
Those that promote the idea of a 'calorie deficit' claim a calorie deficit cuts fat but ignore the fact a calorie deficit can also cut muscle and bone density, slows down metabolism, and can make us insatiable hungry. That's because our bodies don't crave calories. they crave nutrients.
The commonly held belief of CICOpaths is that to lose 1lb (453grams) of fat you need to create a deficit of 3500 calories. But there is no scientific evidence to prove this, and it doesn’t make any sense.
453g of fat doesn’t equal 3500kcal (it’s 4077kcal). Even if it did that would mean that by cutting calories by 500kcal per day you could lose 91 kgs in 6 months, what if you only weigh 80Kgs?
The value of food is not simply a fuel to be burned or stored, it is much more complicated than that. The ability to lose weight (or gain it) depends on the kind of food you eat, when you eat it, your health status, your genes, your environment, and much more.
History of the 'Calorie'
The word is derived from the Greek word for heat, 'calor'.
Antoine Lavoisier, a French aristocrat in the late 1700s, built a 'calorimeter'. The device measured the heat a small animal generated to 'estimate' how much energy it was producing. Later scientists constructed “bomb calorimeters” in which they burned food to measure the heat released from it.
'Heat, energy, and food', but no mention of fat.
The idea of ‘calories in - calories out’ is more than 100 years old. Wilbur Atwater, an American scientist in the late 1800s, started the idea about calories that is now the conventional wisdom of today. He believed that “a calorie is a calorie”. By his theory, it made no difference whether calories came from chocolate or spinach: if you ate more calories than you used, then you would store the excess as body fat.
Lulu Hunt Peters, in her book “Diet and Health” in 1918, promoted the notion that a healthy diet was no more complicated than the simple addition and subtraction of calories. She made up the mathematics of weight gain from her imagination. “You may eat just what you like – candy, pie, cake, fat, meat, butter, cream but count your calories!” Of course, the book sold millions.
In it she claimed ‘500 calories equal approx. 2 ounces of fat. Two ounces per day would be 4 ounces per month or 48 lbs per year. Cutting 1000 Calories per day would equal a reduction of approx. 8llbs per month or 96llbs per year!' Followed by 'The words are clever I wrote them myself!'
Calories mythology today
The World Health Organisation (WHO) -that are sponsored by the big food companies -attribute the cause of obesity worldwide to an energy imbalance between calories consumed and calories expended (Big Food's deceptive trick). So, governments around the world offer the same advice to count calories and label food accordingly.
The WHO also admits that the concept is so cemented in consumer behaviour, public policy and industry standards that it would be too expensive and disruptive to make big changes.
In America regulations allow food labels to understate calories by up to 20%. The information on some frozen foods understates their calorific content by as much as 70%.
It is widely known that the calorie system is unscientific and unhelpful. The UN’s Food and Agriculture Organisation (FAO) announced that Wilbur Atwater 19th century calorie-counting system is “a gross oversimplification”. So inaccurate that they mislead people into selecting unhealthy products because they understate the calories. Almost 20 years ago the FAO said it would consider redefining the system, but still has not.
The FAO even rejected the idea of standardising the methods used in different countries – a label in America can give a different count from one in Australia for the same product with the same exact ingredients.
The experiments that Atwater conducted a century ago, on an abacus probably, have never been repeated even though our understanding of how our bodies work is vastly improved.
How do humans absorb and store energy?
Calories attributed to food are based on how much heat a foodstuff gives off when it burns in a calorimeter, but the human body is far more complex than an oven.
It is not the closed system of an oven that the First Law of Thermodynamics (also known as Law of Conservation of Energy, states that ‘the total energy of an isolated system is constant; energy can only be transferred or changed from one form to another’) requires, and the one often quoted by calorie deficit proponents.
Look, if you accept that water has zero Calories, but a very cold glass of water has a negative thermic (energy loss) effect then you can see why the First Law does not apply.
In fact, the clothes you wear, the chair you’re sat on, how hydrated you are, your genes, microbiome, inflammatory and hormonal status are just a few of the other systems at play that trump thermodynamics.
Furthermore, when food is burned in a calorimeter it gives up its calories within seconds. But the real-life journey from dinner plate to toilet bowl takes on average about a day, so time is also a function.
In theory, one gram of carbohydrate and one gram of protein both have the same amount of 'stored energy' (4kcal). But put those nutrients into a human and they behave very differently (See Thermic effect below).
The process of storing or losing fat is influenced by dozens of factors. Apart from the nutrients, and other internal or external systems in play, food preparation, and sleep also affect how we burn or store food.
For example, all carbohydrates break down into sugars, like glucose and fructose. But the speed at which your body absorbs this energy from food can be as important as the amount of energy consumed.
Refined carbohydrates are quickly absorbed into the bloodstream, providing a fast shot of glucose energy.
The body absorbs the sugar from a can of fizzy drink at a rate of 30 calories (7.5g or about 2 teaspoons) a minute, compared with two calories a minute from complex carbohydrates such as potatoes or rice (0.5g per minute).
The total amount of glucose in an adult blood volume is about 4 grams. This is important, as a quick hit of glucose creates the rapid and relevant release of the hormone insulin from the pancreas.
Hyperglycaemia (more than 4g) is the dangerous potentially deadly situation that occurs when there is too much glucose in the blood. So the body has a mechanism for dealing with any excess glucose. Insulin signals cells to pull the glucose out of the bloodstream and store it.
Firstly, the liver and muscles can store some of the excess glucose as glycogen. The muscles and liver can store about 650g in an adult.
Once they are full, more excess glucose is converted into triglycerides in the liver and stored in fat cells.
So eating either hyper-absorbable glucose and/or large quantities is the quickest way to create body fat.
Once the insulin has done its work, and glucose is stored then blood-sugar levels can slump. This tends to leave people hungry and programmed to eat more glucose loaded food.
Everyone has experienced that lightheaded, anxiety-inducing hypoglycaemic attack and quickly grabbed a chocolate bar or orange juice to ‘take the edge off’.
Being able to store energy as fat is a consequence of evolution. Our palaeolithic ancestors would only have had access to any glucose or fructose perhaps once a year when fruit ripened in late summer. Fat stores built at that time would allow us to see through winter.
But the average person in the developed world consumes 20 times as much sugar as people did even during Atwater’s time and 700 times as much as we did 50,000 years ago.
In the USA, adults consume on average 70kgs of sugar and 70Kg of refined carbs (wheat flour, etc) per year. It is calculated that ‘we’ only ate around 200g of carbs per year before the agricultural revolution 13,000 years ago.
Other essential macronutrients have different functions in the body
Fat is a very slow-burning energy source, In the absence of carbohydrates/glucose, we convert fat to ketones to feed our energy requirement.
We also need fat to make hormones, to make new cell membranes and to protect our nerves.
Throughout history, fat has been a crucial way for humans to find energy. Because gram for gram it is more energy-dense than carbs and it is a great way to store energy, allowing us to survive periods of famine.
Our genes are programmed to store excess fuel in case we run out of food.
Protein, once broken down into amino acids, acts as the building component for all cells: muscle, bone, skin, hair, and other body tissues.
In the absence of carbohydrates, protein can also serve as a fuel for those cells in the body that can only use glucose (red blood cells and some brain cells).
The liver can make protein into glucose through a process called 'gluconeogenesis' to supply those cells when and if it is required to. All other cells can use ketone bodies for energy. Ketones produce less Reactive Oxygen Species (Free Radicals) when converted to usable energy.
Protein also raises insulin a lot lot less than carbohydrates and is digested much more slowly.
Therefore protein is unlikely to be converted to body fat.
Calories are not absorbed equally
Some people’s intestines are 50% shorter than others. So, those with shorter guts excrete more of the energy in food, absorb fewer calories.
Processing food does part of the work of digestion. Chopping, grinding, fermenting, cooking all make more energy available to your body. Cooking alone can double the energy made available in the amount of food digested.
The energy potential of rice, pasta, bread and potatoes can be slashed simply by cooking, chilling, and reheating them. As starch molecules cool they form new structures that are harder to digest. You absorb less energy eating toast that has been left to go cold, or leftover spaghetti, than if they were freshly made.
The hormonal theory of obesity
Sugar and highly processed carbohydrates play havoc with people’s hormonal systems.
Higher insulin levels mean excess energy can be pushed into fat tissues leaving less available to fuel the rest of the body. That in turn drives hunger and overeating.
The constant hunger and tiredness suffered by dieters may be symptoms of being overweight, rather than the cause of the problem.
Yet much of the food industry defends the status quo too. To change how we assess the energy and health values of food would undermine the business model of many companies.
While insulin is present (from constant grazing), it's sister hormone glucagon (responsible for signaling to fat cells to dispose of the stored fat) is suppressed.
Simply put, lipolysis (fat loss) requires you to be in ketosis. Not 'calorie deficit'.
Thermic Effect of food
Converting food into energy requires energy. Depending on the nutritional profile of the food 'costs' in terms of chewing, digesting, absorbing and maintaining acidity and temperature regulation, amongst other things.
Digesting protein transfers only 70 - 80% of the energy it contains, carbohydrates 90 - 95%, and fat is the most 'efficient at 97 - 100%.
For example :
- 100kcal of protein consumed only 75kcal is available
- 100kcal of carb only 92.5kcal is available
- 100kcal of fat only 98.5kcal available
Two items of food with identical calorific values may be digested in very different ways.
Each body processes calories differently.
Even for a single individual, the time of day that you eat matters. The more we probe, the more we realise that tallying calories will do little to help us control our weight or even maintain a healthy diet: the beguiling simplicity of counting calories in and calories out is dangerously flawed.
Basal Metabolic Rate
Basal metabolic rate (BMR) is defined as 'the rate of energy expenditure per unit time in a physically and psychologically undisturbed state, in a thermally neutral environment, while in the post-absorptive state' (i.e., not actively digesting food).
Metabolism comprises the processes that the body needs to function. Basal metabolic rate is the amount of energy per unit of time that a person needs to keep the body functioning at rest.
Some of those processes are breathing, blood circulation, controlling body temperature, cell growth, brain and nerve function, and contraction of muscles.
The human body uses the energy released by respiration for a wide range of purposes: about 20% of the energy is used for brain metabolism, and much of the rest is used for the basal metabolic requirements of other organs and tissues.
In cold environments, metabolism may increase simply to produce heat to maintain body temperature. Among the diverse uses for energy, one is the production of mechanical energy by skeletal muscle to maintain posture and produce motion.
The basal metabolic rate accounts for about 60 to 75% of the daily energy expenditure by individuals and is influenced by several factors, not least of which is the energy available to use.
Physical Activity Level
This is the element that most PT focus on.
They'll suggest that the exercise will 'burn calories'.
For example, a 60-kilo woman walking for 30 minutes might ‘burn’ 125 calories
But what would you burn if you were just sat on the sofa watching TV (BMR), because it's the net that's used, not the total.
If your BMR is quite high because you are eating energy-rich foods you might 'burn' 80 kCal per hour, so would've used 40 kCal in that 30 minutes anyway.
So the net effect is 125 – 40 = 85 kcal. Or approx. one TimTam or half a can of coke.
Two beers might equal 225 kcal, the net over an hour 100kcal. To burn 125kcal requires that 30 minutes walk again.
The Calor[L]ie
Next time you here the calor[l]ie remember, humans are not internal combustion engines. We are complex open systems that store and unstore fat according to our evolutionary biology, not a law of physics, nor mathematics.