(1) The flaws in counting calories (2) Counting calories
(1) The flaws in counting calories
In August 2003, Barry Groves made the following
contribution to the
Paleodiet discussion list:
High-fat diets have a scientific basis - if we think it through - That high-energy diets work better for weight loss has often been puzzling, and it has proved very difficult for dietitians and doctors to accept them because, on the face of it, they appear to challenge the laws of physics. But there are several reasons why they do not.
All carbohydrate -- sugars and starches -- contains energy to the value of four calories per gram and fat has nine calories per gram.
How scientists determine the calorific content of foods - The calorie is a unit of heat. The way the energy content of a food is determined is by burning it in a device called a 'bomb calorimeter' and measuring the amount of heat it gives off.
If we take a gram of carbohydrate and burn it in this way, we get an energy value of 4.2 calories, or more correctly kilocalories (kcals). If we do the same with protein, we get a figure of 5.25 kcals. But we must deduct one calorie because we know that a gram of protein does not oxidise readily and gives rise to urea and other products to this value which are excreted and which must be subtracted. That gives a final figure for protein of 4.25 kcals. And if we burn a gram of fat in the bomb calorimeter we get 9.2 kcals.
These figures are then rounded to the nearest whole numbers: 4, 4 and 9 respectively, and are reported in calorie charts to indicate the energy values of foodstuffs and, thus, to allow slimmers to measure the amounts that they may eat. But there are two basic flaws in using these reported calorie figures to determine the amounts of food we should eat.
The first flaw about eating according to reported calories - The more obvious flaw in the argument is that our bodies do not burn these foods in the same way that they are burned in a bomb calorimeter. If they did, we would glow in the dark. In fact the digestive process is quite inefficient so that all we eat is not even absorbed by the body, let alone used by it. The chemical process, whereby the blood sugar, glucose, is oxidised in the body to provide energy, gives rise to carbon dioxide that leaves the body via the lungs as we breathe. Clinicians measure energy use by getting their subjects to exercise on a treadmill or an exercise bike and measuring the amount of oxygen breathed in and the amount of carbon dioxide breathed out. But if you are going to equate energy intake with energy expenditure, you can only do it if all the carbon leaves the body in this way. But it doesn't. In fact, only about half is exhaled as carbon dioxide, the other half is excreted in sweat, urine and faeces as energy-containing molecules: urea, lactates and pyruvates, the energy values of which must be deducted from the original food intake. All of these can vary from time to time and they also vary with the types of food eaten. We know, for example, that if a lot of fat is eaten, it puts ketones into the urine. And we know that the value of a gram of ketones derived from fat is roughly four calories. So, in this case, nearly half the energy from fat goes, not into providing the body with energy, but down the toilet. 
The second flaw about eating according to reported calories - Nutritionists frequently liken eating food to putting petrol in a car -- simply treating food as fuel. But this concept is quite wrong. Unlike the car, your body has the ability to repair and renew itself, for which it uses proteins, fats and other nutrients found in food. The second and more important flaw in the argument, therefore, is that your body does not use all the food it has available merely to provide energy.
Dietary carbohydrates - All edible carbohydrates have but one purpose: to supply calories that your body can use for energy. Counting them might have some point, as they do nothing else. But while the body can use proteins and fats to provide energy, they do very much more -- in ways that do not involve the production of energy.
Dietary protein - Body cells are constantly growing, wearing out and being replaced. No matter how many birthdays you have had, very little of you is more than eight years old. Dietary proteins are primarily used in this process: for the manufacture and repair of skin, blood and other body cells; to make hair and finger- and toe-nails. The amount of protein needed for this purpose is generally accepted to be about one gram per kilogram of lean body weight. As meats contain approximately 23 grams of protein per 100 grams, a person weighing, say, 70 kg (11 stones) needs to eat about 300 g (11 oz) of meat, or its equivalent, every day just to supply their basic protein needs. These calories are not used to supply energy; they contribute nothing to the body's calorie needs and so must be deducted if you are counting calories.
Dietary fat - Much of the fat we eat is also used to provide materials used by the body in processes other than the production of energy: the manufacture of bile acids and hormones, the essential fatty acids for the brain and nervous system, and so on. All these must be deducted as well.
Conclusion: don't count calories! - Thus trying to determine, from food intake and energy expenditure, how much excess energy your body will store as fat will give a completely wrong answer unless these other factors are known and allowed for. But how do you measure these? The simple answer is: you can't. There is no point, therefore, in trying. And calorie counting, which is the foundation of practically every modern slimming diet is a waste of time.
Much of what we eat today is not natural to us as a species. A proportion of this will pass undigested through the gut. Even herbivores waste around half of their intake through imperfect digestion and absorption. As we are not herbivores, it would not be unreasonable to assume that our gut is at least as inefficient at processing such material, particularly if it is eaten in the raw state.
evidence for our being carnivores is contained within us: our gastrointestinal
tract. As biochemistry textbooks are not the easiest books to read, see Walter
Voegtlin's book, The Stone Age Diet, published in 1976, for a masterful
treatise on the subject.
Barry kindly gave me permission to reproduce the above article and invites you to visit his website www.second-opinions.co.uk
(2) Counting calories
"Should I count the calories of the foods I eat in order to keep my dietary intake within limits?"
This question is one of the most frequently asked. The usual answer by those who are best-informed on diet from the perspective of our Palaeolithic past in a Plestocene world is "No - there is no need. And it is a distraction from the fact that what you eat is a better moderator of dietary excess than keeping a tally".
Some people like to keep track of their lives, keep a diary, plan their day and enjoy the comfort of being organized. I would not discourage them from keeping a record of their calorie intake.
Others prefer spontaneity, trusting to their feelings and deplore fastidiousness, neatness and order. There is little point in these people fighting their character to record their intakes.
As Loren Cordain's The Paleo Diet makes clear, what you eat is far more important than precisely how many calories you consume. Rob Faigin's Natural Hormonal Enhancement shows that when you eat as well as what you eat is also significant.
In my experience, calorie counting is a sign of the beginnings of an understanding of human nutrition. It is a stage many people pass through as they become aware of the complexities of diet and their health. No harm in passing through that stage, even if it takes a few years.
1. That is, the advocates of counting "calories in", as well as ignoring the fact that some protein calories are required for bodily maintenance, also assume that faeces and other bodily discharges, including exhalations, are totally calorie free.
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