The secret to reading nutrition information panels – part 3: lab report – calories – and why they DO matter!

Is there really any sense in counting calories?

In the last two parts (part 1 and part 2) of this series we learned how a nutrition panel is built up, what the difference is between a Big 4, Big 7 and Big 8 label and how to determine the fat content of foodstuffs in a laboratory.

Table 1: Nutrition facts of Dr. Almond ’Our Mild Bread’ (finished bread)

In this process, the fat is carefully isolated from the food and weighed afterwards. The value then shown in the nutrition panel is determined by direct analysis. The analysis method used is listed in the table right to the respective value (see table 1).

However, there are values that are inappropriate for a specific analysis method: these values will then be calculated. This includes net carbohydrates in general, sodium chloride and the energy value – that is to say the calories.

In this article, we are going to take a closer look at the calories.

Actually, the term energy value is not quite correct and leads very often to confusion.

You have to exactly distinguish between the thermodynamic and the physiological energy value.

The thermodynamic energy value in general corresponds to the energy content of a substance (whether or not it’s a food item), which is released on complete combustion. This energy can be measured with a bomb calorimeter, however, this value has little meaning for the energy our body can really draw from it. A coal briquet e.g. has a very high energy value – nevertheless, human beings wouldn’t gain any energy from it if they allowed themselves a piece of coal briquet with dinner.

Therefore, research was early engaged in determining the physiological energy value of usable macronutrients (carbs, protein and fat).

Wilbur Atwater: The physiological energy value

As early as the 19th century (around 1875), researchers examined macronutrients as source of food energy for humans and animals. In 1899, this resulted in a scientific paper by Wilbur Olin Atwater (1844 – 1907) stating that carbohydrates and proteins are metabolized in the human body to approx. 4 kcal per gram and fat to approx. 9 kcal per gram. This calculation takes into account that our body is not 100% efficient at converting food into energy – one portion of it e.g. leaves the body as excrement. Furthermore, various correction factors had been applied based on specific tests on humans.[1]

In that respect, the physiological energy value in general differs from the thermodynamic energy value in the sense that the physiological energy value is much lower.

Accuracy and significance of the energy value in foodstuffs have often been in the crossfire of public debate.

Regarding the time of first publication of Atwater’s paper [1] at the end of the 19th century, we might safely assume that those values are obsolete.

Far from it: nearly 100 years later, a British research team (Southgate & Durnin 1970) took up the challenge to review and recalculate all values given and obtained almost identical results. The only new discovery was the differentiation of usable (net) and non-usable carbs (dietary fiber). They found out that the volume of excrement per person significantly increased with a higher intake of dietary fiber (that means the test persons metabolized less) and found the value given by Atwater of 4 kcal per gram to be quite too high for some carbohydrates. [2]

Later research provided even more exact results and researchers then calculated a physiological energy factor for dietary fiber of 2 kcal / gram. [3]

The result of more than 100 years of intensive research work is represented in the following values in table 2:

Table 2: Physiological energy value of macronutrients

macronutrient physiological energy value in kcal/g

 

fat 9
protein 4
carbohydrates (net) 4
dietary fiber 2

These values remain the same today and are still used for calculation of the energy value of foodstuffs. The amount of fat, protein, carbs and dietary fiber defined by analyses is multiplied by the values from the table and comes to the total of energy value, which is finally shown at the top of a nutritional table.

By differentiating dietary fiber from carbs, however, you’ll get different accuracies in different nutrition information panels. In table 3, we calculated the energy value of our Mild Bread using the analysis values for macronutrients. The Big 7 chart fails to take account of dietary fibers (they are added to the total carb amount) and this is why the values differ considerably from the results shown in the Big 8 chart. You’ll always get more accurate values in a Big 8 chart.

Table 3: Calculation of the energy value (kcal) in Dr. Almond Our Mild Bread (Big 7 compared with Big 8)

Big 7 Big 8
Protein (4 kcal per gram) 14,1 x 4 = 56,4 14,1 x 4 = 56,4
Carbs (4 kcal per gram) 16,4 x 4 = 65,6 2,6 x 4 = 10,4
Fat (9 kcal per gram) 2,8 x 9 = 25,2 2,8 x 9 = 25,2
Dietary fiber (2 kcal per gram) 13,8 x 2= 27,6
Kcal per 100 g 147,2 119,6

But how accurate is the calorie content anyway?

This question is frequently asked and well justified.

Analysis methods always involve a certain degree of inaccuracy and, in addition, not every metabolism works in the same way.

Yet, we should not badmouth these values too much!

After all, research has been dealing with optimized analysis methods for quite a long time so that we can assume a comparatively low deviation when analyzing the absolute values of macronutrients. When doing nutrition labeling for foodstuffs, tolerances of +/- 15% are accepted for macronutrients, what seems to be very high at first glance. But if you take a closer look at one specific value (e.g. Our Mild Bread (table 1), with a protein content of 14.1g per 100g), 15% more yields a value of 16.2 g  and 15% less yields a value of 12.0g – this is a difference of 2g plus or minus. If we look at the values for carbs and fat, we are talking about a deviation down to the milligram range –  in our example this would be a difference of 0.42g for fat and 0.39g for carbs!

The fact that this food is rich in protein and very low in carbs, is not questioned at all  by this deviation. Furthermore, don’t forget that there are both upward and downward deviations – for each individual nutrient. As we have just learned, the energy value of a food item is calculated from the individual values of macronutrients contained in it, and not by one single measurement done in a bomb calorimeter.  It is highly unlikely that the deviation in all macronutrients points in the same direction (e.g. towards ’too high’). A deviation of more than two grams in protein and less than one gram in fat still adds up to a reasonably accurate energy value for the food item as a whole. That means, deviations partly balance each other out.

With the help of a nutrition facts label, the intake of energy and macronutrients can be easily calculated per person. However, any calculation with digits behind the decimal point is pretty useless, much rather, it must be seen merely as a rough guide in order to maintain overview of your daily intake.

The problems arise when you try to correlate the values for nutrient intake with specific values for the body’s energy requirement or energy expenditure to be generally valid for everyone.

There are indeed complicated formulas to calculate a person’s basal metabolism or physical activity level depending on its size, weight, muscle mass and activity, which would cough up a value of e.g. 2,000 kcal for a woman who is 1.70 m tall. Those formulas, however, are subject to high error ratios and should, in theory, be specified separately in a lab for each person and each daily routine (activity and recovery phases). Since this kind of analysis will probably never be an option for most of us, the question arises to what extent I will be able to benefit from my knowledge about nutritional values and the energy value of foodstuffs.

Quite simple: it’s just a rough guide whose correlation with your own energy requirement needs to be discovered by yourself individually. Those who wish to shed weight and have to discover that, after some weeks, the scale won’t budge with a daily intake of 2,500 kcal, you might try to cut down to 2,000 kcal. As soon as you note a steady weight loss, you’re doing good.

BUT TAKE CARE: this system works only in combination with a low-carb diet!

On a high carb diet, a huge amount of insulin has the effect that parts of the absorbed calories cannot be converted into energy but are directly stored in the body as fat. The result: Our cells don’t get enough energy despite a sufficient food intake, as you might think, and you feel hungry again shortly after eating. But another intake of food in the form of carbohydrates will not make it any better and – what is even worse – more fat is stored. If you’re good and count your calories and limit your daily intake to a certain maximum value, you are firstly always hungry and, secondly, you either won’t lose weight or, even worse, gain weight, although you’ve exactly calculated your daily calorie deficit before.

Anyway, it is exactly this vicious circle of frustration that is generally referred to when we hear talk about counting calories makes no sense at all. However, this is only true if you don’t follow a sensible and appropriate diet.

With his masterpiece “Why we get fat and what to do about it“ [4], Gary Taubes has impressively proven that you’re not overweight BECAUSE you eat too much, but that you eat too much BECAUSE you’re overweight . Looks a bit weird at first glance and sounds like splitting hairs. Of course,  an excessive intake of calories will finally lead to overweight. However, this is not a cause and effect relationship. Gary Taubes comes up with a funny analogy to explain it:

Let’s say, you’re sitting in an overcrowded lecture room and you’re asking yourself ’Why is the room so packed?’, and you would, if you applied the same logic as for the calories, get the following answer: ‘The room is so overcrowded because there came in more people than left’. Although this answer is correct, it does not conclude anything about the situation, except that it’s been put in other terms. A real explanation could be for example ’This room is so overcrowded because the organizers booked a room that is far too small to accommodate the huge amount of visitors.’ In the case of calories, the proper explanation would be: We’ll get overweight because we eat the wrong food and, moreover, an overload of carbohydrates attacks our metabolism. This way, we become resistant to insulin (or even develop type 2 diabetes) and always feel hungry despite a sufficient food intake, since our body quickly stores the calories consumed as fat pads rather than making them available to our cells for energy gain. The more overweight we are, the more we show insulin-resistant patterns, ergo: we eat too much BECAUSE we are overweight.

Is calorie counting really useless?

Not at all!!

But: If you adhere to appropriate nutrition that contains few carbs, enough protein and many good fats, you may be fortunate enough to do without annoying calorie counting. In the best of cases, the feeling of satiety as a natural signal should ensure that you don’t eat more than your body really needs, and, in case of heavy overweight, you will even be able to unconsciously maintain a set caloric deficit without starving yourself. Here, the caloric deficit is covered by fat pads that are burnt off your body and you feel perfectly good and satisfied. This is one of the big advantages of a low-carb and LCHF diet.

Unfortunately, this does not work for everyone equally well!

Lifelong obesity, a carbohydrate-rich diet and even low-fat and extremely low calorie diets can ’block’ the natural sense of satiety. Here, trying to check your macronutrient intake and, YES, ALSO YOUR CALORIE INTAKE! could be the only way to success.

Steven Phinney, who authored THE fundamental text book [5] on low-carb nutrition together with Jeff Volek, puts it in a nutshell [6]:

“Don’t count calories, although we ask you to use common sense. In the past, some individuals made the mistake of thinking they could stuff themselves with protein and fat and still lose weight. If the pounds are falling off, forget about calories. But if the scale won’t budge or it seems to be taking you forever to lose, you might want to do a reality check, caloriewise.“

Moreover, people who are just slightly overweight and are very close to their ideal weight, show a balance between their actual energy requirement for an isocaloric diet (that means a diet where you neither gain nor lose weight) and the caloric deficit needed to lose weight that is within a range where they won’t achieve their goal simply by listening to their natural sense of satiety alone. Then it may be helpful for them to get a good overview of their daily macronutrient intake and to manage their overall calorie intake.

The easiest way to do a sort of calorie and macronutrient tracking is to simply use smartphone apps such as Fatsecret or Lifesum, where most food products are already stored in huge databases and all you need to do is entering the quantity of food eaten. In this way, you will be able to keep an eye on your daily intake very easily and, if needed, to adjust your eating habits accordingly.

And again: any deviations in nutritional values are less than ideal, but this should, however, not tempt us to knock the overall concept on the head!

Even if the data are not 100% accurate, you can calculate with them, adapt your diet accordingly and correct and adjust possible differences to your individual requirements.

But not counting calories because it’s not an absolutely perfect system and, instead, getting annoyed about not losing weight despite a strict low-carb or LCHF diet, isn’t a good solution either.

Is a calorie a calorie?

We have heard time and again that ’a calorie is not just a calorie’. Well – the calorie is a physical unit and of course, a calorie is a calorie. That much we know. The meaning of this why-question is rather the health effect of each individual energy-supplying macronutrient. Both protein and carbs carry about 4 kcal per gram. But apart from energy (which is obviously identical), protein and carbs provide some more: a natural cue for your body. When eating carbohydrates, your body releases a considerable amount of insulin (see vicious circle above), whereas a protein intake stimulates certain build-up and repair processes in your body. So we can certainly say that calories in different macronutrients have different effects in the body.

For that reason it is absolutely vital that, apart from the total amount of calories, you also keep an eye on the ratio of the macronutrients fat, protein and carbs in your diet.

We are now familiar with the basics of food analysis and the analysis of fat and energy (calories).

Carbohydrates are the type of macronutrients that have become a focus of special attention by people following a low-carb and LCHF diet.

How is the calorie content of food determined, how do carbohydrates differ from each other and what role does dietary fiber play?

Learn more in the next part of this series

[1] Nichols, B.L., The Journal of Nutrition 1994, Vol. 124, no. 9, 1718S – 1727S
[2] Southgate, D.A.T, Durnin, J.A.G.A, Britisch Journal of Nutrition, 1970, 24, 517
[3] Kritchevsky, D., Bonfield, C.T., Anderson, J., Dietary Fiber: Chemistry, Physiology, and Health Effects, Plenum Press 1990, New York
[4] Taubes, G., Why We Get Fat: And What to Do About it, First Anchestor Books Edition 2011
[5] Volek, J.S., Phinney, S.D., The Art and Science of Low Carbohydrate Living: An Expert Guide to Making the Life-Saving Benefits of Carbohydrate Restriction Sustainable and Enjoyable, Beyond Obesity LLC 2011
[6] Westman, E.C., Volek, J.S., Phinney, S.D., New Atkins For a New You: The Ultimate Diet for Shedding Weight and Feeling Great, Random House 2010

 

One thought on “The secret to reading nutrition information panels – part 3: lab report – calories – and why they DO matter!

  1. Pingback: The secret to reading nutrition information panels – part 5: how to use the right knowledge for weight loss - Dr. Almond International

Leave a Reply

Your email address will not be published. Required fields are marked *

*

Für Bestellungen aus Deutschland und Österreich besuche bitte unseren deutschen Shop!. Dismiss