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A Calorie is Not a Calorie

May 16, 2009

When we go on a diet we often watch our food intake by ‘counting’ calories.

But new evidence has shown that all calories are not created equal.

3500 calories = one pound…always?

Among nutritionists it is commonly taught that a calorie is a calorie. This is the cornerstone dogma that has established a number of metabolic rate calculations to estimate the proper number of calories for weight loss, weight gain and food labeling.

This means that in order to lose weight all you need to do is decrease your calories by 3500, the number of calories in a pound, and you will lose at least a pound of weight (hopefully fat weight), no matter if they come from fat, protein or carbohydrates; and vice versa for those wanting to gain weight.

Theoretically, calories in = calories out = no increase/decrease in body mass. This is true according to the First Law of Thermodynamics, which states energy is neither created nor destroyed, only transferred as heat.

The Second Law of Thermodynamics says processes always go in the direction of randomness or disorder (entropy). This law suggests that the exchange of energy will be imperfect, such that some energy will escape, as heat, thus increasing entropy in the universe.

In terms of our body, the metabolism of proteins, carbohydrates and fats may be very different depending on our hormonal state and enzymatic activity. Therefore, individual uniqueness should be expected among us as individuals.

Finally, the late Mel Siff, PhD., suggests in his book The Facts and Fallacies of Fitness another problem comes when we look at how scientists accept the number of calories in foods. The calorific values of foods quoted in diet books may not be as accurate as previously thought:

How are Caloric Values Determined?

First, calories are determined by a special chemical process called proximate analysis or by burning quantities of each food in a bomb calorimeter, a type of scientific furnace, which measures the amount of heat produced in each case. Scientists take this information and assume that it creates this same amount of heat in a low temperature combustion inside a person.

It is also assumed that all components of the food are metabolized according to the characteristics of the food. For example, a food with soluble fiber should always be absorbed. However, not all “soluble fibers” always get absorbed into our bodies. It is also assumed that all components of the food are metabolized according to proximate analysis estimations, and that the combustibility of the food does not vary with source and quality (even though the combustibility of coal varies with type and source). Doesn’t seem to make sense, does it? Who started these assumptions? Somebody did not tell the whole story. Let’s keep looking at this.

Influences in Burning Calories

The calorific values of proteins, carbohydrates and fats and their components (such as, amino acids) vary with the foods and mixture which are in it. Protein, by itself, takes approximately 30% more energy to metabolize than fats or carbohydrates. This is one reason why many high-protein dieters are successful with these types of fat loss diets.

Also, food components change their characteristics during the cooking process (such as fiber content increasing after frying starch) or may not be fully digested because of the amount swallowed or because of the interaction of a food’s components (affecting the overall glycemic index of the meal) or digestive enzymes involved. For example, sugar dissolved in water (such as in soft drinks) provides more energy and produces more body fat than sugar eaten in solid form.

Therefore, at the energy production level, there are major inaccuracies of computation.

At the biological “furnace” level, each person’s biochemical individuality determines how efficiently a given food will be digested, stored or used as a fuel for energy. Studies with twins on exactly the same exercise program and diets have shown that the amount of weight loss or gain differs with the individual.

Other studies using various calorie equations for weight loss have resulted in no weight or little weight loss for obese individuals, making it a very frustrating experience. However, there are thousands of successful stories of obese people decreasing body fat by reducing calories and exercising as part of a healthy lifestyle. So, it is not clear, and for some, a diet modification may still have to be further enhanced by personal judgment.

Individual responsibility

It is clear that the science of calorie counting based on food burning computations is scientifically and practically misleading. However, this does not mean that you can eat whatever you want and still expect to lose weight, or that you should hold the “I’m a victim”-attitude and give up.

You still do have an answer to achieve fat loss or muscle mass gain. Although those equations are ESTIMATIONS, based on a large population, not you the individual, the First and Second Laws of Thermodynamics still apply – they are laws, not theories or hypotheses. Therefore, the concept of calories still applies and cannot be ignored. You still need to keep an open mind because the “calorie situation” is not as clear as once thought, but it is the best science has to offer.


This entry was posted in Nutrition.

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