The modern system for measuring the caloric value of foods was pioneered by Wilbur Olin Atwater, a professor of chemistry at Wesleyan University from 1873 to 1904. Along with colleagues he constructed the Atwater-Rosa calorimeter and through a series of experiments conducted mostly on students, laid the foundation for the modern system used to assign caloric values to foods today. The research of Atwater and his colleagues set the stage for over a hundred years worth of study on the calorie and perhaps most famously, its connection to body weight and dieting.
Anyone who has ever wanted to lose a few pounds or been interested in going on a diet has likely read that the fundamental concept underpinning any diet is the idea of calories in vs. calories out. That is – if you expend more energy than you take in, you will lose weight. Many nutritionists have gone back to this simplistic idea as a reaction to the proliferation of diets which do away with calorie counting but restrict the kinds of foods one can eat, like Atkins. On diets like this, many people yo-yo or do not stay on for the duration purely because they are too difficult to follow. The idea behind following the calories in vs. calories out model is that rather than monitoring what kinds of foods you eat, you monitor their caloric value while allowing yourself to consume the foods you like and can’t give up. In theory, if you have a daily limit of 2,000 calories, it shouldn’t matter if you eat donuts or lettuce, your weight loss should be the same. But is this true? Of course not!
Calories are Complicated…Very Complicated
All calories are not created equally. All foods are not created equally. All bodies are not created equally. Rob Dunn points out in Scientific American that the system we use today to assign calorie values to foods is based on a system of averages – but no food is average! If a medium sweet potato is supposed to have x calories and you pull two medium sweet potatoes out of a bag and analyze them, one will of course have more calories and a slightly different nutritional make up than the other.
What about cooked food? You may have heard that certain green vegetables like kale, are more easily digested and assimilated when steamed rather than consumed raw. This is because cooking certain plants helps to break down the cell wall allowing the body to access more of the calories inside. Even more interestingly, a study by Janet Novotny at the USDA found that because of the difficulty in digesting almonds, for example, the “average” person may actually take in less calories per serving than the nutritional values on the packet would suggest. This could be in part to tougher cell walls but also because the energy our bodies expend to digest food varies according to the type of food. For example, it is commonly known that protein requires more heat-energy to digest, but crucially – as Dunn points out – the loss of calories as heat energy is not accounted for at all on packaging!
To complicate matters further, foods are digested in different portions of the gut depending on the type and how easily assimilated it is. Fruit is digested very quickly where as complex, slow-burning carbohydrates travel further through the digestive system.
Perhaps most importantly to people looking to lose weight – the more processed a food is, the more accurately it reflects the amount of calories on the packaging. Sadie B. Barr and Jonathan C. Wright created a study in which individuals were given meals composed of the same caloric values. One meal was made up of processed food and the other of unprocessed food. Those eating unprocessed food actually received 10% less calories because they spent more of their calories during digestion. The processed food was altered to such an extent that it required very little energy to digest and as a result was incredibly efficient in terms of delivering calories to the body. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2897733/).
For a look at how different foods can affect your body, just look at this YouTube video: https://www.youtube.com/watch?v=M957dACQyfU.
So Should Anyone Count Calories?
For the average dieter, counting calories should not be the focus of any plan to lose weight. Just counting calories is not effective because different foods affect the body in different ways. A 200 calorie soda filled with High-Fructose Corn Syrup will have a different effect on blood sugar and insulin response than would a 200 calorie cold-pressed green vegetable juice. Refined carbohydrates like white flour are major roadblocks to weight loss whereas plant based carbohydrates are not. It is most important to look at the source of calories than the number on the packaging.
As mentioned in previous articles, the key to successful weight loss is eliminating refined carbohydrate intake and monitoring your complex carb intake to ensure it is in line with your average daily energy expenditure. Remember – you should eat carbs when you deserve them! Your meal should be comprised of 60% above ground vegetables, 30% protein, and 10% fats. Some good protein sources include: raw organic and pasture raised eggs, grass-fed beef, grass-fed dairy products (if you your body type allows you to effectively digest them), and wild-caught fish.
At the end of the day, only a small group of people should be concerned with counting calories as part of their nutrition program. Those people are athletes with a specific goal, and those at risk of a deficiency because of chronic under-eating. Counting calories in these instances does not necessarily mean reducing them. In the case of athletes training for an event, the awareness of specific caloric intake can allow for tweaks in diet which could lead to increased performance. For those who chronically under-eat, it may allow the individual to see that the numbers don’t actually add up to what they believe they are consuming.
Quite simply, calories are a guideline. The numbers on the packages are estimates. Remember, all calories are not created equally, all foods are not created equally and all bodies are not created equally. Once you realize this, you are well on your way to using calories the way they should be used, as simply one tool to help you achieve your desired physical goals – not the central focus of your diet!