What are calories?

What are calories?

Defining the concept of a calorie is simple. According to most science textbooks, is the energy required to raise one gram water by one degree Celsius. How does this apply on the caloriecounts that we see everywhere from menus for fast food to snack bar nutrition labels

When we look at caloriecounts, we're usually trying to determine the amount of energy we're pumping into the body. However, a label on a food item will never provide this, at the very least, in a precise manner. There are too many elements that are at play, many of which depend on an individual's physiology, and others that we're still in the process of determining.

It is worth noting that beginning in the year 2020 almonds suddenly appeared to have about 30% less calories than they did the year before. Both walnuts and cashews saw the same decline in the energy content. Nuts themselves didn't change, obviously, but the method used to determine calories did.

It's because the FDA and USDA often still use an old method of measuring calories. Originating in the late 19th century (though the exceptions are made in cases where there's more recent research, such as for peanuts). The late nineteenth century Wilbur Atwater, who was a researcher, wanted to measure the energy contained in foods by burning them, quantifying how much energy it contained before feeding the same food to the people and measuring how much energy was present in their poop and urine. The difference between energy in and energy out, as it were is what became the calorie-calculating number that we have today for macronutrients: nine calories in a gram of fat, and four calories in a gram of carbohydrate and protein.

For the 19th century it was a significant leap in the understanding of energy density in food. However, for the 21st century, this doesn't seem to be quite right.

[Related The truth about measuring calories]

A calorie of fat found in nuts, for instance, doesn't appear to mean the exact as an calorie made from fats from animals. It's still not clear what causes this however, it appears that our bodies aren't able to digest all food products equally, so some calories remain within the food, and then go into our poop. However, they haven't an impact on our waistlines. (We must note that the research into the calories found in nuts was partly funded by various board members, although those who were involved in the research didn't actually design or conduct the research).

The concept of bioavailability has been a relatively recent topic of research, therefore there's a lack of data about what other types of food products we're not measuring. We've learned, for example, that cooking food seems to make the nutrients in it more easily accessible. We also know that our individual microbes within our gut help determine how much energy we extract from our food and this is done by dissolving cell walls within certain vegetables. The Atwater system doesn't take into account any time for cooking food, regardless of how you cook it nor does it account for differences in bioavailability between different kinds of food items. It just goes by the amount of fat, protein, or carbohydrate are contained in the food.

The new studies on nuts don't even employ a more sophisticated method than Atwater used. In essence, they gave almonds (or cashews, walnuts or even cashews) to the participants and monitored their poop levels to determine the amount of energy being absorbed. It's only that the USDA researchers wanted to study one specific food in particular.

until we can find a better method of calculating the amount of energy within a specific food group or food group, the term calorie actually it's a number we've allocated arbitrarily to food items. Do not take it too seriously.