What are calories?

What are calories?

Definition of the concept of a calorie isn't difficult: according to the majority of science textbooks, it's the amount of energy needed to increase the weight of one gram of liquid by 1 degree Celsius. But how does it relate in relation to caloriecounts you see everywhere from fast food menus to the nutrition labels of snack bars

When we think about caloriecounts when we look at caloriecounts, we're usually trying to determine how much energy we're putting to our bodies. However, a label on a food item will not provide this, at the very least, accurately. There are too many aspects at play, many of which depend on the person's physical physiology, and others of which we're still trying to figure out.

Consider this: Starting in the year 2020 nuts suddenly were able to provide around 30% less calories than they did the year prior. Walnuts and cashews also experienced the same drop on energy density. Nuts themselves didn't change, obviously, but the method employed to determine calories changed.

This is due to the fact that the FDA and USDA generally still employ the method that was used for centuries for measuring calories. Originating in the late 19th century (though exceptions are made if there's more current research on the subject, like with those who are nuts). In the late 18th century Wilbur Atwater, a scientist from the late 19th century decided that it was time to quantify the energy content in food items by burning the stuff by calculating the amount of energy was in it and then feeding similar food to individuals and measuring the amount of energy that is contained in their poop and pee. The difference between the energy in and energy out, in a sense was the basis for the calorie-calculating figures we use for macronutrients today Nine calories in a gram fat and four in grams of carbohydrate and protein.

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

[Related: The truth about measuring caloriesThe truth about counting calories

A calorie of fat in a nut, for example, doesn't appear to be the same as the calorie that comes from animal fat. It's still not clear the reason for this but it is believed that our bodies can't digest all food products equal, which means that certain calories remain inside the food, and then go into our poop. They haven't had any effect on our waistlines. (We should be aware that the research on calories in nuts was partially funded by different board of nuts, however those who were involved in the research didn't actually design or conduct the research).

The idea of bioavailability only recently been the subject of investigation, and therefore we don't have any information on what other types of food items we're ill-informed about measuring. We know, for instance that cooking food can seem to make the nutrients inside it more accessible. We are also aware that our unique microbes living in our intestines help determine how much energy we extract from our food for example, by breaking down the cell walls in certain vegetables. The Atwater system doesn't take into account all for the cooking process, regardless of how you cook it, nor does it consider differences in bioavailability between different kinds of food. It simply focuses on how many grams of protein, fat or carbohydrate in the food.

The new nut studies don't have a less advanced technique than Atwater utilized. The basic idea is that the researchers gave almonds (or cashews, walnuts or even cashews) to the participants and examined their poop to determine the amount of energy being absorbed. It's just that the USDA scientists were bothering to study one particular food group in particular.

As long as we don't find a better method for quantifying the energy within a specific food group in the near future, a calorie, really is just a number we've given to food items. Be careful not to take it too seriously.