What are calories?

What are calories?

Definition of the term calorie isn't hard: according to most science textbooks, that's how much energy needed to raise one gram of water an inch Celsius. However, how does this relate and relate to caloriecounts that are displayed on everything from menus for fast food to the nutrition labels of snack bars

When we think about caloriecounts, we're generally hoping to understand how much energy we're pouring to our bodies. But a nutrition label cannot be able tell you this, at the very least, precisely. There are a myriad of factors involved, some of that are influenced by an individual's physiology, and others that we're still finding out.

Think about this: In 2020 nuts suddenly were able to provide around 30 percent less calories than they did the year prior. Nuts and cashews both experienced the same decline in energy density. Nuts ' density didn't change of course, but the method employed to calculate calories did.

This is because those who work for the FDA and USDA often still use the method that was used for centuries for measuring calories. This method was created in the 19th century (though exceptions can be made when there's more current research available, for instance, for some nuts). In the 18th century Wilbur Atwater, decided to determine the amount of energy in foods through burning the ingredients in order to determine how much energy was in it and then feeding the same food to humans and then observing how much energy was contained in their poop and urine. The difference between the energy that was in and the energy that went out, as it were, became the calorie-calculating numbers that we currently use for macronutrients Nine calories per gram of fat, and four each in a gram of carbohydrate and protein.

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

[Related: The truth about counting caloriesIt's a fact!

A calorie of fat in a walnut, for instance, doesn't appear to have the identical thing as an calorie of animal fat. Although it's not clear the reason for this but it is believed that our bodies can't digest all food products in the same way, meaning that certain calories remain in the food and exit in our feces, but haven't had any effect on our waistlines. (We should be aware that the research on calories-in-nuts was partially funded by various nuts boards, but they didn't conceptualize or perform the studies themselves).

Bioavailability is only recently been the subject of research, therefore there's a lack of data on what other types of food items we're ill-informed about measuring. For instance, we know that cooking food appears to make the nutrients contained in it more available. We also know that our personal gut microbes help determine how much energy we extract from our food, like by dissolving cell walls within certain vegetables. The Atwater system does not account at any time for cooking food, and even less, the method you use to cook it or the differing bioavailability of different kinds of foods. It's all about the number of grams of protein, fat, or carbohydrates are present in the food.

The new nut studies don't even employ a more sophisticated method than Atwater used. In essence, they gave almonds (or walnuts or cashews) to participants, and they measured their poop for how much energy was absorption. However, the USDA scientists wanted to look at one food item in particular.

If we aren't able to find a more effective method for quantifying the energy contained in each food group and a calorie is, in reality, is a number we've given to food. Try not to be too concerned about it.