What are calories?

What are calories?

Definition of a calorie is simple. According to most textbooks on science, that's how much energy required to raise a gram of drinking water up to one degree Celsius. But how does that relate and relate to caloriecounts that are displayed on everything from fast food menus to snack bar nutrition labels

When we consider caloriecounts when we look at caloriecounts, we're usually trying to determine the amount of energy we're pumping to our bodies. But a nutrition label will never give you this, at the very least, precisely. There are a myriad of factors at play, many of which are dependent on an individual's physiological condition, and others that we're still figuring out.

Think about this: In 2020 the almonds suddenly seemed to have around 30 percent fewer calories than they did in the previous year. The walnuts and cashews experienced similar declines of energy density. Nuts didn't suffer, however, the method used to calculate calories did.

This is due to the fact that there's a reason that the FDA and USDA frequently use the method that was used for centuries for measuring calories. The method was first developed in the late 19th century (though there are exceptions if there's more recent research, such as for these nuts). In the 20th century Wilbur Atwater decided to gauge the amount of energy in foods by burning the stuff by calculating the amount of energy it contained as well as feeding the same food items to people and measuring the amount of energy that was in their poop and urine. The difference between energy that was in and the energy that went out, in a sense is what became the calorie-calculating number that we have today for macronutrients 9 calories in one gram of fat, and 4 calories in a gram of carbohydrate and protein.

For the 19th century, this was a huge leap in our understanding of energy density of food. However, in the 21st century, it doesn't quite add up.

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A calorie of fat found in nuts, as an example, isn't likely to have the identical thing as the calorie that comes from animal fat. It's still not clear what causes this and why, it's likely that our bodies can't break down all food items equally, which means some calories remain inside the food and exit in our poopand never have had any effect on our waistlines. (We are reminded that the research on calories-in-nuts was funded in part by various Nut boards, even though those who were involved in the research didn't actually design or perform the studies themselves).

The concept of bioavailability has been a relatively recent topic of research, which means we don't have any information about other food items we're not measuring. We know, for instance that cooking food can seem to make the nutrients that are in it more easily accessible. We are also aware that our unique microbes in our gut 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 cooking food, or even the method you use to cook it nor does it consider variations in bioavailability among different types of foods. It's all about how many grams of fat, protein, or carbohydrates are present in the food.

The new studies on nuts don't utilize a more advanced technique than Atwater utilized. The basic idea is that the researchers fed almonds (or walnuts or cashews) to the participants and examined their poop to determine how much energy was consumed. It's only that the USDA scientists wanted to study one specific food in particular.

As long as we don't find a better method for quantifying the energy of any food category or food group, the term calorie actually is just a number we've given to food items. Try not to think about it too much.