What Is a Calorie?
In simplest terms, a calorie isn’t any kind
of “thing” whatsoever. Calories are not like proteins,
or carbohydrates, or vitamins, or any
kind of nutrient.You can find protein in food. You can find vitamins in food. Yet, you cannot find a calorie in any food at all. Calories do not exist in that way.
Calories are units of measurement. They are
like inches, miles, ounces, degrees of
temperature, pounds, tons, gallons, and acres. They are just a way of
understanding how much of something is present. In the case of calories,
this something is energy.
The amount of energy
associated with any set of events can be measured
in terms of calories.
Calories don’t have to involve food. For example, there are a specific number of calories
that any electrical wire can carry without
catching fire. There are a specific number of calories that strike the earth
each day in the form of sunlight. Calories are not found in food. They are only related to food insofar
as food has the
potential to be measured as a form of energy.
Can Food Calories Be Accurately Measured?
The other
websites are accurate?
Unfortunately, the answer is both yes and no. Yes,
there are solid scientific studies using real foods and real laboratory
conditions to support the specific
calorie numbers that appear in the USDA data- base and in other published lists of food and calories.
This research can be very high quality, sophisticated, and scientifically sound. But it is research based on laboratory
analysis not research based on the passage of real food through a person’s digestive tract. Unless food gets digested, it cannot provide
us with any calories (energy).
When food calories are measured in a lab, a device called a bomb calorimeter is used. This device measures energy in the form of heat. Within this device, a highly oxygenated, sealed chamber containing a food sample is floated in water. An electrical current is used to ignite the food-oxygen mixture, and as it burns, the water
surrounding the floating chamber heats up. The number of calories in the food is determined by the change in water temperature. A high- calorie food gets the water hotter by releasing more heat energy than a low-calorie one.
Even though calories can be measured accurately in a lab where they appear to be a fixed attribute of food, once we get inside a living person, and a uniquely biochemical digestive tract, all bets are off when it comes to a rigid set of calorie predictions.
When food calories are measured in a lab, a device called a bomb calorimeter is used. This device measures energy in the form of heat. Within this device, a highly oxygenated, sealed chamber containing a food sample is floated in water. An electrical current is used to ignite the food-oxygen mixture, and as it burns, the water
surrounding the floating chamber heats up. The number of calories in the food is determined by the change in water temperature. A high- calorie food gets the water hotter by releasing more heat energy than a low-calorie one.
Even though calories can be measured accurately in a lab where they appear to be a fixed attribute of food, once we get inside a living person, and a uniquely biochemical digestive tract, all bets are off when it comes to a rigid set of calorie predictions.
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