The Deal with Calories | Crossover with SciShow’s The Deal with Fat
Hello and welcome to SciJoy. Today we are
going to count calories using a blowtorch. [Intro Music] On SciShow, Hank taught you
The Deal with Fat and here we are going to teach you The Deal with Calories. A calorie
is a measure of energy. Energy is the ability to get stuff done or the ability to do work.
And when you are talking about nutrition, it is the ability to keep yourself warm, build
components, or repair things. To measure the amount of calories in food it is usually set
on fire. They use something called a bomb calorimeter. It is going to be a container
filled with water. And there is going to be a smaller container. That is going to pressurized
and seal. You are going to put the dehydrated sample of food inside of it, and you are going
to ignite it. This is going to heat up the bath of water that is surrounding it. Since
a calorie is defines as the amount of heat it takes to raise one gram of water 1 degree
celsius, the heating of the water correlates to how many calories are inside that sample
of food. Hank said per gram, fat has about twice as many calories as carbohydrates do.
We wanted to test this out. We don’t have a bomb calorimeter, but we do have a blowtorch.
We used 3 grams of sugar as our carbohydrate. We lit it on fire and placed it under a can
of water. The fire burnt out quickly and the temperature rose about 10 degrees. We learned
from prior experimentation, that we had to get the sugar into a liquid state so it would
ignite. For the fat we used 3 grams of olive oil. We preheated it with a torch so the oil
would burn. As the liquid cooled, we made sure to heat it up with the blowtorch again.
Overall, the temperature rose about 38 degrees. These aren’t laboratory quality results, but
the basic concept that fats stores substantially more energy than carbohydrates was evident.
You can test small quantities of food at home using a lighter or a match. Make sure you
have adult supervision and somebody who know the flammability of different foods and knows
how to put out various kitchen fires. Even if we use a bomb calorimeter, there are still
a couple of problems we are going to run into. Not all the food you eat is going to be directly
converted into energy. Some of it is going to be lost during digestion and some of it
is going to be excreted. And you don’t want to put every piece of food you are ever going
to eat into a bomb calorimeter and figure out its calorie content. So Wilbur Atwater
helped us out with some estimation methods. He tested thousands of samples of food and
gave us some guidelines to go by. Atwater measured and analyzed fecal and urine outputs.
And from this he created The Atwater factors. And while the protein, carbohydrate, and fat
caloric values might change form food to food, in general if you eat a varied diet it is
going to average out to be about 4 Calories per gram for proteins and carbohydrates and
about 9 Calories per gram for fats. And this means is you know the basic ingredients of
you food, or you know about the fat, carbohydrate and protein content that you are going to
have, you can pretty much calculate the caloric value of any food. Atwater also determined
how many calories humans burn. He put volunteers in chambers and measured the room temperature
rise as they released body heat. And from this he could figure out how many calories
that you were burning during different activities. He also monitored your CO2 and oxygen levels,
because oxygen is needed for metabolism. And this is how your body converts the food you
eat into energy that you can actually use. And by doing this he correlated body heat
and respiration so now we can just monitor your oxygen levels to know how many calories
you burn. If you have any questions or comments or if you do this experiment at home, please
let us know in the comments below. You can also tell us on Twitter, Facebook, Tumblr,
Instagram, or Reddit. And remember, keep exploring!