What Does the Calorie Rating on Food Mean and How is it Measured?

[Pengwuino]

Ok guys, not sure how many people will know this hehe, but what exactly do the calorie ratings mean for foods? All i can tell is that its how much to heat up the mass... but what does it heat up to? 98.6? And why is it healthier to eat practically 3 feet of sandwhich from subway... say the chicken with no mayo or cheese... then a lil cheeseburger from mcdonalds? I mean its a huge mass vs. this lil cheeseburger. Seems confusing, can someone shed some light on the situation?

 

[chroot]

The Calorie is a unit of energy. Some foods, like lettuce, are nearly all water or other indigestible matter. These foods provide very little energy, so you can eat a lot of them without regret. Other foods, like chocolate, are very dense in calories, and eating a lot is not a good idea.

Just for reference, a gram of carbohydrate has 4 Calories, a gram of protein also 4 Calories, and a gram of fat has 9 Calories.

A Calorie is the amount of energy needed to raise one kilogram [1,000 grams] of water one degree Celsius.

- Warren

 

[Pengwuino]

Yah i know all the physics behidn it but what are the temperatures that the food/drinks are being heated up to?

 

[chroot]

I just told you. The Calorie is a unit of energy, equal to the amount of energy required to raise the temperature of a kilogram of water by one degree Celsius. It has nothing to do with any specific temperature.

- Warren

 

[Pengwuino]

Well there has to be a temperature or else all the claims of like
"Run 40 minutes on this treadmill to burn blah blah Calories". That means it has to be to raised to a certain temperature that maybe people just imply... or i dunno, I am tired lol.

 

[ShawnD]

what exactly do the calorie ratings mean for foods? All i can tell is that its how much to heat up the mass... but what does it heat up to? 98.6?

Calorie is a unit of energy based on SI units; the energy to heat 1g of water by 1C. The American/British counterpart to the Calorie is the British Thermal Unit or BTU for short.
It's just a unit of energy. In countries where SI is used, foods are actually rated in kilojoules instead. Your body can use that energy in whatever way it wants. It can be to heat your body up, move your arms around, or support active transport systems.

And why is it healthier to eat practically 3 feet of sandwhich from subway... say the chicken with no mayo or cheese... then a lil cheeseburger from mcdonalds? I mean its a huge mass vs. this lil cheeseburger. Seems confusing, can someone shed some light on the situation?

Different materials store different amounts of energy for the same mass. Protein (meat) has some energy in it. Carbohydrates (sugar, pasta, rice) also have some energy. Fats (you know what fat is) are very dense in energy. Fiber has basically no energy.

Your sandwich from subway has what in it? It has bread (carbohydrate?), chicken (protein), and vegetables (carbohydrates and fiber). The bread isn't dense at all since it's fluffy, so you can say there's no energy there. Chicken, probably breast, has very little fat in it, so it doesn't really have that much energy in it. Vegetables have a lot of fiber in them, and a little bit of sugar. Overall your sub doesn't have a lot of energy.

Now look at a burger from dink's. Hamburger is more expensive the leaner it is, so you can probably assume dink's uses very fatty hamburger. All that fat adds a lot of calories. Then you have your toppings like ketchup. Ketchup is very high in sugar, so there's some energy right there. Lastly you have your cheese. So what is cheese exactly? It's a dairy product that's basically 40% fat, so there you have a considerable amount of energy.

 

[chroot]

No. The energy required to raise a kilogram of water from 10 to 11 degrees Celsius is the same amount of energy required to then raise it from 11 to 12 degrees Celsius. All that matters is the change in temperature:

\Delta Q = m C \Delta T

- Warren

 

[Pengwuino]

No. The energy required to raise a kilogram of water from 10 to 11 degrees Celsius is the same amount of energy required to then raise it from 11 to 12 degrees Celsius. All that matters is the change in temperature:

\Delta Q = m C \Delta T

Im going to be an ass just so i can save intellectual face in this conversation and say technically, it varies ever so slightly with temperature :P There woo, now i don't seem like a total dolt.

 

[ShawnD]

Let's just forget what a calorie is. Apparently a "Calorie" and a "calorie" are not the same thing; the capital letter is actually significant. Damn that's retarded.

 

[Pengwuino]

Yah... the capital C means kilo in the nutritional world. It doesn't apply to any other field though.

 

[Moonbear]

Yah i know all the physics behidn it but what are the temperatures that the food/drinks are being heated up to?

I may not be interpreting your question correctly, but I'm wondering if you're trying to ask how someone measures the amount of Calories in a given food?

An old-fashioned, simple way to think about it (and sometimes used to demonstrate the concept) is to release the energy of chemical bonds in a sample of the food as heat energy (set it on fire and let it burn ), and when there's nothing left but ashes, you measure how much you increased the temperature of water heated with that burning food. Of course this would need to be done in a closed system so all the heat heated the water, not the surrounding air, etc.

So, basically, calories refer to the energy in the chemical bonds that is available to be released when those bonds are broken, as is done by digestive enzymes. Nowadays, food chemists have ways to determine calories in fractions of the food, not just the whole food, so can tell you how many calories come from fat, or carbohydrates or proteins. The total calories are still what are important in terms of energy in/energy out maintenance of body weight, but because we use different types of nutrients differently, the breakdown in proportions of calories coming from different sources can help ensure you're balancing your diet to include all the nutrients the body will need.

Volume and mass is a poor indicator of caloric content of food (your large sub vs small burger comparison). The reason is that the volume and mass can include both water and air (remember, bread has lots of air pockets in it while meat is very dense). The chemical composition of various nutrients varies, so some have higher energy bonds than others, which means when those bonds are broken, more energy is released = more calories.