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Measuring calories in Food
We hear about them everyday: calories. Food has them. We usually eat more of
them than are good for us. We want to burn them as rapidly as possible to
look our best. But what are they? A calorie is the amount of energy required
to raise the temperature of one gram of water (one milliliter) by one degree
Celsius. We also use calories to measure the amount of energy we get from
the food that we eat.
Different foods contain varying numbers of calories. One gram of protein or
carbohydrate has 4 calories. The same amount of fat has 9 calories. To
further compound matters, there are empty and nutritional calories. A cup of
orange soda has fewer calories than one cup of orange juice, but its
calories are empty, they have no real nutritional value.
Calories in food have been scientifically measured. You can determine this
for yourself by burning a cashew, for example, underneath a container of
100ml of water. Record the weight of the cashew before (W1) and after (W2)
burning. The difference (W1-W2=W3) is the amount of energy expended. Next,
record the temperature of the water when the cashew is lit (T1) and again
when it has burned out (T2). The amount of the remaining cashew (W3) and the
temperature increase (T2-T1=T3) will be equal. Unless you have constant
access to a calculator, figuring out the caloric value of foods for yourself
is going to be difficult and time consuming.
Fortunately, we don’t have to go to this much trouble. By law, the
manufacturers of foods are required to place nutrition panels on the
packaging to tell you how many calories are in one serving size. You may see
caloric values on the menus of some restaurants and fast food stores.
Another way is to use the Fat and Calorie Calculator from
FoodNetwork.Com. It will tell you the caloric value of foods and how
this changes by the way food is prepared.
Let’s look at one food item, a chicken drumstick (1 pound, ready-to-cook):
Raw (meat and skin): 70 calories, 36 being from fat.
Roasted: 66 and 27.
Stewed: 69 and 36.
Flour fried: 71 and 36.
Batter fried: 115 and 63.
Raw (meat only): 44 calories, 9 being from fat.
Roasted: 44 and 9.
Stewed: 47 and 18.
Fried: 48 and 18.
Breaded and fried (two pieces from a Fast Food Chain): 430 and 244
You can see three things quite easily. Frying, leaving the skin on, and
coating with a batter increases the total number of calories. Chicken from a
fast food chain has 6 times the calories of raw chicken consisting of meat
and skin. We should, therefore, prepare our foods by baking, roasting or
stewing them at home to get the most nutritional calories and the least
empty calories.
References
Blake, Joan Salge. (2007). The Pros and Cons of a Low Calorie Diet.
FoodNetwork.com.
http://www.foodnetwork.com/food/lf_hl_low_calorie/article/0,2661,FOOD_21616_3857806,00.html
FoodNetwork.Com. (2007) Fat and Calorie Calculator.
http://www.foodnetwork.com/food/ck_fat_calorie_calculator
International Food Information Council. (2003) Calories Count: Balancing the
Energy Equation. Food Insight.
http://ific.org/foodinsight/2003/ma/caloriesfi203.cfm
LeWine, Howard. (2005). Burning Calories with Exercise. Aetna InteliHeath.
http://www.intelihealth.com/IH/ihtIH/WSIHW000/35320/35322/423294.html?d=dmtHMSContent
Step Up to the Plate. (2005). Calories: Pumping Energy into a Healthier
Balanced Life.
http://www.stepuptotheplate.net/Modules/Calories.asp
USC.edu. (2004). Burning Calories – The Energy in Food. USC Courses: BISC
150.
http://bioweb.usc.edu/courses/2004-fall/documents/bisc150-lab_burningcal.pdf
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