Energy From Food – How Much Do We Need?
Whether we think about it or not the reason we eat is to get energy from food. We cook those delicious meals to get energy from our food to fuel our body’s processes to carry out our daily tasks of living.
Energy is needed for muscle movement and for nerves to send and receive messages throughout the body. The three nutrient classes that are our energy sources carbohydrates, fats, and proteins in the order of usage, with carbohydrates being the first fuel source to be tapped first as glucose, a simple sugar, next are fats as triglycerides, then proteins.
Nutrients when taken in through food are broken down in a process called metabolism to produce energy in a form that the cells of the body can use.
But how do we measure the energy that is available to us in food in order to determine how much we need to run our body processes and to maintain good health? That energy in food is measured as the potential energy in food. The body’s use of energy is measured in units of heat called kilocalories where one kilocalorie equals 1,000 calories. This measurement can help us to determine how much energy we would need to fuel our daily activities.
As part of determining how much food we need to consume to get the right amount of energy from it, scientists have found that carbohydrates and proteins yield 4 kilocalories for every gram of carbohydrates consumed and that fats yield 9 kilocalories for every gram of fat consumed.
Although the amount of energy that food yields is technically measured in kilocalories, common everyday usage refers to this measurement as calories, which is not really true, but has become the term used. So, it has now become popular to use calorie as a general term for energy and kilocalorie as the specific measurement or unit of energy. As a result food labels, diet books and other sources of nutrition information use the term calorie not kilocalorie.
Calculating The Energy From Foods
There are some formulas that can be used for those that are counting how many grams of a particular food item they should eat to obtain a certain amount of energy.
Grams carbohydrate x 4 kilocalories/gram = kilocalories
+ Grams protein x 4 kilocalories/gram = kilocalories
+ Grams fat x 9 kilocalories/gram = kilocalories
= Total kilocalories available from food
For example let’s assume that we have a breakfast consisting of:
|Fat (gms)||Carbohydrate (gms)||Proteins (gms)|
|Margarine (soft spread)||9||0||0|
|Bacon (pork, 1 slice)||9||9||6|
|Egg (1 scrambled)||7||1||7|
|Orange Juice (refrigerated)||1||25||2|
Applying the formula:
38 grams carbohydrate x 4 kilocalories/g = 152 kilocalories
18 grams protein x 4 kilocalories/g = 72 kilocalories
27 grams fat x 9 kilocalories/g = 243 kilocalories
Total kilocalories = 467 kilocalories
The second formula allows for the calculation of how much carbohydrates, proteins, and fats contribute to the total, that formula is:
Gram carbohydrate x 4 kilocalories/gram = kilocalories/total kilocalories x 100 = % carbohydrate kilocalories
Gram protein x 4 kilocalories/gram = kilocalories/total kilocalories x 100 = % protein kilocalories
Gram fat x 9 kilocalories/gram = kilocalories/total kilocalories x 100 = % fat kilocalories
The percent(%) contributed by each nutrient is:
38 grams carbohydrate x 4 kilocalories/g = 152 kilocalories/467 x 100 = 32.6% carbohydrate
18 grams protein x 4 kilocalories/g = 72 kilocalories/467 x 100 = 15.4% protein
27 grams fat x 9 kilocalories/g = 243 kilocalories/467 x 100 = 52% fat
The Dietary Guidelines for Americans 2010 list the recommended percentages of carbohydrates, fats and proteins for various age groups as:
|Young Children (1-3 years)||45-65%||5-20%||30-40%|
|Older Children/Adolescents (4-18 years)||45-65%||10-30%||25-35%|
|Adults (19 years and older)||45-65%||10-35%||20-35%|
By looking at these guidelines we might conclude from our example that to get the best benefits of energy from food for this breakfast, we might want to add more carbohydrates, leave proteins as they are and reduce fat which is way too high in this breakfast, looking at the guidelines for adults 19 and over.
This is one way that we can cook those great recipes, obtain the energy from food that we need, maintain a healthy weight, and good health relatively free of disease by paying attention to how much of the nutrients from foods we include in our daily diet.
For more information about energy from food click on the link to Wikipedia.org
For other information on nutrition including energy from food some great references are:
• Nutrition – Fourth Edition by Paul Insel, Don Ross, Kimberley McMahon, and Melissa Bernstein
• Dietary Guidelines for Americans 2010 – www.dietaryguidelines.gov
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