Energy is the ability to do work. Virtually every bite of food gives you energy. The amount of energy in food is measured in calories, the amount of heat produced when food is burned (metabolized) in your body cells. 


Food is the fuel on which your body runs. Without food, you do not have enough energy.


When you read that a serving of food, such as a large banana that has 105 calories, it means that metabolizing the banana produces 105 calories of heat that your body can use for work. 


Which kinds of food have the most calories?

  • One gram of protein has four calories
  • One gram of fat has nine calories
  • One gram of carbohydrates has four calories
  • One gram of alcohol has seven calories

In other words, ounce for ounce, proteins and carbohydrates give you less than half as many calories as fat. That's why high-fat foods, like cream cheese, are high in calories, while lowfat foods, like bagels are not.


Be careful! Sometimes foods that seem to be equally low-calorie really aren't. For example, a chicken breast and a hamburger are both high-protein foods. Both should have the same amount of calories per ounce. But if you serve the chicken without its skin, it has very little fat, while the hamburger is full of it.


Use the comparison tool below to help determine the differences between other foods. If you are on a mobile device, tap here to access comparison tool.

All food provides calories and all calories provide energy, but not all calories come with a full complement of extra benefits such as amino acids, fatty acids, fiber, vitamins, and minerals. Some foods are said to give you 'empty calories'. Best known examples of these are table sugar and ethanol (the kind of alcohol found in beer, wine, and spirits).


Regardless of where the calories come from, if you consume more calories than what you burn off, you will gain weight. If you take in less than you use up, you will lose weight. This applies to everyone.


But how many calories do you need???

You use energy when your body is at rest and when you are actively working (i.e., walking, running, biking, and even brushing your teeth)


When your body is at rest, your body is still working.   Your heart, lungs, and other organs are doing their job and will need to use energy to keep working. To determine the energy that you require when at rest, you will be finding your resting energy expenditure (REE). To find your REE, click/tap here.

When you are active, how active are you?


Activity Level    Sample Activities   
Resting Sleeping, reclining
Very Light Seated and standing activities, painting, driving, laboratory work, typing, sewing, ironing, cooking, playing cards, playing musical instrument
Light Walking on a level surface at 2.5 to 3 mph (4 to 4.8 km/h), garage work, electrical trades, carpentry, restaurant trades, housecleaning, child care, golf, sailing, table tennis
Moderate Walking 3.5 to 4 mph (5.6 to 6.4 km/h), weeding, carrying a load, cycling, skiing, tennis, dancing
Heavy Walking with a load uphill, tree felling, heavy manual digging, basketball, climbing, football, soccer
Exceptionally Heavy Professional athletic training


Adapted by The National Research Council "Recommended Dietary Allowances" 

Based on the type of activity you are doing, it will give you a ballpark idea of how many calories you will need to the the work.

Activity Level Calories Needed for This Work for One Hour
Very Light 80 - 100
Light 110 - 160
Moderate 170 - 240
Heavy 250 - 350
Exceptionally heavy 350+


Adapted by Nutrition for Dummies (p. 32). 

Want to cut calories to lose weight?

Depriving yourself of major calories is not the way to do it. Severe calorie deprivation can cause life-threatening weight loss coupled with nutritional deficiency diseases.


Moderate calorie deprivation, however, produces healthful moderate weight loss.


One pound of body weight equals 3,500 calories. So...

  • If you cut your calorie consumption from 2,000 calories a day to 1,700 and continue to do the same amount of physical work, you will lose one pound of fat in just about 12 days.
  • If you go the other way, increasing your consumption from 1,700 to 2,000 calories a day without increasing the amount of work you do, 12 days later you will be one pound heavier


So, what you need to know is what is the base amount of calories should you be consuming based on your gender, height, weight, and age. Use the daily calorie calculator below to get the approximate amount of calories you should be consuming on a daily basis. This calculator also estimates the amount of calories required when you are doing very light to very heavy (extra active) activities. To access Daily Calorie Calculator on a mobile device, tap here


Calories should be limited to the maximum that you require each day, regardless of the source.  You need to learn to manage your caolories - not let them manage you.


If you have any questions, please feel free to contact us anytime.

Fenelon Athletics 

The personal training studio is now open! 

For more details on one-on-one and/or small group training, please visit our Personal Training page.

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