CALORIES

• A calorie, or kilocalorie, is a unit used to measure energy.  Specifically, a calorie is the amount of energy needed to raise 1 kg of water by 1 degree Celsius.  Calories in our diet come from fat, protein, carbohydrates, and alcohol.  Carbohydrates and protein contain 4 calories per gram.  Each gram of alcohol contains 7 calories.  Fat has a whopping 9 calories per gram.
  
  
• Since calories are simply a measurement of energy, this question could be re-worded to ask, "How does the body use energy?"  Obviously, the body uses energy to perform all of its functions.  If we consume more energy (calories) that our bodies need, the excess is stored as fat.  This body fat can then be broken down later to provide energy to our bodies when a food shortage exists.  If you would like to lose excess body fat, you simply need to create an energy shortage by consuming a low-calorie diet or by increasing your activity level.
  
  
• Each person is different. The amount of calories needed depends on age, gender, height, weight, goals, body composition and metabolic rate.  You can estimate the calories needed to maintain your body weight by using the Harris-Benedict Equation.  After calculating the number of calories needed to maintain your weight, you can then determine the calories needed to lose weight.  Each pound of body fat stores roughly 3500 calories.  If you would like to lose one pound per week, you would need to create a calorie shortage of 3500 calories per week or 500 calories per day (3500 calories per week / 7 days per week = 500 calories per day).
  
  
• The Harris-Benedict Equation will help you calculate your Basic Metabolic Rate( BMR) or the amount of calories you need to consume daily in order to maintain your body weight at a normal physical activity level( without exercising).
  

• To calculate daily calories needed based on level of activity, multiply BMR( Kcal obtained above) by a factor with a value between 1.2 (lowest level of activity) and 1.9 (highest level of activity). If you want to loose weight substract 500 cal/day from the total amount obtained above( to loose 1 lb/week) or 250 cal/day( to loose 1 lb every 2 weeks).
  
  
• The number of calories in a food item depends on the quantity of carbohydrates, fats, protein, and alcohol.  Ideally, we should consume foods with a relatively high number of nutrients per calorie, or nutrient-dense foods.  Otherwise, we are eating "empty calories".  Soft drinks are a good example of empty-calorie foods.  They supply the body with calories but very few nutrients.  Nutrient-dense foods include unprocessed food items, fruits, vegetables, etc.