A calorie is really a unit of heat. According to Google, "The energy needed to raise the temperature of 1 gram of water through 1 ?C."
But it really is a measure of how much weight you'll gain from eating a food or lose by doing an exercise.
A pound of weight is equivalent to around 3,500 calories. The goal of the Excel Diet is to have a net reduction of 500 calories per day for 7 days which is a pound a week.
Rule: Eat lower calorie foods over higher calorie foods
One calorie in a food affects people differently. That is because different people burn calories at different rates. One goal of the Excel Diet is to learn what works and what doesn't. This comes from:
Weighing yourself each day
Tracking your weight
Tracking your diet and exercise
Most packaged foods tell you the calories. Just be careful with the Servings.
Calories burned by you is a function of your weight, age, what you do and for how long.
Now many restaurants are displaying the calories of their meals on their menus. Always try to order the lower calorie foods.