What are Calories Millions of adults carefully count the calories they eat every day For most the reason is that they want to lose weight or stay at the same weight Some people on the other hand are thin and weak They may have lost weight because of an illness They need to increase their calories to 4 gain weight and build their strength Calories can be confusing People think about calories when they think about their weight but calories are not a measure of weight They measure energy Humans take in energy through food The human body uses food A woman uses a computer app to help count the number of calories in a complete serving of a meal
energy as fuel for its activities People call this process burning calories Think About It Instead of measuring the calories people consume and the energy they burn why don’t doctors and dieticians simply keep track of people’s weight Activities that burn calories can be hard work for example concentrating on homework or moving heavy boxes They also can be as easy as breathing and walking Even sleeping takes a small amount of energy Each activity burns a certain number of calories If people burn more calories than they consume in their food each day they lose weight If they burn fewer calories than they consume their bodies convert the unused calories to fat and store it That stored fat increases their weight Running and playing sports are good ways to burn calories Exercise is important for healthy living 5
Calories in human Diets The word calorie has different meanings One meaning refers to scientific measurements of heat and water In science a calorie is the amount of heat energy needed to raise the temperature of 1 gram 0 035 ounce of water by 1 degree Celsius 1 8 degrees This small device is called a calorimeter It measures the amount of heat released from a liquid 6
Wilbur O Atwater was a chemist who lived a century ago He developed a system to measure the caloric values of foods Fahrenheit The more common meaning refers to the amount of energy contained in food One food calorie is actually a kilocalorie It equals one thousand of the calories used in scientific measurements Compare and Contrast Which form of exercise do you think burns more calories rowing a boat or walking 7
