CHAPTER 2 LITERATURE REVIEWDefinition of CalorieAccording to Ayoob (2009), a calorie can be defined as a unit of thermal energy that the human body uses as energy to produce the heat. This energy fuels the human body to give it strength in its daily activities. In scientific terms, there are two types of calories: small calories and large calories (Nordqvist, 2013). A small calorie (symbol: cal) - 1cal is the amount of energy required to raise a gram of water by one degree Celsius. One large calorie (symbol: Cal, kcal) – 1 Cal is the amount of energy required to raise a kilogram of water by one degree Celsius. 1 large calorie (1 kcal) = 1,000 small calories. Calories can be found in fats, carbohydrates and proteins. . The main source of calories comes from daily food intake. Too much calorie intake can lead to weight gain and too little calorie intake can lead to weight loss. Therefore, in order to maintain your body weight, consume as many calories as your body needs. (Jensen, 2001). The body breaks down food molecules to release the energy they contain. This energy is necessary for life functions such as movement, thinking, and growth – anything that requires the use of energy. The body stores energy it doesn't need in the form of fat cells for future use. Calorie Burning Factors There are several factors that affect calorie burning during the walking phase: the quality of the walking surface, your weight, height, age, walking distance, step length and speed. . (Travis, 2013) Surface Elevation – More calories are burned as the incline of the walking surface increases and fewer calories are burned as the walking surface decreases. Weight – Greater body weight exerts more effort and expends more energy running. ...... middle of paper ...... determine how many calories you should eat to maintain or lose weight. Retrieved March 24, 2014 from www.coachme2health.com: http://www.schools.utah.gov/cte/documents/facs/conference/S12/FN_Jensen_CalculatingCalories.pdf Kawahara, N. (nd). Monitoring daily energy expenditure using a 3-axis accelerometer with a low-power microprocessor. Nordqvist, C. (August 11, 2013). Medical News Today. Retrieved March 24, 2014 from What Are Calories? What is a calorie? : http://www.medicalnewstoday.com/articles/263028.php Owusu, E. (2009). ACCESSORY: Password Inference Using.Taylor, LL (2009). Basal metabolic rate. Retrieved from ShapeFit: http://www.shapefit.com/basal-metabolic-rate.html Travis, C. (July 22, 2013). Factors affecting the calories you burn when you run. Retrieved from http://voices.yahoo.com/factors-affecting-calories-burn-running-12236202.html