For example, if you consume 500 extra calories per day for a week without changing the level of physical activity, then your weight will increase about 1 pound per week (5 days multiplied by 500 calories = 3,500 calories, or the amount of calories to produce 1 pound of weight body). Conversely, if you reduce 500 calories per day for 1 week or burn 500 extra calories per day by way of exercising for a week, then your weight will drop about 1 pound.
All the physical activities you do throughout the day will be added to the BMR (basal metabolic rate) to determine the total calories you burn each day. For example, a person weighing 170 pounds who spent 45 minutes to walk is expected to burn about 300 calories. Same amount of time if spent on cleaning the house is expected to burn about 200 calories and mowing the lawn for 45 minutes will take up about 274 calories.