Computer software for estimating and displaying a graphical summary of weight gain, caloric expenditures, and weight loss scenarios arising as a result of an activity, fitness and dietary regime; computer software for continuously analyzing the functional behaviors of the muscular, skeletal and cardiovascular systems of a person and for displaying feedback; computer software for the display and monitoring of projected weight gain and weight loss scenarios of individuals participating in exercise, weight loss and obesity, and wellness programs; computer software to be used with a personal digital assistant (PDA) for monitoring physical activity and displaying feedback which guides the user through a daily activity regime or exercise of program; personal digital assistant (PDA) for receiving physical activity data to display feedback that guides the user; and portable electronic fitness monitors in the nature of joule expenditure monitors, namely, calorimeters