A nutrition and activity management system is disclosed that monitors energy expenditure of an individual through the use of a body-mounted sensing apparatus. The apparatus is particularly adapted for continuous wear. The system is also adaptable or applicable to measuring a number of other physiological parameters and reporting the same and derivations of such parameters. A weight management embodiment is directed to achieving an optimum or preselected energy balance between calories consumed and energy expended by the user. An adaptable computerized nutritional tracking system is utilized to obtain data regarding food consumed, Relevant and predictive feedback is provided to the user regarding the mutual effect of the user's energy expenditure, food consumption and other measured or derived or manually input physiological contextual parameters upon progress toward said goal.