A medical device, comprising: a body data module configured to receive body data; a work level data module configured to determine a first patient work level during a first time period, and a second patient work level during a second time period, wherein the work level refers to the energy consumption of the patient's body or a part thereof; an activity level module configured to determine an activity level of the patient based at least in part on one or more of the body data, a time of day, or an activity level history of the patient, a work level excursion module configured to: determine whether said second work level exceeds said first work level by an amount greater than a first work level excursion threshold; detect a work level excursion, in particular, a pathological work level excursion, based upon a determination that said second work level exceeds said first work level by an amount greater than said first work level excursion threshold, wherein said work level excursion threshold is based at least in part on one or more of a time of day, an environmental condition, an indicator of said patient's hydration status, said patient's body weight and height, said patient's body mass index, said patient's gender, or said patient's age; and detect a pathological state based upon that said second work level does not exceed said first work level by an amount greater than said first work level excursion threshold and a determination that the second work level is outside a work level range expected for the patient's activity level; and a controller to perform at least one of warning of said work level excursion, providing a therapy for said work level excursion, or logging an occurrence of said work level excursion in response to detecting said work level excursion. a body data module configured to receive body data; a work level data module configured to determine a first patient work level during a first time period, and a second patient work level during a second time period, wherein the work level refers to the energy consumption of the patient's body or a part thereof; an activity level module configured to determine an activity level of the patient based at least in part on one or more of the body data, a time of day, or an activity level history of the patient, a work level excursion module configured to: determine whether said second work level exceeds said first work level by an amount greater than a first work level excursion threshold; detect a work level excursion, in particular, a pathological work level excursion, based upon a determination that said second work level exceeds said first work level by an amount greater than said first work level excursion threshold, wherein said work level excursion threshold is based at least in part on one or more of a time of day, an environmental condition, an indicator of said patient's hydration status, said patient's body weight and height, said patient's body mass index, said patient's gender, or said patient's age; and detect a pathological state based upon that said second work level does not exceed said first work level by an amount greater than said first work level excursion threshold and a determination that the second work level is outside a work level range expected for the patient's activity level; and a controller to perform at least one of warning of said work level excursion, providing a therapy for said work level excursion, or logging an occurrence of said work level excursion in response to detecting said work level excursion. determine whether said second work level exceeds said first work level by an amount greater than a first work level excursion threshold; detect a work level excursion, in particular, a pathological work level excursion, based upon a determination that said second work level exceeds said first work level by an amount greater than said first work level excursion threshold, wherein said work level excursion threshold is based at least in part on one or more of a time of day, an environmental condition, an indicator of said patient's hydration status, said patient's body weight and height, said patient's body mass index, said patient's gender, or said patient's age; and detect a pathological state based upon that said second work level does not exceed said first work level by an amount greater than said first work level excursion threshold and a determination that the second work level is outside a work level range expected for the patient's activity level; and a controller to perform at least one of warning of said work level excursion, providing a therapy for said work level excursion, or logging an occurrence of said work level excursion in response to detecting said work level excursion.