Abstract: A conventional flow tube for a metabolic cart is usually a straight length of pipe whose inner diameter is fixed by the respiratory burden imposed by the flow tube on the user, with a smaller diameter imposing a higher respiratory burden. The ratio of the straight flow tube's length to diameter is fixed by fluid dynamics, so increasing the flow tube's diameter causes the flow tube's length to increase. As the flow tube gets longer, it exerts more torque on the user's neck and jaw, creating discomfort. Reducing the flow tube's length causes an undesired increase in the respiratory burden but increasing the flow tube's diameter to reduce the respiratory burden makes the flow tube less comfortable, making the flow tube unconformable, hard to breathe through, or both. Bending the flow tube makes it possible to increase the flow tube's propagation length without increasing the flow tube's lever arm length.

Abstract: A conventional flow tube for a metabolic cart is usually a straight length of pipe whose inner diameter is fixed by the respiratory burden imposed by the flow tube on the user, with a smaller diameter imposing a higher respiratory burden. The ratio of the straight flow tube's length to diameter is fixed by fluid dynamics, so increasing the flow tube's diameter causes the flow tube's length to increase. As the flow tube gets longer, it exerts more torque on the user's neck and jaw, creating discomfort. Reducing the flow tube's length causes an undesired increase in the respiratory burden but increasing the flow tube's diameter to reduce the respiratory burden makes the flow tube less comfortable, making the flow tube unconformable, hard to breathe through, or both. Bending the flow tube, e.g., in an L shape, makes it possible to increase the flow tube's propagation length without increasing the flow tube's lever arm length.

Abstract: Systems, apparatus, and methods related to modeling, monitoring, and/or managing metabolism of a subject include measuring a respiratory quotient (RQ) level in a subject and/or optimizing and executing a nonlinear feedback model to model energy substrate utilization in the subject based on at least one of a macronutrient composition and caloric value of food consumed by the subject, an intensity and duration of activity by the subject, a rate and maximum capacity of glycogen storage in the subject, a rate and maximum capacity of de novo lipogenesis in the subject, a quality and duration of sleep by the subject, and/or an RQ level in the subject.

Abstract: A conventional flow tube for a metabolic cart is usually a straight length of pipe whose inner diameter is fixed by the respiratory burden imposed by the flow tube on the user, with a smaller diameter imposing a higher respiratory burden. The ratio of the straight flow tube's length to diameter is fixed by fluid dynamics, so increasing the flow tube's diameter causes the flow tube's length to increase. As the flow tube gets longer, it exerts more torque on the user's neck and jaw, creating discomfort. Reducing the flow tube's length causes an undesired increase in the respiratory burden but increasing the flow tube's diameter to reduce the respiratory burden makes the flow tube less comfortable, making the flow tube unconformable, hard to breathe through, or both. Bending the flow tube, e.g., in an L shape, makes it possible to increase the flow tube's propagation length without increasing the flow tube's lever arm length.

Abstract: Systems, apparatus, and methods related to modeling, monitoring, and/or managing metabolism of a subject include measuring a respiratory quotient (RQ) level in a subject and/or optimizing and executing a nonlinear feedback model to model energy substrate utilization in the subject based on at least one of a macronutrient composition and caloric value of food consumed by the subject, an intensity and duration of activity by the subject, a rate and maximum capacity of glycogen storage in the subject, a rate and maximum capacity of de novo lipogenesis in the subject, a quality and duration of sleep by the subject, and/or an RQ level in the subject.

Abstract: An apparatus for monitoring the consumption of fluid by a user, particularly fluids being drank from a container. The apparatus may be used with wide variety of container types. The fluid monitoring unit uses a pair of gears in rotational engagement with each other such that fluid passes around them and rotation of at least one gear is indicative of fluid consumption. The gears in at least one exemplary embodiment are arranged to have low frictional resistance with respect to each other and their respective axles such that the gears quickly and easily rotate and over a wide fluid flow range. This allows the apparatus to accurately and consistently monitor fluid flow from very low flow rates to high flow rates and therefore provide very reliable consumption information. The apparatus in one exemplary embodiment includes an electromagnetic drinking straw embodiment that allows a user to monitor the consumption of fluids from virtually any container type.