Methods and systems may be used for measuring fluid status in a subcutaneous tissue space. Systems may include a wearable device or a diagnostic tool. The device may include a processor, an emitter, and a detector. The emitter and the detector are coupled to the processor. The emitter may be configured to emit a signal into a subcutaneous tissue space of a subject. The signal may be reflected by the subcutaneous tissue space. The detector may be configured to receive the reflected signal. The processor may be configured to determine a fluid status in the subcutaneous tissue space. The fluid status in the subcutaneous tissue space may be based on an energy level of the reflected signal.