Can mitral valve prolapse be related to unintentional weight loss?

Probably not. Mitral valve prolapse is a description of how the valve closes. It does increase the incidence of mitral regurgitation (leaking valve). I have not heard of it causing a patient to loose weight. I have seen patients with severe mitral regurge gain weight (retaining extra water from heart failure). I would look at other causes and discuss eith your physician.
NO. Many patients with mvp are thin and hyperactive. You need to look for other causes for weight loss.