Weight loss can have many causes and I think it is best to have an evaluation by a physician and be tested for the most common problems such as diabetes and Celiac Sprue. The large Tapeworms we get from eating undercooked pork and beef might be diagnosed from a lab stool exam as they produce thousands of ova but the smaller Tapeworms people acquire from pets, undercooked fish and other sources may not show up on regular lab exams. Anemia and weight loss are more likely with the larger tapeworms.
Self diagnosis of problems and self treatment works for some people but it is not very scientific and is often attempted when there seems to be no other way to regain health. In general, health improvement programs do help people become healthier but may not stop a health condition caused by somethng that the programs cannot treat.