Weight loss may come naturally with treatment. I had gained tons of weight while undiagnosed with lyme. I am losing weight now. Don't know if it is just a different stage with lyme or what. Some people gain with it, some lose with it, some do both like me. But in answer to your question, it is okay to reduce your calories to lose weight while on the meds. You just have to look at the drug info sheet for each of your meds to make sure there are no specific conflicts. For instance, mepron needs to be taken with fats, so you can't go on a really low fat diet if you are on that med.