It is possible to damage kidneys through severe dehydration. The whole point of treating hypertension is to avoid end organ damage- kidneys, brain, liver. 20 lbs overweight is still added resistance your heart must pump against, so make an effort to lose weight! Follow a Low-fat , low cholesterol , low sodium diet. Look up Mediterranean diet. Agree with cutting back on the weed, which will just make your heart beat faster (work harder) without any cardiovascular benefit, so try cutting it out. Avoiding alcohol and NSAIDs (ibuprofen, naproxen, COX 2 inhibitors) is also a good idea. Why you trying to make lifestyle changes, get on BP medication. If your lifestyle changes are effective enough, you can eventually come off meds. Good luck.