Do statins (for lowering cholesterol ) cause one s metabolism to slow down? I am 60, I swim 1 1/2 miles (vigorously) 5 times a week, eat a predominant Mediterranean plant based diet , hardly any sugar, white flour, or grains. I have been on this regime for 1 1/2 years, lost weight and many inches. However, about 3 months ago, I began to take prescribed prevastatin and I m gaining weight. When I scale back on calories even more, I gain more weight? What s going on here? It s almost as if all my exercise is going for naught.