While atorvastatin and other statins are not known to directly cause weight gain, some of their side effects can potentially lead to weight gain. While taking atorvastatin, it is not uncommon to experience mild muscle aches and weakness, which can make physical activity more difficult. A lack of physical activity has the potential to lead to weight gain. The second factor that often contributes to weight gain among patients taking atorvastatin is a false sense of security. It is possible to assume that taking a cholesterol-lowering drug makes it okay to make poor dietary choices and that simply is not true. Over time, these choices can lead to weight gain.