No, metformin does not cause weight loss. The weight loss that may be observed in patients taking metformin is associated with an improvement in diet and increase in physical activity. In other words, when people are diagnosed with diabetes and prescribed metformin, they may also change their diet. I still take metformin to help with weight loss. It works! Its been 2 and a half months since the surgery and ive lost 55 pounds. I will let you know if it causes me to resume having periods; please let me know how you're doing also. It disgusts me that the majority of physicians adopt a blame the patient.