Does this app automatactly reduce our calories as we lose weight ?

I have been using MFP for four months and my experience is that each time I lose 10 pounds I am prompted with the option to update my calorie goals. You can also force an update based on your current information as described in the MFP help at http://myfitnesspal.desk.com/customer/portal/articles/689990-how-can-i-force-my-calorie-goals-to-update-.

Hope this helps.