Excess sodium and sodium seasonings combined with fat can cause water retention. For males, it is most noticeable in the abdominal area. The thighs, hips, and buttocks are affected on females. The body's metabolism basically goes into shutdown mode when you become inactive. This inactivity causes calories to build up and ultimately produce excess and unwanted bodyfat.
Lack of exercise limits metabolism speed.
The metabolism must reach a certain speed in order to burn fat. Weight training is perfectly fine, but isn't needed to burn fat. It is best to do cardio on an empty stomach. By morning, blood sugar and carb levels low. This empty stomach training forces the body to look for an alternate energy source.