exercise is the way to do it
at least you are doing it together whic is better than her sitting at home worrying

the only way you are going to lose wieght is to burn off more than you eat, and you tend to eat until your stomach is full, so if you eat heavy foods or you eat light foods, the capicity of your stomach is still going to be the same

this is why lrabbit food makes you lose wieght

for more informative stuff, try posting in the fitness room and see what you can do because there may be special way to counteract this problem rather than doing normal stuff to try and shift wieght