Number one food that makes you lose weight?

There isn't just one: There isn't a magical food that makes you lose weight. However, if i was pressed to pick one, i would say water since most of us are dehydrated anyway. Drinking water (rather than sugary fruit juices and soft drinks -- including "diet" ones!) will help our metabolism work more effectively. Also, replacing grains and starches with non-starchy, multicolored vegetables would be useful too.