Eat to lose weight? The statement sounds self-contradictory but it is true. At least in some cases. Celery is one of the vegetables I hate most, along with carrot, pumpkin, broccoli, chive, caraway, bell pepper... But celery is the so-called negative-calorie food which burns more calories than those are absorbed during the digestion. The same logic can be applied to cold diet soft drink because the body has to give off more energy to warm the liquid to body temperature.

This list of negative-calorie food doesn't suggest a proper way to cook those food. I think to boil might be an appropriate way. That's how I cook spinach all the time and it is yummy with a little bit salt. You can also add some seasonings to spice or salad dressings if you like. But be sure it is fat free.