My doctor advised me to have a healthy and low calorie dinner. I have seen a quick easy dinner recipe which is very less in calorie and high in fiber. The chef used the normal vegetable oil in the cooking process. But I want to know, can I use olive oil in the place of simple vegetable oil to cut down more calories? Will cutting down the calories below minimum will make the dish unhealthy? What do you think I should do? How many calories does one need to have in a day?