The Chinese have an old saying according to which, we eat first with our eyes, then our nose and finally our mouth. When we come to think of it, the adage sort of holds true.  In order to achieve a holistic experience of food, all the senses should be utilized equally. Hence, visual appeal of food is imperative. In movies, especially the ones in which food is an important part of the plot, the presentation is prioritized more than anything. That’s where food stylists come into picture.  As far as the dishes are concerned, there is a little deception involved and there is more to it than what meets the eye.

If you’ve watched the movie Chef, you know how much those Cubano sandwiches and yuca fries were important for the essence of the film. According to the movie’s official food stylist Melissa McSorley, in the scenes where an actor is shown eating it was most difficult for the her because the food needed to be presented perfectly on each take. For Chef, McSorley and her team made 800 Cubanos for one scene. And that’s not where it ended. A movie food stylist employs several tricks to make dishes on-screen look delicious.
There’s a fake everything quite far from your imagination. There are fake oysters that are actually colored and airbrushed flan. There’s fake ice cream (sacrilege?), which is surprisingly tissue paper made to look delectable by using the right camera angles and reflectors. Fake ice cream is also made by using shortening and powdered sugar. Celebrated food stylist Susan Spungen who has worked in quite a few movies including Julie & Julia has talked about the importance of replacement food in several interviews. 
Closer home, in the movie, The Lunchbox, which won several accolades for the commendable performances of Irrfan Khan, Nimrat Kaur and Nawazuddin Siddique, quite a few tricks had been adopted to make the dishes in the movie look delectable. Barring the moments when the actors actually had to eat food, the dishes were not exactly edible. The vegetables were partially cooked to retain the colour and make them look fresh. Also artificial colors were added to the dishes to make them look luscious. 
Chris Oliver, the famed food stylist for various successful films like Pirates of the Carribean, The Rock, How Stella Got Her Groove Back, Little Fockers among others has an interesting revelation to make. There are instances when actors are required to eat a particular dish for a scene. Actors who are vegetarian cannot eat a steak. Hence, some fruit or vegetable is designed to look like a steak and accurate camera angles are maintained for a perfect view. Also, molecular gastronomy plays a major role in recreating food for the camera. 
So, now that you armed with insider information about food in movies, would you still go "Yummm" when you see a delicious dish on-screen? Nom nom! Just saying.