Our goals are twofold. First to have a child who eats a sufficient range of food that they won't get nutritional deficiencies and second to have a child who can cope in society, that is, they can eat with friends and other families without causing a scene or difficulty.
What hasn't worked:
This may be controversial but treating this as a discipline issue hasn't worked. Bringing out the food again or not allowing dessert has been counter-productive. Trying this tactic on fussy eaters leads to nothing being eaten.
Producing stressful situations-when we've made a big thing of likes/dislikes nothing gets eaten.
So what has worked?
Time-most children eat a wider range with age. For us this has meant that a very narrow range has broadened, not to everything, but to a much easier and more acceptable range.
Trying different foods-not all will be liked but there will be surprise likes.
Soup-we use soup as a means of increasing vegetable intake and also trying different vegetables. The soup is pureed so issues of new textures are removed leaving the new taste. If the soup is eaten, it is worth trying the actual vegetable. Many vegetables seem to be eaten as soup which might otherwise be avoided.
Practicing for social situations. Negotiating meals with friends and family is difficult for children with food issues. We practice using an unlikely example. "What will you do if Mrs X offers you shark's eye soup or ham sandwiches?"
The appropriate answer
"I would prefer a ham sandwich."
What to do if there is no alternative
"Please may I have a very small portion."
How to be polite when you hate shark's eye soup
"Thank you for making the soup."
This doesn't get over the problem of what to do if shark's eye soup makes them gag but does put them in a more confident position to manage. We have seen covert swapping of bowls with other family members in this type of situation.
Low stress around different/possibly disliked foods. We have found that saying "I won't give you any x because you don't like it" sometimes leads to a child asking for a portion.
Providing food that will be eaten-OK not really an answer but it is better to provide the one or two vegetables that are eaten each day than for the child not to have any.
Do you have a fussy eater? How do you manage?