My 3 year old will not eat

My son just turned 3 and we have an ongoing problem with his food intake. I'm writing today and I am desperate since he has not been eating for about 3 days. He'll take a bite here and there but I do mean a bite. He has never beer a really good eater but not I'm getting really concern since I can see him loosing weight. I've been asking his pediatrician and all I'm getting is that children go though these stages and he'll eat when he is hungry but it's been 3 days and I do not see any changes.
I read about giving kids ice cream and Pediasure. He will probably eat ice cream but does not like any flavored milk or shake drinks. By giving him ice cream I feel guilty because of the sugar he gets and I can skip any other kind of food, he won't even look at it after having ice cream.
My son underwent open heart surgery when he was 5 days old (TGA) but he's been doing very well heartwise so It's not heart related but It does concern me that because of that he might need more calories then other kids his age. I worry that he just doesn't get enough nutrition for proper development. What else can I do for him?????

[Renee Radenberg]

His weight is just above the 25th percentile which indicates he is normal for his age and not underweight unless his weight has been decreasing. It is frustrating when children not interested in food. At this age some children are too busy to eat and become 'picky eaters'. Engage him with preparation of food. Have him help you set the table or do something for the meal. Children love to be a part of making food. Hopefully it will increase his interest in food. Ice cream may have sugar; however, it is packed with protein, calcium, vitamin D, and calories for a child to gain weight. Mealtimes can be a battlefield when children do not have an interest to eating or eat very little. It becomes the battle of the wits between the child and the parents. The most important thing is to RELAX. Remember meals need to be joyous for parents and the child. If he will not eat a certain food, do not make a fuss over it. Give him some other food alternatives. Then let it go and enjoy the meal. Let him eat what he wants. Slowly introduce new foods, and if he does not want it, do not make a fuss over it. Try again in a few weeks. Hoped this helped you.