Fussy eaters (and yes, there are many!) are simply trying to express their independence with a say in what, when, where and how they eat. Here are some ideas if your child's fussy eating is driving you to distraction.

Children’s appetites are affected by growth cycles, and they have different taste preferences (or palates) to adults. Even babies have fluctuating appetites. You will encourage your baby's appetite to work properly if you give her more when she’s hungry and let her eat less when she’s not interested. Many children are fussy eaters.
Growth slows down and appetites become erratic between one and five years. Sometimes your child will refuse food just because it provokes an interesting reaction – from you! Just try again another day. If you keep offering a particular food, your child is more likely to try it and eventually like it.
While you provide the food, your child is in charge when it comes to what and how much she eats. Toddlers have a strong need for rituals and for what's familiar. If your child asks for the pasta without the sauce, this might just be a way of getting simple, easily identifiable foods that boost her sense of security. It might also be a sign that your toddler is seeking greater independence. There's nothing wrong with supporting this move for independence by granting simple wishes such as removal of crusts from bread. The key is to let your toddler make choices while still providing a healthy, varied range of foods.
If your toddler is too distracted to sit at the family table for a meal, you can try having quiet time first to allow her to calm down before eating. Even the ritual of hand-washing can help achieve this. In general, if your kids see you enjoying food, it will encourage them to do likewise. You might encourage your toddler to sit at the table with the family for most meals, but only for 15 minutes or so until she is older and able to sit still for longer.
Your child's appetite varies. She won't starve if she is eating hardly anything. But if this really worries you, the following tips can kick-start some changes:
National Health and Medical Research Council (2003). Dietary guidelines for children and adolescents in Australia. Canberra: Australian Government Publishing Service.
Thompson, S.M. (1999). Fussy eaters: Advising parents of toddlers. Modern Medicine of Australia, March, 18-22.