Desserts are typically categorized as food that contains sugar or is sweet. Typically, sugar is seen as an indulgence, and in large quantities, can create a variety of health problems. The human body needs a certain amount of sugars, but once again, too much can cause a variety of problems. In moderation, sweets can be good for our health.
Furthermore, desserts have grown to encompass a range of sweets. Desserts can be as decadent as chocolate cakes, rich custardy pies, and sumptuous ice cream. All of these desserts are made with white sugar (processed sugar), so they typically are not going to do too much for our waist line or our health.
Then, there are other types of sugars derived from fruit and yogurt made from fruit sugars. Incidentally, the word dessert was comprised only of fruits and candied nuts, but today, natural sugars (while still sugar) are processed in the body much easier, some being great roughage which allows the digestive track to function efficiently. These fruit sugars are healthy and are a part of a well-balanced diet. To answer the question, yes dessert can be healthy if the sugar is from a natural source like fruit and when eaten in moderation.