One of the most common PMS complaints is fluid retention. This particular problem is generally provoked by excess sugar.
Sugar triggers the pancreas to secrete insulin.
Insulin is a reaction to excessive rise in blood sugar. Insulin secretion can lead to the formation of ketoacids. Please keep in mind that the body really doesn't know the difference between a refined sugar and a slower acting starch carbohydrate. Sugar is sugar especially when it is broken down to its end product. Ketoacids, the end products of fat metabolism, help the kidneys clear excess sodium and water.