The Exchange System provides a quick way to estimate energy, carbohydrates, protein and fat content in any food or meal. Free foods contain fewer than 20 calories per serving and less than 6 grams of carbohydrate per serving. The key word is moderation. These foods are not totally calorie free.
Free foods have a high water content.
When they are cooked they loose the water and become more concentrated. Therefore, cooked free vegetables have smaller portion sizes. Water loss occurs as heat breaks down the membranes of the cells that compose the food product. I think you skipped over the part of my question that mentioned that for some meals in the month of meals five, some exchanges might have been substituted for others. It's right in the beginning of the book.