Dried plums are rich in insoluble fiber, a key nutrient to help fight constipation. “Insoluble fiber doesn’t dissolve in water and creates more bulk so waste can push through the digestive system,” says Wayne Andersen, MD, medical director of Take Shape for Life, a weight loss program from Medifast. Prunes also contain two substances that act as natural laxatives, sorbitol and dihydrophenylisatin, which will work much better for your system over time than drugstore constipation aids. “The body can become desensitized over time to over-the-counter laxatives,” Dr. Andersen says. Start with just one prune a day first and bump up your intake to two if you don’t see a response.