Chocolate is a common cause of constipation, according to MedicineNet. In a survey conducted by German researchers, patients were asked to name foods they thought were responsible for their constipation, and chocolate was mentioned the most frequently.
Although doctors aren't sure why chocolate causes constipation, they believe the high fat content in chocolate can interfere with the digestion process by causing bowel muscles to contract more slowly, thus preventing digested food from moving normally though the digestive tract. Other foods that may cause constipation include dairy products and red meat when consumed in large quantities, states MedicineNet. Consuming caffeinated drinks, especially when dehydrated, and eating unripe bananas can also lead to constipation.