This one is not true. While caffeine can stimulate muscles in the digestive system, facilitating a bowel movement, caffeine is also dehydrating. It is best to avoid caffeinated beverages if you suffer from chronic constipation. If you cannot give up coffee altogether, opt for decaf instead. How do you know if you are dehydrated? Symptoms of dehydration include light-headedness, dizziness, nausea, headache, and fatigue. Monitor the color of your urine throughout the day to check your hydration status. Dark yellow may mean you need more fluids.