Moringa is very potent. The average person can take 2-3 teaspoons on an empty stomach with water to use it as a fast acting and natural laxative. Remember people differ so will the impact of how much you take.
Many use Moringa and an increased water intake to keep them regular - this does not require taking it on an empty stomach. If you get a runny tummy from Moringa, just reduce your dosage, or take it when your stomach has food in it.