Bezoar-forming units for forming at least one temporary bezoar in a gastrointestinal organ of an animal, including a mammal, to fill a space in the said organ, are provided for weight control. The units include biodegradable fiber-based configurations of various length and shape having a first dimension and a second dimension whereby when the bezoar-forming units are located in the given gastrointestinal organ, at least one temporary, permeable bezoar is formed.
