A method for treating morbid obesity in a body of a mammal having a gastrointestinal tract extending through a stomach and a pyloric sphincter and a wall forming the stomach and pyloric sphincter. Nutritional supplements such as vitamins and minerals may be added in small amounts, such as vitamins A, B, C, D and K, or minerals such as calcium, potassium or zinc. The exchanger heat energy output is put to use in a conventional gas-to-water heat exchanger to produce commercial quality steam. In the second stage, the pretreated biomass is extracted with a solvent such as ethanol with or without acid catalysts in order to remove lignin and release a purified cellulose stream. Also disclosed are methods for selecting compounds for use in such compositions and methods. In a particular embodiment, the chromophore is based on a distyrylbenzene core, with donor or acceptor groups attached to the central benzene ring.