According to a study in Spain, the tannins and saponins in papaya leaf tea inhibit our pancreatic lipases. Lipases are fat-digesting enzymes. Inhibiting lipases can contribute to weight loss, as discussed in the research below.
Natural inhibitors of Pancreatic Lipase as new players in obesity treatment
Authors: de la Garza AL, Milagro FI, Boque N, Campion J, Martinez JA
Ana Laura de la Garza, Fermín I.Milagro, Noemí Boque, Javier Campión, J.Alfredo Martínez
Department of Nutrition and Food Science, Physiology and Toxicology, University of Navarra, Pamplona, Spain
A number of studies have revealed various health benefits of plant polyphenols and their importance in foods, beverages and natural medicine. In this context, polyphenols have some potential efficacy for preventing obesity. They inhibit enzymes related to fat metabolism including PL, lipoprotein lipase, and glycerophosphate dehydrogenase . Polyphenol extracts are able to decrease the blood levels of glucose, triglycerides and LDL cholesterol, increase energy expenditure and fat oxidation, and reduce body weight and adiposity [75,76]. In fact, many polyphenols, including flavones, flavonols, tannins and chalcones, have shown an inhibitory activity of PL [9,22].
Flavonoids are a type of plant secondary metabolites which are characterized as containing two or more aromatic rings, each bearing at least one aromatic hydroxyl and connected with a carbon bridge . Some of them are polymerized into large molecules, either by the plants themselves or as a result of food processing. These polymers are called tannins and three subclasses (condensed tannins, derived tannins and hydrolysable tannins) exhibit a variety of beneficial effects on health .
Saponins are a major family of secondary metabolites that occur in a wide range of plants species . These compounds have been isolated from different parts of the plants, including the roots, rhizomes, stems, bark, leaves, seeds and fruits. Occasionally, the whole plant has been used .
Saponins are categorized into two major classes, the triterpenoid and the steroid saponins, which are both derived from the 30 carbon atoms-containing precursor oxidosqualene [107,108]. Some of the triterpene-rich plant materials are common foodstuffs consumed in large amounts in Mediterranean countries. Therefore, the correlation of a triterpene-rich diet and the beneficial effects of consuming a Mediterranean diet should be investigated in more detail .
These types of plant secondary metabolites are found to inhibit PL and, thus, may represent potential effective treatments for obesity and related disorders [9,22]. One example are different saponins isolated from tea  or ginseng .
Papaya Leaf Tea is rich in tannins and saponins. Detailed analysis of this is in the research below: