There is no scientific data to support its claims and, at the time of this writing, it is regarded as having no benefit. Bulk-producing tablets are also advertised as appetite suppressants. Bulk-producing pills contain either bran or methylcellulose. They sometimes contain some vitamins and minerals. Caffeine and PPA both tend to give a person a high.
Caffeine is a diuretic.
This means more frequent urination and weight loss from water loss. PPA can be taken in accidental overdoses if medicines are taken with it. According to the American Medical Association, risks associated with PPA include temporary dramatic elevations of blood pressure, dizziness, nausea, nervousness, and insomnia. There is no scientific data to substantiate claims that weight loss from the use of any of these diet aids is permanent. While some diet aids may not actually be dangerous, this is not the case with starch blockers.