Green coffee bean extract, one of the active ingredients in Plexus Slim, reduces sugar absorption from the digestive tract and it also stimulates the metabolism to increase the number of calories burned each day. Another active ingredient in Plexus Slim, garcinia cambogia extract, is thought to reduce appetite and prevent deposition of body fat, says WebMD.
The third active ingredient in Plexus Slim, alpha lipoic acid, is believed to lower blood sugar levels, says the University of Maryland's Medical Center. However, the evidence supporting the use of these ingredients for weight loss is modest at best, says the Mayo Clinic. Green coffee bean extract may have a modest effect on weight loss, but it also has many side effects, including anxiety, agitation and an irregular heartbeat.
Garcinia cambogia is "possibly ineffective" for weight loss, and its use can cause nausea, stomach upset and headaches, says WebMD. The safety of long-term regular use of garcinia camobogia is unknown. The University of Maryland's Medical Center states that most studies of alpha lipoic acid have used intravenous infusions, not oral intake of the compound. Studies of oral intake of the compound are poorly designed and include very few subjects.
According to the manufacturer, the active ingredients in Plexus Slim are green coffee bean extract, garcinia cambogia fruit extract and alpha lipoic acid. The product is intended to be consumed about half an hour before each meal.