Dietspotlight says that no clinical evidence is provided by the manufacturer to support the use of Stacker 3 in weight loss. The active ingredient in Stacker 3 is chitosan. WebMD says the evidence suggests that chitosan may result in the loss of up to one pound over six months.
The manufacturer of Stacker 3 received a warning letter from the Food and Drug Administration in July of 2013. It was ruled that the company engaged in misbranding and poor manufacturing practices. Many of their products were found to have ingredients incorrectly listed. The FDA also found that the company failed to confirm the identify of ingredients and failed to use sanitary handling procedures during manufacturing.