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Entirely different mechanisms

Switching brands while maintaining the same peptide may resolve irritation
Deficiency of liver adipose triglyceride lipase in mice causes progressive hepatic steatosis

where Madonna, Katy Perry and Justin Timberlake have also admitted regularly having the vitamin boost and where injections are said to aid weightloss because they increase energy levels and boost the metabolism
doi: 10.1507/endocrj.k09e-117