Jim Abrahams
— Self - Father / Founder, Charlie Foundation / Filmmaker
Vinnie Tortorich
— Self - Narrator / Producer / Trainer / Author
Bret Scher
— Self - Cardiologist
Gary Taubes
— Self - Journalist / Author
Dave Feldman
— Self - Software Engineer
Eric Westman
— Self - Internal Medicine Doctor
Andreas Eenfeldt
— Self - Physician
Drew Pinsky
— Self - Physician
Georgia Ede
— Self - Psychiatrist
Nina Teicholz
— Self - Journalist
Vilhjalmur Stefansson
— Self - Explorer (archive footage)
Ivor Cummins
— Self - Biochemical Engineer
Ancel Keys
— Self (archive footage)
Jeffry Gerber
— Self - Physician
George McGovern
— Self - Politician (archive footage)
Gary Fetke
— Self - Orthopaedic Surgeon