 Gary TaubesSelf - Investigative Science Journalist / Author | Self - Investigative Science Journalist / Author |
| NNina TeicholzSelf - Investigative Science Journalist / Author | Self - Investigative Science Journalist / Author |
| AAncel KeysSelf (Archival footage) - Physiologist | Self (Archival footage) - Physiologist |
| TTim NoakesSelf - Scientist / Author / Professor Emerita | Self - Scientist / Author / Professor Emerita |
 Mark HymanSelf - Narrator / Nutritionist / Functional Medicine Physician | Self - Narrator / Nutritionist / Functional Medicine Physician |
 Bret ScherSelf - Cardiologist | Self - Cardiologist |
| SSarah HallbergSelf - Obesity Specialist | Self - Obesity Specialist |
| ZZoe HarcombeSelf - Obesity Researcher | Self - Obesity Researcher |
| SSalim YusufSelf - Cardiologist | Self - Cardiologist |
 Robert LustigSelf - Pediatric Endocrinologist | Self - Pediatric Endocrinologist |
| JJason FungSelf - Diabetes Specialist | Self - Diabetes Specialist |
 Bill MaherSelf - Comedian (archive footage) | Self - Comedian (archive footage) |
 Eric WestmanSelf - Obesity Specialist | Self - Obesity Specialist |
| JJonny BowdenSelf - Certified Nutritionist | Self - Certified Nutritionist |
 Dwight D. EisenhowerSelf - President (archive footage) | Self - President (archive footage) |
| AAlyssa GallagherSelf - Certified Diabetes Educator | Self - Certified Diabetes Educator |
| BBrian GaudetteSelf - US Army Pilot | Self - US Army Pilot |
| BBrian LenzkesSelf - Internal Medicine Physician | Self - Internal Medicine Physician |
| DDoug ReynoldsSelf - Founder and CEO, LowCarbUSA | Self - Founder and CEO, LowCarbUSA |
| DDave AspreySelf - Founder, Bulletproof | Self - Founder, Bulletproof |
