75 Hard fitness challenge draws expert warnings as toned-down versions gain traction

An extreme, all-or-nothing fitness regimen is going viral again as millions seek rapid weight loss and mental toughness through its relentless daily rules. But as health experts warn the intensity may be unrealistic for many people, lighter versions of the challenge are also picking up steam.

Fueled by social media buzz and dramatic celebrity transformations, the viral 75 Hard challenge, created in 2019 by entrepreneur and podcaster Andy Frisella, requires participants to follow a rigid...