Denise Austin says fitness is key even with weight-loss shots Fitness guru Denise Austin explains how muscle-building, daily movement, and smart routines can yield results. NEW You can now listen to Fox News articles! 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