Women's rights groups said "We will not accept someone telling a woman, 'Sorry, you're fat, go home.'"

With over a million Instagram followers and a bestselling book, Joe Wicks is back for round two with "Lean in 15: The Shape Plan," released this month.

When Tim Davis of Beaver, Pa., tipped the scales at 318 pounds two years ago, he bought a Fitbit gadget to track his physical activity and the Lose It! app on his phone to track calories.