Television reality show “The Biggest Loser” returns tonight with its fourth season: NBC promises the same premise, a new host and new twists.

This time around, the brave contestants fighting to shed those extra pounds will benefit from the smiles and encouraging words of Alison Sweeney, of “Days of Our Lives” fame. The actress replaces comedienne Caroline Rhea as host of the reality series.

As usual, a group of very overweight contestants will have to strive to lose those pounds from one day to another and the next, with the help of professional trainers giving them tips, monitoring them and pushing them further and further.

This season also brings an extra trainer, as Jillian Michaels returns after a year of absence and joins Bob Harper and Kim Lyons.

“The Biggest Loser” first aired in October 2004 and enjoyed good ratings, as Americans tuned in to watch the participants become healthier and fitter. In the end, the contestant to lose the most weight and percentage of body fat wins $250,000.

NBC revealed in August who this season’s contestants would be. The youngest among the 18 hopefuls is a 21-year-old girl from Franklin, TN, while the oldest is a 62-year-old man from Peoria, IL. NBC says he is the show’s oldest contestant ever. The remaining 16 participants have ages between 24 and 40.

One is a Hurricane Katrina survivor from Louisiana; another is a paramedic from Texas. There is also a set of twins.

NBC announced the contestants would be taken from the traditional ranch and there would also be an additional Black Team, trained by Michaels, comprised of contestants that had failed to be chosen for the Red Team, trained by Lyons, or the Blue Team, trained by Harper.

Previous contestants on “The Bigger Loser” have reported impressive success stories, such as last season’s winner, Erik, dropping an amazing 214 pounds.

Photo credit: NBC.com