"My 600-Lb Life" season 5 may be the most gut-wrenching yet. TLC follows morbidly obese twins Brandi and Kandi who weigh nearly 1,200 pounds between them. The season teaser shows 575-lb Brandi screaming as her 604-lb sister Kandi nearly dies from obesity-related cardiac arrest and brain damage. Can the show's bariatric surgeon Dr, Younan Nowzaradan save these women with gastric bypass surgery before one-ton weight kills them? And updates from two familiar faces with massive weight loss, who've found their true beauty, give hope.

TLC shows obesity is silent murderer

On "My 600-lb Life", twins Brandi and Kandi weigh almost 1,200 pounds between them. Both are nearly incapacitated by obesity and totally reliant on each other. They sleep in the same bed and help each other. Brandi is terrified when Kandi suffers a near-fatal health emergency in which obesity stops her heart. When doctors say the young woman may have suffered brain damage, both sisters get a wake-up call to lose weight. But can they shed enough weight so Dr. Now can perform gastric bypass surgery? Can bariatric surgery and changed eating habits save them in time?

Chay Guillory finds peace as Lola

Remember "My 600-lb Life" "Chay's Story" about a spunky transgender Chay Guillory from Louisiana?

Well that young man is one of Dr. Now's biggest success stories. Chay wanted to lose enough weight not only for gastric bypass and skin removal surgery but also gender reassignment surgery. Dr. Now didn't think Chay's body could handle that many procedures. And Chay wasn't keeping up with weight loss after coming out as Lola.

She faced some rejection and struggled with blame and self-pity. But happily, Lola decided to put on her big girl pants, literally. Season 5 shows the obviously smaller LGBT gal shopping for women's clothing, rejoicing to find dresses that fit, and getting a lot of positive energy from smiling clerks.

What's up with Teretha Hollis-Neely?

That's what you're going to find out this season. Teretha Hollis-Neely teased on Facebook, an update on her weight loss. She's been posting photos from a recent surgery, but can't tell folks how much she's lost (show rules, apparently). Did she lose enough for the coveted skin removal surgery? If you want to know what's up, check out Discovery for "Teretha's Story" update. And don't miss season 5 of "My 600-lb Life" which airs Jan. 4.