For the first time ever, Dr. Smith holds an all-sibling weigh-in appointment,and the moment of truth is a tough pill to swallow for some.

The family deals with the aftermath of Amy's meltdown. Back home, Chris gets skin removal surgery. Amy has a risqué photoshoot. Tammy finds doctors who can do her skin removal surgery but some test results force Tammy to confess a long-held secret.

Everyone prepares for London amid another flare up between Tammy and Amanda while Chris and Tammy visit Dr. Turner hoping to get approved for skin removal surgery.

Tammy needs a new place to live but finds more problems than solutions and Amy makes a peace offering with some highly questionable ingredients.

Tammy and Amy beef over their big night out.

A time for cheer is met with jeer as the entire family remains divided during Christmas.

Chris gears up for his upcoming appointment with a plastic surgeon and encourages Tammy to tag along.

Tammy has her heart set on skin removal but is met with a roadblock.

Amy sees a paediatric dietitian and faces some difficult truths about Gage's diet. Dr. Smith makes a house call and confronts Tammy about her partying lifestyle. While on the road with Chris, Tammy's health hits a dangerous low point.

With her weight spiraling, Tammy makes a life-altering decision.

Tammy announces her engagement to the family and reveals that her big day is only two weeks away; Amy takes up maid of honor duties; the family wonders if there's another reason Tammy is rushing down the aisle.

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Chris comes down on Amy for enabling Tammy.

The family vacation starts off terribly when Tammy refuses to enter the cabin. Chris hopes he's lost enough weight to fulfill a life-long dream. A last attempt to save the vacation ends in another confrontation. The siblings discover Tammy's secret.

After a rift on the family vacation, Amy returns home and drops a bomb on Tammy. While Amy focuses on her new life, Tammy makes a decision that takes her even further away from her weight-loss goals.

Chris faces the ultimate weigh-in to get approved for bariatric surgery. With Tammy's weight at a standstill, Amy and Michael make a life-altering decision. The family's fears about Tammy's choice in partners are realized.

Tammy's seemingly good progress inspires Amy to visit, reuniting the siblings for the first time in months; Amanda begins a new chapter in her life; Amy learns she's at risk of serious complications if she doesn't get her eating under control.

Tammy wants to come home, but a setback causes a major blowup between her and the family.

Having survived yet another brush with death, Tammy recovers at rehab, but a new scare threatens her life; the family adjusts to life without Tammy; Amy's big surprise stuns everyone.

After finding out Tammy's been robbed, Misty and Amanda visit to break the news in person; while Chris pushes ahead toward his surgery goal, Amy has a setback and is rushed to the ER; with her sisters by her side, Tammy faces the results of her weigh in.

Amy must confront demons from her past, and Tammy admits to cheat days.

While Chris makes progress after his surgery, Tammy gets discouraging news. Amy plans a unique bash for Tammy's 35th birthday. The family excitedly plans their first vacation together with all five siblings, but concerns rise about Tammy's mobility.

After years of struggling, Tammy finally has her weight loss surgery, but things are not as straightforward as expected.

Tammy takes small steps towards independence, Amy moves home but struggles with ghosts of the past, the sisters get new looks to go with their new attitude, and an upcoming Dr. Smith appointment has everyone on edge.

The family arrives in London for their first international vacation and learns even more surprising news about their ancestry.