Sorry, you’ve caught me with my mouth open. Agape actually. Catching flies, dust, sweet wrappers. Anything that’s passing. Those ridiculous titles for documentaries that Channel 4 is so keen on are jolting, if not outright offensive. But Half Ton Mum was the sad, and sensitively told, story of how Renee Williams – at 64st, the world’s heaviest woman – died after the gastric surgery that she hoped would change her life.

Renee was beyond huge; fat rolled, puffed and draped. But she was also funny, determined and had two lovely daughters, one of whom, Mirina, was eloquent and headstrong. Apparently she has become a source of inspiration to other obese people seeking treatment. The footage of walls getting cut down and emergency services descending to release the “super-morbidly obese” from nothing less than captivity led to the first of my stricken expressions.

My face remained frozen for the duration of My Fake Baby, which identified a new industry in dolls made to look and behave like living babies. The people who buy them push them around in prams and wash their hair. The dolls are customised to customers’ specifications: a cut on the knee, a red mark above the eyes, clenched hands. They can even be fitted with a breathing mechanism.

The dolls, or “reborns”, are made by Jaime Eaton, a sunny young mother of four who said that after four Caesareans, this would be the “closest” she would get to having more children. “I’ve cried when I’ve let a few of them go,” she admitted. We watched her put a baking tray of rubber baby parts in the oven. You could have anything you liked, she said, a wriggling baby, one with raised capillaries, birthmarks. Her own children bashed each other with sundry infant body parts and seemed unperturbed at sharing their home with these grotesques.

One lady, Sue, had quite a few reborns in a spookily beautifully kitted-out nursery. She couldn’t do with the noise of the real thing: “I want them well behaved and clean and the reality isn’t like that,” she said. She took her “children” for walks and even had a bottleholder for their formula (fabric conditioner, not milk). She spent nearly £300 on clothes for a new baby, Sophie, who she travelled to America to pick up. (I know, mouth still open.) But Sophie had a crack in her head – she wasn’t perfect. Sue sent her back. (Mouth still open, eyes now swivelling.)

Christine was contemplating coping with the loss of a child called Harry with a doll replicant. Jaime said she never asked why people bought the dolls; if they paid the money, she was just providing a service – admirably hard-nosed though not immediately apparent to the customers, who like Christine, unburdened themselves to her as to why they were thinking of investing in one of the freaky things. Harry hadn’t died. His mother, Christine’s daughter, had cancer and Christine looked after Harry. Her daughter’s cancer went into remission and she and Harry moved to New Zealand, leaving a huge Harry-shaped hole in Christine’s life.

She went online and found a woman who lived near by and had a roomful of reborns. Deeply sinister they all looked too, but the women cooed over these inanimate objects as if they were real, breathing, darling little things. When Christine went to pick up her Harry doll from Jaime, she cried ecstatically: “Nobody will be able to take him away from me this time.” Goodness, you felt for her husband, Arn, a voice of common sense and reason, who on seeing the Harry doll noted: “I don’t like it Christine. It makes me think of something on a mortuary slab.”

He was right, and his words punctured the madness that the producer and director Victoria Silver brilliantly captured. She never mocked her subjects (one forgiveable lapse was the spooky music, but she could have really gone to town given her source material). Christine and Sue were resolute that what they were doing was normal. One said that she felt like “someone, not invisible” when with a baby.

When Christine held the doll up to the real Harry, now a small boy, in New Zealand, he exclaimed: “It’s just a doll!”

“No, it’s a baby,” said Christine. “It’s a doll,” insisted Harry, I think after calling his grandmother what sounded like “numbnut”. You felt quite relieved he was in New Zealand.

Out of the box

— After the black hole of nonhilarity that was MTV’s Totally Jodie Marsh: Who’ll Take Her Up The Aisle? comes an attempt to marry off a notable bachelor. ITV2 is rumoured to be doing a reality show with Calum Best as he searches for a long-term partner. “He has had enough of s****ing around . . .” one source told a Sunday tabloid.

— For years he helped lucky members of the public on the way to a Blankety Blankchequebook and pen – and now, according to tabloid reports, Terry Wogan is about to return to the land of the quiz show. ITV has apparently approached him to host a 5pm quiz to run opposite Paul O’Grady on Channel 4. It’s thought his usual gigs (not least his Radio 2 show) would remain unaffected.

Editor's choice

• The 100 Best Films of the Decade
• 70 facts you didn't know about Marvel
• The 50 Biggest Movies Of 2010