American writer Lionel Shriver has never shied away from provocative topics. Her chilling bestseller We Need to Talk About Kevin revolved around an ambivalent mother whose troubled son carries out a mass shooting.

Now, with her new book Big Brother, coming out in Canada on June 4, she explores the emotionally fraught subject of obesity.

Shriver’s own brother became severely obese and died of health complications from his obesity in 2009. That experience fuelled her interest in fat and how our culture perceives it, she told CBC’s Q cultural affairs show.

"It’s not about my brother. It’s about a completely fictional family. The plot never happened in real life, but it was certainly inspired by the fact that I saw the consequences of obesity up close," Shriver said from London, where she lives and works.

"I came to some appreciation for how complicated it is, how easy it is to just give up and let go, and how much our eating disorders…are entwined with a lot of emotional issues and relationships with our family and friends."

Protagonist and sibling struggle with weight

Big Brother's main character Pandora tries very hard to understand why her brother, Edison, has gained an astonishing amount of weight and what drives him to eat so much. She struggles with her own weight also, at one point losing more than 20 kg. However, she finds being thinner does not solve her problems.

Shriver says reaching for food seems to be an attempt to fulfill a need in contemporary life, though most people can’t figure out what they really want. She believes many Americans feel depressed and are trapped in joyless, low-wage jobs that go nowhere.

"I am concerned that obesity is a sign of a broader unhappiness, a broader lack of satisfaction in America," she said, adding that there is a moral stigma attached to being overweight.

"We have loaded a huge moral significance onto what people weigh and I think it is overdone. It’s one thing to say, yes, obesity is a health problem. But we are stigmatizing people who are overweight to such a degree that I think, in a way, we regard them as evil."

In fact, her novel zeroes in on a culture obsessed with body image and exposes those who talk continually about diets and exercise fanatics.

"I’m upset by how much time people spend anguishing about food — either planning what to eat or regretting what they did eat. It’s a waste of energy," Shriver said.

In Britain, where the book was released earlier this month, the press was obsessed with Shriver's own eating and exercise regime — she eats only once a day. However, that line of questioning overlooks the point of Big Brother, she said, which is to look behind what we call the "obesity epidemic" and try to discover its cause.