Karen Carpenter's last months are being discussed in a new biography of the talented but troubled singer.

Carpenter, known for being half of iconic '70s duo The Carpenters along with her brother, Richard, died on Feb. 4, 1983, from heart failure related to her battle with anorexia. In the months before her death, she had been receiving "radical" treatment from psychotherapist Steven Levenkron in an attempt to overcome her eating disorder. She cut the treatment short against his recommendation after declaring that she was "cured," the book reveals.

In an excerpt from "Lead Sister: The Story of Karen Carpenter" by famed music journalist Lucy O'Brien, shared by The Hollywood Reporter, the singer's treatment is described in new detail as well as the days leading up to her death.

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A photo of Karen Carpenter

Karen Carpenter is known for singing hits like "Close to You" and "Superstar." (Harry Langdon)

In 1982, years after she began showing symptoms of anorexia – a disease that was mostly a mystery at the time – she moved from California to New York in hopes of finding relief.

"Anorexia had become a tyrannical force in Karen’s psyche, telling her that food was an enemy to be fought," O'Brien wrote. "Thoughts of food and the methods to eliminate it had become obsessive, dominating her day and disrupting her sleep."

Under Levenkron's care, "Karen would be dependent on him in order to override the authority of the disease, until she established her own separate identity. He would become a father figure, guiding and navigating her through the process," O'Brien explained.

The Carpenters

The Carpenters pose for a portrait in 1977 in Los Angeles. (Harry Langdon/Getty Images)

His methods were considered "controversial" and "radical," but Carpenter "knew instinctively that she needed someone strong to help her fight the anorexia, someone who saw through her denial and her attempts to hide the illness."

She lived in the City Regency Hotel during her time in New York, and friend Karen "Itchie" Ichiuji moved in as well. Despite her intent to overcome her disease, O'Brien wrote that "from the beginning she was undermining the treatment in surreptitious ways. Levenkron's office on East 79th Street was 19 blocks away from the Regency Hotel, but instead of conserving energy by taking a limousine, Karen would power-walk up Madison Avenue, burning calories as she did so. After breakfast with Itchie — bacon, two eggs over easy and toast — she would visit the bathroom and ingest Dulcolax laxatives so she could purge. And in the suite she found it hard to relax, standing and continually moving about in order to lose weight."

A photo of Karen Carpenter

Karen and Richard, a brother-sister duo, made up The Carpenters. (Getty Images)

Carpenter reportedly told Levenkron that she could take over 90 laxatives at once, and she did so to expel any food she'd digested. O'Brien also wrote that the singer took 10 thyroid pills daily to increase her metabolism.

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Upon hearing that, "Levenkron was horrified. Overdosage of thyroid medication could lead to coma, convulsions and heart attacks." He confiscated the medication and made a plan for her to cut back on the laxatives with the eventual goal of stopping them altogether.

Months passed, the excerpt continues, and during one therapy session, he told her that she needed to let him care for her so that the treatment could work. She refused, saying that she was "successful" how she was, but he allegedly responded, "But you do need care because you are incompetent … because you can’t keep yourself alive."

Fox News Digital has reached out to Levenkron for comment.

Karen Carpenter

Karen Carpenter moved to New York for a "radical" treatment for anorexia. (Ron Howard/Redferns)

Summer came, and Carpenter's friend, Ichiuji, called Levenkron to complain about her apparent lack of progress or weight gain, and he made the choice to try something more "confrontational."

"The next day he got Karen to change into a bikini, stand in front of a long mirror and look at her emaciated body," O'Brien described. "She didn’t see anything wrong; in fact she told him she was gaining some weight."

In September, Carpenter informed the psychotherapist that her heart was "beating funny" and that she'd been feeling dizzy. He had her admitted to a hospital, and upon checking in she weighed 77 pounds and had a life-threateningly low blood potassium level of 1.8 – the book notes that levels between 3.6 and 5.2 are considered normal. She was fed through an intravenous drip.

Carpenters music

The Carpenters perform at in Tokyo on May 31, 1974. (Koh Hasebe/Shinko Music/Getty Images)

"Over the next seven weeks she gained 20 pounds," O'Brien wrote, and on Nov. 8, Carpenter checked herself out of the hospital. Two weeks later, she said she was "cured" and made plans to return home to Los Angeles.

"Levenkron told Karen she was leaving him too soon, that treatment would take at least three years, but she waved away his concern, promising to follow up with him on the phone."

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In the next couple of months, Carpenter kept busy, getting back to her old life. She spoke of recording new music and performing, and O'Brien noted that "Those around her felt relief and delight at what seemed to be progress."

A photo of Karen Carpenter

Karen Carpenter was also known for her talent for playing the drums. (Hulton Archive)

But on Jan. 27, 1983, Carpenter collapsed at her apartment, O'Brien wrote. Her housekeeper found her and got her into bed, and when she checked on her later, the singer told her she was feeling better.

On Feb. 3, she went shopping with her mother for a new washer-drier. When she couldn't find one, she slept over at her parents', Agnes and Harold, house so they could go out again the next morning.

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"On the morning of Feb. 4," the book reads, "Karen awoke, padded down to the kitchen, turned on the coffee pot and went back upstairs. At 8:45 a.m. Agnes heard the wardrobe doors slide open in the room above. ‘Karen’s up,’ she said to Harold, before going down to the kitchen."

A photo of Karen Carpenter

Karen Carpenter died of heart failure related to her years-long battle with anorexia. (Sherry Rayn Barnett/Michael Ochs Archives)

"When the coffee was ready she called the bedroom phone, but Karen didn’t answer. Agnes went to the foot of the stairs and called again but there was no response, so she went up to the bedroom. She found Karen lying unclothed and motionless on the wardrobe floor. Clutching her close, she screamed to Harold to call for help."

Carpenter was admitted to the local hospital at 9:23 a.m., and at 9:51 she was pronounced dead.

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O'Brien wrote, "Agnes and Harold were distraught. ‘Can’t you bring her back?’ they wailed, but Edwards [her doctor] gently explained there was nothing more they could do. Richard, meanwhile, sat there feeling numb and hopeless, trying to process the fact that his sister, his lifelong musical partner, was dead at 32 years old."