While she carried Hunter's words with her, by 2012 she had reached a size 18 to 20.
After divorcing her first husband, Michael, Mone says she also battled with depression.
She said: "I was at my heaviest and had three children running around me and [I was] launching Ultimo around the world. I was getting bigger and bigger. I was abusing myself. I was on antidepressants from the doctor. It was awful."
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Mone has also shared that her parents tried to intervene and her father wrote her a letter imploring her to help herself.
"My mum and dad used to be in tears. My dad wrote me heartfelt letters saying, 'Please Michelle, just do it for yourself, I'm begging.'"
And Mone says her mother physically shook her and said: "Enough of this nonsense and feeling sorry for yourself, you'll have more to feel sorry for if you can't put food on the table for your kids so ... make it work."
In the years that followed, Mone dramatically changed her habits and got her health back on track. Now she's keeping her physique by working out in her gym and taking 90-minute walks every day with her fiance, billionaire Doug Barrowman.
She told the Daily Mail she and her husband-to-be also meditate for 15 minutes before bed every night. She added that she is "one trillion per cent" the most confident she has ever felt in her life.
Baroness Mone, dubbed Baroness Bra because of her Ultimo underwear empire founded in 1999, says she only pulled through thanks to the support of her parents who told her to "stop feeling sorry for yourself".
Mone had been due to marry Barrowman in London at the weekend in the Chapel of St Mary Undercroft in Parliament. Instead the couple is in lockdown on the Isle of Man.
They still celebrated the day, however, on a Zoom call with family and friends ahead of the rescheduled date this August.